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Hydraulic model of Alberni harbour Nuttall, John Blakely 1951

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HYDRAULIC MODEL OP ALBERNI HARBOUR by JOHN BLAKLEY NUTTALL ; . «_ . J oU &U,fct,U^ A THESIS SUBMITTED IN PARTIAL FULLFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE i n the Department of MECHANICAL ENGINEERING We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o the s t a n d a r d r e q u i r e d from c a n d i d a t e s f o r the degree o f MASTER OF APPLIED SCIENCE. Members o f the Department o f MECHANICAL ENGINEERING THE UNIVERSITY OF BRITISH COLUMBIA Vancouver Canada O c t o b e r , 1951 i ABSTRACT A h y d r a u l i c model of A l b e r n i Harbour was b u i l t t o s t u d y the m i x i n g of f r e s h and s a l t w a t e r , t h e d i s p o s a l of i n d u s t r i a l sewage, and the r e s u l t o f proposed p h y s i c a l changes i n the Harbour. The model was b u i l t t o a s c a l e o f 1/1000 h o r i z o n t a l l y , and l / 8 4 v e r t i c a l l y . A m o d i f i e d form of L o r d K e l v i n ' s t i d e p r e d i c t i n g machine i s used t o compute the t i d e s and thus c o n t r o l a p a i r of v a l v e s w h i c h add s a l t w a t e r and remove mixed w a t e r . R i v e r d i s c h a r g e i s m a n u a l l y a d j u s t e d . A method o f removing w a t e r samples from the o p e r a t i n g model f o r c h e m i c a l a n a l y s i s was d e v e l o p e d as a means of o b s e r v i n g s a l i n i t y d i s t r i b u t i o n . A t p r e s e n t the model i s r e a d y f o r v e r i f i c a t i o n and e x p e r i m e n t . TABLE OF CONTENTS Page I . INTRODUCTION . 1 I I . MODEL LAWS' 3 I I I . CONSTRUCTION 10 1. Model Bed 10 2. T i d e Computer 11 3. C o n t r o l V a l v e s 15 4. C o n t r o l F l o a t and Servo-mechanism. . 16 5. T i d e R e c o r d e r 17 6. R i v e r Headwords 17 IV. INSTRUMENTATION 18 1. Methods o f O b s e r v a t i o n 18 2. V e r i f i c a t i o n . . . 19 V. DISCUSSION 20 V I . LIST OF WORKS CONSULTED 27 LIST OP ILLUSTRATIONS F i g u r e A f t e r Page -F r o n t e s p i e c e : L o c a t i o n Map of A l b e r n i I n l e t I 1. A l b e r n i Harbour i v 2. V a r i a t i o n o f R e s i s t a n c e C o e f f i c i e n t with, the Reynolds Number f o r P i p e s 5 3. C o n s t r u c t i o n of the Model B a s i n 10 4. Harmonic C o n s t a n t s f o r P o r t A l b e r n i 12 5. Method of Summing T i d a l Components 13 6. T i d e Computer 14 7. C o n t r o l V a l v e d e s i g n 15 8. ' C h a r a c t e r i s t i c s of C o n t r o l V a l v e s 15 9. C o n t r o l V a l v e L i n k a g e 16 10. Servo-Motor C o n t r o l C i r c u i t 16 11. H e i g h t of T i d e Vs. Model S u r f a c e A r e a 16 12. Water Sampler 18 13 -17 Photographs of the Model 26 I n c l . ALBERNI HARBOUR Sooo 16,000 Figure 1 1 HYDRAULIC MODEL OP ALBERNI HARBOUR BY JOHN B. NUTTALL INTRODUCTION T h i s t h e s i s d e s c r i b e s the c o n s t r u c t i o n of a h y d r a u l i c model of A l b e r n i Harbour. The model was b u i l t t o s t u d y the m i x i n g of f r e s h and s a l t w a t e r , d i s p o s a l o f p u l p m i l l sewage, and the e f f e c t s of proposed p h y s i c a l changes i n the h a r b o u r . As A l b e r n i I n l e t i s t y p i c a l of many B r i t i s h Columbia f i o r d s , t he r e s u l t s of t h i s r e s e a r c h are e x p e c t e d t o be w i d e l y a p p l i c a b l e . The o c e a n o g r a p h i c a s p e c t s o f A l b e r n i I n l e t a r e d e s c r i b e d by T u l l y ( 7 ) , who used a s m a l l model o f the ha r b o u r i n w h i c h the s c a l e s were, h o r i z o n t a l . . . . 1/4308 v e r t i c a l l / 2 8 8 . A s i m p l e harmonic t i d e was re p r o d u c e d and wind e f f e c t s 2 were s i m u l a t e d . A l t h o u g h i t gave much v a l u a b l e i n f o r m a t i o n , i t s s m a l l s c a l e d i d not a l l o w the p r e c i s i o n o r d e t a i l ex-p e c t e d w i t h the p r e s e n t model. The s c a l e s used f o r the model d e s c r i b e d i n t h i s paper a r e , h o r i z o n t a l . . . . l/lOOO v e r t i c a l l / 8 4 . The a c t u a l s i z e of the model i s t h e r e f o r e 23 f e e t l o n g by 7i f e e t wide, and c o v e r s the area shown i n F i g u r e 1. The model bed i s b u i l t of c o n c r e t e s e t i n a wooden framework. S i n c e no l i t e r a t u r e on the c o n t r o l mechanism o f d e n s i t y s t r a t i f i e d models of the s i z e of the p r e s e n t model i s a v a i l a b l e , an e s s e n t i a l l y new problem was p r e s e n t e d . T i d a l c o n t r o l r e q u i r e s an a u t o m a t i c mechanism t o compute the t i d e and a p p l y i t t o the model. A m o d i f i e d form of L o r d K e l v i n ' s t i d e p r e d i c t i n g machine i s used as the computer; i t s o u t p u t i s f e d t o two v a l v e s , one admits s a l t w a t e r , and one removes mixed w a t e r . A f l o a t mechanism compares the computed t i d e w i t h the model t i d e and o p e r a t e s a servo-mechanism w h i c h makes minor c o r r e c t i o n s i n the v a l v e s e t t i n g s . The computed t i d e and p r o t o t y p e time are r e c o r d e d on a moving t a p e ; the p r o t o t y p e date i s r e c o r d e d by a m e c h a n i c a l c o u n t e r . R i v e r d i s c h a r g e i s c o n t r o l l e d by a m a n u a l l y a d j u s t e d vee n o t c h w e i r . 3 C u r r e n t data i s t o be o b t a i n e d by o b s e r v i n g t he movement of i n j e c t e d dyes and n e u t r a l l y buoyant d r o p l e t s o f carbon t e t r a c h l o r i d e and p e t r o l e u m e t h e r . A w a t e r sampler was d e v e l o p e d i n o r d e r t o remove s m a l l samples from the model f o r s a l i n i t y a n a l y s i s . S e v e r a l of these samplers may be used s i m u l t a n e o u s l y t o produce a s y n o p t i c s u r v e y of the model, MODEL LAWS I t i s a c c e p t e d t h a t the f o l l o w i n g q u a n t i t i e s c h a r a c t e r i z e the f l o w of a homogeneous f l u i d : y i l i n e a r d i m e n s i o n s V v e l o c i t y Ap p r e s s u r e d i f f e r e n c e ^ . d e n s i t y |£ a c c e l e r a t i o n due t o g r a v i t y /JL dynamic c o e f f i c i e n t of v i s c o s i t y rr* s u r f a c e t e n s i o n € e l a s t i c modulus By Buckingham's if Theorem (3), i t may be shown t h a t a f u n c t i o n d e s c r i b i n g the f l u i d m o t i o n i s : 4 I n o r d e r t o have complete s i m i l a r i t y between model and p r o t o t y p e the seven terms i n the above f u n c t i o n must be s i m i l a r f o r b o t h . The Gauchy number, V ^ jf£ may be n e g l e c t e d i n water-ways models s i n c e the e f f e c t of c o m p r e s s i b i l i t y i s m i n u t e . S i m i l a r i l y t h e Weber number, tVcr" may be o m i t t e d p r o v i d e d s u r f a c e t e n s i o n has a n e g l i g i b l e e f f e c t i n b o t h p r o t o t y p e and model. S i n c e v e l o c i t y i n the model i s f i x e d by the c h o i c e of d i s t a n c e and time s c a l e s , t h e Reynolds number, ^^f/ju. c a n n o t , i n g e n e r a l , be made s i m i l a r f o r model and p r o t o t y p e . T h i s i s because f l u i d d e n s i t y and v i s c o s i t y cannot be a r b i t r a r i l y chosen. I n waterways models the v a l u e of ^Vf/yu. i s l e s s t h a n the p r o t o t y p e . The e f f e c t o f the d e c r e a s e d Reynolds number i s t o decrease the s c a l e of t u r b u l e n c e i n the model. Where the Reynolds number i n the model i s l e s s t h a n the l o w e r l i m i t f o r t u r b u l e n t f l o w , the model can be e x p e c t e d to bear no r e l a t i o n t o the p r o t o -t y p e , i . e. n e a r the b o u n d a r i e s . By a n a l o g y w i t h N i c k u r -adse's diagram of f r i c t i o n f a c t o r vs "E.Vjo // A t f o r p i p e s , F i g u r e 2, i t appears t h a t d e c r e a s e d Reynold's number i n the model w i l l have r e l a t i v e l y s m a l l e f f e c t i f the f l o w i s t u r b u l e n t , p r o v i d e d the model roughness can be made l a r g e enough. I t has been shown by A l l e n ( l ) t h a t i t i s sometimes d i f f i c u l t t o make the b o u n d a r i e s of a d i s t o r t e d s c a l e model s u f f i c i e n t l y rough. 5 I n the f o l l o w i n g d i s c u s s i o n and y are t a k e n as h o r i z o n t a l d i m e n s i o n s , and T£ as a v e r t i c a l d i m e n s i o n . The s u b s c r i p t s /*»v and & r e f e r t o t h e model and the p r o t o -type r e s p e c t i v e l y , and the s u b s c r i p t v- t o the r a t i o o f a q u a n t i t y i n the model t o t h a t i n the p r o t o t y p e . The l e t t e r ~t r e p r e s e n t s a time i n t e r v a l . The Froude number V can be s a t i s f i e d p r o v i d e d s u i t a b l e model s c a l e s are chosen. I n o r d e r t h a t the e q u a l i t y must be s a t i s f i e d . Now and t h e r e f o r e U n l e s s the v e r t i c a l and h o r i z o n t a l s c a l e r a t i o s are e q u a l , the E u l e r number, ^ ^/A f> , a c h a r a c t e r i s t i c of the f l o w p a t t e r n , cannot be made e q u a l i n model and p r o t o t y p e . The change i n the E u l e r number i s s m a l l however. By w r i t i n g the B e r n o u l l i e q u a t i o n f o r t u r b u l e n t f l o w (4) O.IO-0.08 0.06 R e s i s t a n c e . C o e f f i c i e n t 0 f 0.03 0 .02 0.01 \ \ ! r/k = 15 \ I •^r/k = 30, ,6 ^ r/k»6o r/k=I26 \ r7k=252 • 1 v 1 2000 ^ — r / k T 507 1000- , 10,000 100,000 1 ,000,000 • Reynolds Number VARIATION OF RESISTANCE COEFFICIENT WITH REYNOLDS NUMBER FOR PIPES r = P i p e r a d i u s k = H e i g h t o f a r t i f i c i a l r o u g h e n i n g p a r t i c l e s F i g u r e 2. where ^u.' , /v' , and >«r' r e p r e s e n t i n s t a n t a n e o u s d e p a r t -ures from the mean v e l o c i t i e s i n the X f y f a n c : d i r e c t i o n s r e s p e c t i v e l y . The mean f l o w i s t a k e n t o have the v e l o c i t y V . From the above e q u a t i o n S u b s t i t u t i n g t h i s v a l u e of & p i n ^ V y ^ j , ^ the r a t i o between model and p r o t o t y p e becomes s i n c e - . By the Froude r e l a t i o n s h i p , so the m u l t i p l i e r o f A % . 2g i n the above e q u a t i o n becomes u n i t y . The m u l t i p l i e r of the £«*ryL terms does not s i n c e 7 T h i s means t h a t k i n e m a t i c s i m i l a r i t y cannot he o b t a i n e d i n a d i s t o r t e d s c a l e model and t h e r e f o r e complete m e c h a n i c a l s i m i l a r i t y i s p r e c l u d e d . The r e q u i r e m e n t s of -*/y and ^/k are s a t i s f i e d o n l y i f the model i s g e o m e t r i c a l l y s i m i l a r t o the p r o t o t y p e . A r a t i o n a l b a s i s f o r the r e l a t i o n s h i p between v e r t i c a l and h o r i z o n t a l s c a l e s i s a v a i l a b l e i n Lacy's r u l e (1) w h i c h s t a t e s •z. The b a s i s o f t h i s r u l e i s the Regime Theory o f a l l u v i a l c h a n n e l s , of wh i c h L a c y was an e a r l y c o n t r i b u t o r . B l e n c h (2) has de v e l o p e d the Regime Theory t o i t s p r e s e n t s t a t e i n w h i c h where V i s the mean v e l o c i t y of f l o w i n the c h a n n e l , O i s the mean d e p t h , and ^ i s a c o n s t a n t depending upon t h e m a t e r i a l f o r m i n g the c h a n n e l bed and upon the s u p p l y of bed m a t e r i a l from s o u r c e s o t h e r than the bed i t s e l f . W i s c a l l e d the M b e d f a c t o r " . The s i d e f a c t o r * i s d e f i n e d as w 8 where W i s the c h a n n e l w i d t h and s» depends upon the m a t e r i a l f o r m i n g the c o h e s i v e s i d e s o f the c h a n n e l . The c h a n n e l s l o p e S i s r e l a t e d t o the o t h e r v a r i a b l e by the r e l a t i o n • _v2 , c fvw) 4 where C i s a n o n - d i m e n s i o n a l c o n s t a n t and ^ i s the k i n e m a t i c v i s c o s i t y of the f l u i d - s e d i m e n t complex. The s l o p e may be e x p r e s s e d as Q % where Q i s the r a t e of f l o w i n the c h a n n e l , i . e . Q ^ V W D I f the same m a t e r i a l forms the c h a n n e r bed and s i d e s i n b o t h the model and p r o t o t y p e , the s l o p e e q u a t i o n may be w r i t t e n f o r the model, u s i n g t h e Froude s c a l e s t o r e l a t e and ; and 5" _ - > L ? . _ ^ L > *bor the p r o t o t y p e . T a k i n g the r a t i o of 2 u * t o 9 but and t h e r e f o r e The e f f e c t o f the E a r t h ' s r o t a t i o n , C o r i o l l i s 1 f o r c e , can o n l y be s i m u l a t e d by mounting the e n t i r e model on a r o t a t i n g base. The e r r o r s due t o the o m i s s i o n of t h i s s t e p are thought t o be of the same o r d e r of magnitude as the e x p e r i m e n t a l e r r o r s i n t h i s p a r t i c u l a r model. T h e r e f o r e - f o r c e s the e f f e c t of C o r i o l l i s ^ w i l l n ot be s i m u l a t e d . The model s c a l e s were chosen as f o l l o w s : the h o r i z o n t a l s c a l e x.r - ' / i 0 o o * s e l e c t e d on the b a s i s o f l a b o r a t o r y space and w a t e r s u p p l y , the v e r t i c a l s c a l e "£.v* 1 /8>4- , s e l e c t e d w i t h r e g a r d t o Lacy's r u l e and the e f f e c t s of s u r f a c e t e n s i o n o v er the i n t e r - t i d a l a r ea of the model. H a v i n g f i x e d the h o r i z o n t a l and v e r t i c a l s c a l e s , the time s c a l e becomes from the Proude law. CONSTRUCTION The l a b o r a t o r y i n w h i c h t h i s model was c o n s t r u c t e d i s a temporary frame b u i l d i n g 20 by 40 f e e t , an o f f i c e and wash-room occupy a space of 8 by 20 f e e t . 1. MODEL BED: The model i s s e t on e i g h t c o n c r e t e p i e r s i n the l a b o r a t o r y f l o o r . Ten i n c h square beams r e s t on the p i e r s and s u p p o r t two by e i g h t i n c h l o n g e r o n s w h i c h form the model base. The s u p p o r t i n g framework was d e s i g n e d t o d e f l e c t a maximum of 0.2$ of the span between the c r o s s beams when the model i s f u l l of w a t e r . A wooden box made of two i n c h p l a n k i n g was b u i l t upon the s u p p o r t i n g framework t o c o n t a i n the;..model bed. Female plywood t e m p l a t e s cut o n e - h a l f i n c h below the r e q u i r e d model boundary were s e t i n the box. A l a y e r o f g r a v e l was p l a c e d on the f l o o r of the box and the f i r s t l a y e r of c o n c r e t e poured. T h i s l a y e r extends t o one i n c h below the top o f the t e m p l a t e s . S m a l l n a i l s were t h e n d r i v e n i n t o the plywood, the heads b e i n g p l a c e d on the r e q u l : ed b o u n d a r i e s of the model. A f i n a l l a y e r o f c o n c r e t e was t h e n t r o w e l l e d t o the s u r f a c e d e f i n e d by the n a i l heads. The method of m o l d i n g the model bed i s shown i n F i g u r e 3. A c o - o r d i n a t e system was used t o p l a c e the n a i l s . T h i s c o n s i s t e d of machined r a i l s f i x e d t o e i t h e r s i d e of the model box and a c r o s s r a i l complete w i t h v e r t i c a l N a i l s Used t o P o s i t i o n P i n a l Layer of Concrete Datum R a i l F i r s t Layer of Concrete G r a v e l Plvwood Templates CONSTRUCTION OF MODEL BASIN F i g u r e 3 11 m e a s u r i n g r o d . The a s s e m b l y i s a c c u r a t e l y made and s e t so t h a t h o r i z o n t a l measurements c a n be made t o w i t h i n l / l 6 i n c h on t h e model, o r f i v e f e e t i n t h e p r o t o t y p e ; v e r t i c a l measurements c a n be made t o w i t h i n l / 3 2 i n c h on t h e m o d e l o r t h r e e i n c h e s i n the p r o t o t y p e . T h e s e a r e e q u a l t o t h e a c c u r a c y o f t h e a v a i l a b l e c h a r t s o f t h e a r e a a n d a r e c o n s i d e r e d a d e q u a t e . P h o t o g r a p h s o f t h e model i n o p e r a t i o n a r e shown i n F i g u r e 13. I n o r d e r t o accomodate b e d movement s t u d i e s i n th e t i d e f l a t a r e a , t h i s r e g i o n was l e f t a t a s c a l e d d e p t h o f s e v e n fathoms when t h e c o n c r e t e was p o u r e d . The t i d e f l a t s were l a t e r b u i l t up w i t h s h a r p s a n d t o f i t male t e m p l a t e s . A s p r a y o f p o r t l a n d cement and w a t e r was u s e d t o " f i x " t h e a r e a f o r t h e t e s t i n g o f c o n t r o l g e a r . The c r u s t w i l l be removed and a d j u s t m e n t made b e f o r e t h e f i n a l t e s t s a r e b e g u n . T h i s a r e a i s shown i n F i g u r e 14. Water s u p p l y t o t h e l a b o r a t o r y i s as f o l l o w s : Maximum S u p p l y Maximum Head F r e s h w a t e r S a l t w a t e r 0.03 c. f . s . 0.11 c . f . s . 43 f e e t 31 f e e t 2. TIDE COMPUTER. I n p r e d i c t i n g t h e t i d e s a t P o r t A l b e r n i t h e H y d r o g r a p h i c O f f i c e u s e s 61 terms o f t h e s e r i e s (6) 12 where \r\ i s p r e d i c t e d t i d e a t any time cl , i s the a n g u l a r speed of the c o n s t i t u e n t w h i c h i s c o n s t a n t f o r any one component and depends on a s t r o n o m i c a l d a t a o n l y , , f a c t o r f o r r e d u c i n g mean a m p l i t u d e t o y e a r of p r e d i c t i o n and depends on a s t r o n o m i c a l d a t a o n l y , , mean a m p l i t u d e of c o n s t i t u e n t d e t e r m i n e d by a n a l y s i s of t i d a l r e c o r d s , <*. , phase a n g l e of c o n s t i t u e n t d e t e r m i n e d from t i d a l r e c o r d s and may be a d j u s t e d t o b e g i n the s e r i e s a t any t i m e . The t i d a l h e i g h t may be p r e d i c t e d w i t h good a c c u r a c y by u s i n g o n l y f o u r of the components l i s t e d i n F i g u r e 4 and t a k i n g the v a l u e of $ e q u a l t o u n i t y . These components are ^ A x . due t o the moon, due t o the sun, and K, and ^» due t o the moon's d e c l i n a t i o n . The s e r i e s t hen becomes I f a l l the r e m a i n i n g terms of the s e r i e s were i n phase a t M = +- M - t cos C k 0 5 5 0\ 0Y 0s 0\ «\ oo ^ U o o g o o o 0 o o v£> 0 o ^ > ^ > V V » ->0 .vf l HI. to « N 00 o 0 <D eg •o-o Q 0 M (Si 0 0 0 0 N Q ^ £ ^  ^  0 •— o o l/i eb CO j$ 0 >o «6 >. N. 8 »0 W- ^ *0 o o ft ^ >. tt ig ^ K> *S Oo > V> to .6 fv\ «d 1^ M ^- ^ to ^ - 0 > o r\ oo v> K ^ • o P -O 0* 9 N 0 N \o w» > 0» 00 ^ ^ K «v N 0 0 0 O > o • t o 0 <i 0 o W /V) v> S> ^ M 00 ^ ^ to >0 \p ^ o Q 0 ? 5 3 0 £ i CO s& N-^ 0 to 0 o 0» O 0 5 Q f l N 9 1^ 0 13 some time, the r e s u l t a n t e r r o r i n the model t i d e would be 14$ of the maximum range. Since these components w i l l , i n g e n e r a l , be out of phase w i t h each o t h e r , the r e s u l t a n t e r r o r w i l l be l e s s than 14$. The r e s u l t s of the t i d e computer are shown graph-i c a l l y i n F i g u r e 5 where the sequence f o r a s p r i n g t i d e (maximum range) are shown. When the M t and components are i n o p p o s i t i o n to each other, neap t i d e s (minimum range) r e s u l t . The d i u r n a l v a r i a t i o n ( d i f f e r e n c e s i n the height of the two succeeding h i g h waters) i s caused by the two d e c l i n a t i o n terms and i s a maximum when t h e i r e f f e c t i s a d d i t i v e . It can be shown that the t i d a l c y c l e w i l l never repeat i t s e l f . "Near r e p i t i t i o n " however, occurs f r e q u e n t l y , the most obvious case being the monthly r e p i t i t i o n of the s p r i n g and neap t i d e s . approximation of the valve opening r e q u i r e d to add or remove water from the model. Thus i f The r a t e of change of the t i d a l h e i g h t i s a f i r s t cos C ^ "t -*- °0 dl-t but where A i s s u r f a c e a r e a o f t h e model, so t h a t Q ~ A, a ^ C X J S Qoih -v- oc x ^ T h e r e f o r e t h e v a l v e s c a n be c o n t r o l l e d b y a s e r i e s s i m i l a r S o rv\tv\cx"\ «0%-i t o t h a t u s e d f o r t h e t i d a l h e i g h t c smut a t t e s t e x c e p t t h e components must be ~$jz r a d i a n s i n a d v a n c e o f the h e i g h t components and o f a l e n g t h p r o p o r t i o n a l t o A p u l l y a n d c a b l e s y s t e m , F i g u r e s 6 and 15, i s used, t o i n t e g r a t e t h e s e s e r i e s a n d t h e r e s u l t i s f e d d i r e c t l y t o the c o n t r o l v a l v e s i n t h e c a s e o f t h e d e r i v -a t i v e , and t o t h e c o n t r o l f l o a t and t h e t i d e r e c o r d e r , i n t h e c a s e o f t h e h e i g h t summation. Power f o r t h e t i d e c o m puter i s s u p p l i e d b y a o n e - q u a r t e r h o r s e p o w e r e l e c t r i c i n d u c t i o n m o t o r . By u s i n g c a b l e s t o sum t h e t i d a l components, a f u r t h e r maximum e r r o r 0.6$ i s i n t r o d u c e d , w h i c h i s c o n -s i d e r e d n e g l i g i b l e . S p u r g e a r s a r e employed t o p r o d u c e the a n g u l a r v e l o c i t y r a t i o between t h e component c r a n k s . Owing t o t h e expense o f p r e c i s e l y r e p r o d u c i n g a n g u l a r v e l o c i t i e s , maximum a l l o w a b l e e r r o r o f 0.0033$ was s e l e c t e d v a r b i t r a r i l y a nd t h e g e a r i n g d e s i g n e d w i t h i n t h i s l i m i t . The l o n g p e r i o d t i d a l components c a n be s e t on t h e computer m a n u a l l y a n d w i l l r e d u c e t h e e r r o r s i n t i d a l h e i g h t somewhat The t i d e computer may be s e t up as f o l l o w s : t h e TIDE COMPUTER H e i g h t I n t e g r a t i n g . Cable ± To C o n t r o l F l o a t and T i d e R e c o r d e r \ • Manual Adjustment . 5? t e e t h D e r i v a t i v e I n t e g r a t i n g Cable 59 M, 87 8 8 115. K . 118 1 1 9 1 2 3 o. Figure 6 15 a n g u l a r p o s i t i o n o f t h e components i s c a l c u l a t e d f o r t h e p r o t o t y p e t i m e a t w h i c h t h e e x p e r i m e n t i s t o b e g i n , t h e 5 T component i s l o c k e d i n a known p o s i t i o n , t h e r e m a i n i n g c r a n k s a d j u s t e d t o t h e i r p r o p e r r e l a t i v e p o s i t i o n s , a n d t h e d r i v i n g g e a r s a r e t h e n l o c k e d t o t h e i r s h a f t s . 3. CONTROL VALVES. S i n c e the m o t i o n a v a i l a b l e t o o p e r a t e the c o n t r o l v a l v e s was p r o p o r t i o n a l t o t h e d i s c h a r g e , v a l v e s h a v i n g a n e a r l y l i n e a r c h a r a c t e r i s t i c were r e q u i r e d . Two b r a s s s l e e v e v a l v e s w i t h r e c t a n g u l a r p o r t s were s p e c i a l l y made ( F i g u r e 7 ) b e c a u s e no s u i t a b l e t y p e i s a v a i l a b l e c o m m e r c i a l l y . The e q u a t i o n o f d i s c h a r g e f o r t h e v a l v e s i s where p o r t a r e a t h e d i s c h a r g e c o e f f i c i e n t f a c t o r p r o p o r t i o n a l t o t h e h e a d l o s s e s i n t h e a p p r o a c h p i p i n g . £ maximum a v a i l a b l e h e a d o f water. s o l v i n g f o r Q a n d e x p a n d i n g by t h e b i n o m i a l t h e o r e m , Thus i f X, i s s m a l l , t h e r e l a t i o n b etween Q and /S i s n e a r l y l i n e a r . The o b s e r v e d c h a r a c t e r i s t i c c u r v e s t a k e n Retainer , Cap Nut Packing Washer Sleeve CONTROL VALVE DESIGN F i g u r e 7 0 1 0 2 0 ' 3 0 l|.0 V a l v e O p e n i n g , D e g r e e s CHARACTERISTICS OP CONTROL VALVES F i g u r e 8 16 " i n s i t u " , t o g e t h e r w i t h t h e d r a w i n g s , a r e shown i n F i g u r e 8. The method o f c o n n e c t i n g t h e c o n t r o l v a l v e s t o t h e d e r i v -a t i v e c a b l e and s e r v o m otor i s shown s c h e m a t i c a l l y i n F i g u r e 9. 4. CONTROL FLOAT AND SERVOMECHANISM. The c o n t r o l f l o a t i s a m e t a l box w h i c h f l o a t s i n a s t i l l i n g b a s i n b u i l t i n t o the downstream end o f t h e m o d el, F i g u r e 16. The h e i g h t o f the t i d e i n t h e m odel i s com-p a r e d w i t h t h e computed t i d e b y a p r o b e arm c o n n e c t e d t o t h e t i d e c o m p u t e r o u t p u t . T h r e e p l a t i n u m w i r e s f o r m i n g t h e p r o b i n g e l e m e n t d i p i n t o t h e m e r c u r y cup on t h e c o n t r o l f l o a t . The s e r v o - m e c h a n i s m i s a r r a n g e d t o g i v e s t e p p e d p r o p o r t i o n a l c o n t r o l about t h e c e n t r e p r o b e as shown i n F i g u r e 10. When the t i d e i s i n e r r o r s u c h t h a t e i t h e r t h e u p p e r probe i s t o u c h i n g t h e m e r c u r y s u r f a c e o r the l o w e r p robe i s f r e e o f t h e m e r c u r y s u r f a c e , t h e v o l t a g e a p p l i e d t o t h e s e r v o - m o t o r i s i n c r e a s e d above t h a t a p p l i e d when t h e s u r f a c e i s h u n t i n g a b o u t t h e end o f t h e c e n t r e p r obe a n d a more r a p i d c o r r e c t i o n r e s u l t s . When t h e r i v e r d i s c h a r g e i s v a r i e d , t h e s e r v o -m o t o r w i l l move the f u l c r u m , F i g u r e 9, t o a new mean p o s i t i o n a n d f u r t h e r o s c i l l a t i o n about t h i s p o s i t i o n i s due t o v a r i a t i o n i n t h e model s u r f a c e a r e a w i t h t i d a l h e i g h t , F i g u r e 11, a n d t o n o r m a l h u n t i n g . S a l t Water I n l e t V a l v e S e r v o - m o t o r Prom T i d e Computer F u l c r u m j M i x e d Water u t l e t V a l v e S c h e m a t i c D i a g r a m o f CONTROL VALVE LINKAGE F i g u r e 9 I H.F. Motor D.P.'O.T. Upper L i m i t \ S w i t c h \ Lowei* L i m i t S w i t c h Probes Mercury-Cup N.C.- N o r m a l l y C l o s e d C o n t a c t ) R e f e r e d t o Probe N.O.- N o r m a l l y Open C o n t a c t ) P o s i t i o n Showen D.P.D.T.- Double P o l e Double Throw R e l a y D.P.S.T.- Double P o l e S i n g l e Throw R e l a y SERVO-MOTOR CONTROL CIRCUIT F i g u r e 10 F i g u r e 11 17 The s e r v o - m o t o r u s e d i s a o n e - f i f t e e n t h h o r s e s h u n t wound m o t o r . T h i s m otor has a b u i l t i n s p e e d r e d u c e r t o g i v e an o u t p u t s p e e d o f n i n e r e v o l u t i o n s p e r m i n u t e . T h i s i s c o n n e c t e d b y a s p r o c k e t a n d c h a i n t o a s p r o c k e t w i t h a t h r e a d e d hub w h i c h engages a screw a t t a c h e d t o t h e f u l c r u m . L i m i t s w i t c h e s a r e a t t a c h e d t o the f u l c r u m t o g i v e a maximum l i m i t t o i t s movement. 5. TIDE RECORDER. T h i s - d e v i c e r e c o r d s t h e computed t i d e , a c t u a l t i d e , and p r o t o t y p e t i m e on a s t r i p o f a d d i n g machine t a p e . The r e c o r d e r i s o p e r a t e d b y a s e l s y n m o t o r - g e n e r a t o r s y s t e m f r o m t h e t i d e c o m p u t e r . D u r i n g e x p e r i m e n t s th e computed t i d e o n l y i s r e c o r d e d , t h e a c t u a l t i d e b e i n g r e c o r d e d when a c h e c k on t h e a c c u r a c y o f t h e c o n t r o l mechanism i s r e q u i r e d . A p h o t o g r a p h i s shown i n F i g u r e 17. 6. RIVER HEADWORKS. R i v e r f l o w i s m a n u a l l y c o n t r o l l e d i n t h e model, u s i n g a 30 d e g r e e Vee n o t c h w e i r d i s c h a r g i n g i n t o a b a s i n and o v e r f l o w i n g i n t o t h e Somass R i v e r c h a n n e l , F i g u r e 14. R e c o r d s o f d a i l y o b s e r v a t i o n s o f t h e d i s c h a r g e o f t h e S p r o a t a n d Stamp R i v e r s , w h i c h j o i n t o f o r m t h e Somass, a r e a v a i l -a b l e f r o m t h e Water R e s o u r c e s a n d D r a i n a g e B o a r d , and i n d i c a t e t h a t a d j u s t m e n t a t i n t e r v a l s o f ijt h o u r s ( w e e k l y i n t h e p r o t o t y p e ) i s s u f f i c i e n t , e x c e p t i n t i m e s o f f r e s h e t . 1 8 V e r y a c c u r a t e r e p r o d u c t i o n o f r i v e r f l o w c a n be o b t a i n e d i n t h i s manner w i t h r e l a t i v e l y l i t t l e e x p e n s e . INSTRUMENTATION 1 . METHODS OF OBSERVATION. C u r r e n t d a t a can be o b t a i n e d b y a c o m m e r c i a l l y a v a i l a b l e i n s t r u m e n t , t h e " M i d g e t C u r r e n t M e t e r " , o r by p h o t o g r a p h i n g n e u t r a l l y b u o y a n t d r o p l e t s o f c a r b o n t e t r a -c h l o r i d e a n d p e t r o l e u m e t h e r . The c u r r e n t meter w i l l g i v e good r e s u l t s a t v e l o c i t i e s above 0 . 1 f e e t p e r s e c o n d . The p h o t o g r a p h i c method g i v e s e x c e l l e n t a c c u r a c y and may be u s e d w i t h v e r y low v e l o c i t i e s i n c o n f i n e d a r e a s s i n c e t h e dye has a n e g l i g i b l e e f f e c t on t h e f l o w p a t t e r n . I t r e q u i r e s c o n s i d e r a b l e t i m e a n d e q uipment however. Flow p a t h s a r e t o be o b s e r v e d b y the i n t r o d u c t i o n o f a dye w i t h i t s d e n s i t y a d j u s t e d t o c o r r e s p o n d t o a s p e c i f i c s a l i n i t y , o r , i n t h e c a s e o f sewage d i s p o s a l s t u d i e s , t h e d e n s i t y o f t h e sewage. S a l i n i t y i s t o be d e t e r m i n e d c h e m i c a l l y f r o m s m a l l samples o f w a t e r t a k e n f r o m t h e model d u r i n g o p e r a t i o n . The w a t e r s a m p l e r shown i n F i g u r e 1 2 i s u s e d t o remove t h e s a m p l e s . The sample i s t a k e n by i m m e r s i n g t h e w i t h d r a w a l tube t o a p r e d e t e r m i n e d p o s i t i o n i n t h e model, a n d a p p l y i n g a vacuum t o t h e r i n s e b o t t l e a t t h e t i m e t h e sample i s r e q u i r e d . The w a t e r sample i s t h u s drawn t h r o u g h t h e To Vacuum System Rubber T u b i n g Withdraw! Tube S c a l e : A c t u a l s i z e One u n i t o f WATER SAMPLER F i g u r e 12 w i t h d r a w a l t u b e and sample b o t t l e , a n d i n t o t h e r i n s e b o t t l e u n t i l t h e w a t e r l e v e l r e a c h e s t h e n y l o n b a l l c h e c k v a l v e . The f o r c e s o f t h e w a t e r on n y l o n b a l l cause i t t o c l o s e t h e end o f t h e c o p p e r t u b e t h u s p r e v e n t i n g f u r t h e r w i t h d r a w a l o f w a t e r . The r i n s e b o t t l e i s employed t o make c e r t a i n t h a t no r e s i d u a l w a t e r f r o m t h e p r e v i o u s sample i s p r e s e n t . The r i n s e b o t t l e and sample b o t t l e a r e t h e n r e -moved f r o m t h e i r r u b b e r s t o p p e r s , t h e r i n s e w a t e r thrown away and t h e sample k e p t f o r a n a l y s i s . I n p r a c t i c e t h e w a t e r s a m p l e r s a r e t o be u s e d i n banks o f f i v e o r more t o c o r r e s p o n d t o t h e method o f t a k i n g w a t e r samples i n n a t u r e where s e v e r a l w a t e r " b o t t l e s " a r e l o w e r e d on a c a b l e . 2 . VERIFICATION. The model w i l l be v e r i f i e d b y c o m p a r i n g t h e 7 d i s t r i b u t i o n o f s a l i n i t y w i t h t h a t o b s e r v e d i n n a t u r e (#) u n d e r c o m p a r a b l e c o n d i t i o n s o f t i d e a n d r i v e r d i s c h a r g e . I t w i l l be n e c e s s a r y t o a d j u s t t h e r o u g h n e s s o f t h e f i x e d b e d p o r t i o n o f the model i n o r d e r t o g i v e a r e a l i s t i c r e -p r o d u c t i o n o f t u r b u l e n c e . The v a l i d i t y o f t h e r e s u l t s p e r t a i n i n g t o bed movement w i l l be c h e c k e d b y s i m u l a t i n g n a t u r a l c o n d i t i o n s e x i s t i n g a t some t i m e i n t h e p a s t and o p e r a t i n g t h e model so as t o r e p r o d u c e some phenomena w h i c h has b e e n o b s e r v e d t o c c u r . A c o m p a r i s o n o f r e s u l t s o b t a i n e d i n t h e model w i t h t h e n a t u r a l phenomena w i l l p r o v i d e an i n d e x o f a c c u r a c y o f h e d movement. DISCUSSION I t i s p r o p o s e d t o s t u d y t h e h a r b o u r o c e a n o g r a p h i c -a l l y as a n example o f a t i d a l e s t u a r y , a n d t o i n v e s t i g a t e t h e c o n s e q u e n c e s o f p r o p o s e d p h y s i c a l changes i n t h e r i v e r bed, and i t s a p p r o a c h t o t h e h a r b o u r . T h i s r e q u i r e s t h a t t h e o c e a n o g r a p h i c s t r u c t u r e a n d i t s v a r i a t i o n s i n r e l a t i o n t o t i d e a n d r i v e r d i s c h a r g e be i n v e s t i g a t e d by o b s e r v i n g t h e d i s t r i b u t i o n o f s a l i n i t y , w h i c h c o r r e s p o n d s t o t h e d e n s i t y d i s t r i b u t i o n s i n c e t h e r e w i l l be no t e m p e r a t u r e g r a d i e n t s . C o r r e s p o n d i n g s t u d i e s o f t h e c u r r e n t s a r e r e -q u i r e d f o r t h e e x p r e s s i o n o f t h e m e c h a n i c s o f t h e s y s t e m . Bed movement s t u d y i s r e q u i r e d t o d e t e r m i n e t h e c o n s e q u e n c e s o f t h e p r o p o s e d e n g i n e e r i n g w o r k s . A t p r e s e n t t h e model i s r e a d y f o r v e r i f i c a t i o n a n d e x p e r i m e n t . A c r i t e r i o n f o r t h e s c a l i n g o f d e n s i t y d i f f e r e n c e b etween s a l t and f r e s h w a t e r may be e s t a b l i s h e d as f o l l o w s : I n K e u l e g a n ' s p r e s e n t a t i o n o f t h e R i c h a r d s o n - P r a n d t l number f o r t u r b u l e n t exchange o f d e n s i t y a t t r i b u t e where 7^  i s t h e c o e f f i c i e n t o f d i f f u s i o n o f s a l t , and i s t h e c o -e f f i c i e n t o f eddy v i s c o s i t y , t h e r a t e o f d o i n g w o r k p e r u n i t volume by s h e a r s t r e s s e s i s shown t o be and t h e r a t e o f d o i n g w o r k p e r u n i t volume a g a i n s t g r a v i t y i s shown t o be I n o r d e r t o have t h e same r e l a t i v e amount o f v e r t i c a l t r a n s f e r o f s a l t i n b o t h m o d e l a n d p r o t o t y p e , t h e v e r t i c a l v e l o c i t y o f s a l t t r a n s f e r , a n d hence t h e r a t e o f d o i n g w o r k a g a i n s t g r a v i t y on a p e r u n i t volume b a s i s i n t h e m o d e l , must be i n c r e a s e d i n t h e r a t i o o f t h e v e r t i c a l t o t h e h o r i z o n t a l s c a l e s , *«-/xr as 4£ - t Wit 4* A s s u m i n g t h a t the r a t i o of t h e w o r k done a g a i n s t g r a v i t y t o t h a t d i s s i p a t e d b y t h e v i s c o u s a c t i o n i s the same f o r s i m i l a r f l o w c o n d i t i o n s i n b o t h model and p r o t o -t y p e , so t h a t ±jv m ic a t Jit dX t h e n 22 or f r o m w h i c h s i n c e t h e F r o u d i a n model s c a l e s a r e u s e d i n w h i c h VR » W r i t t e n f o r t h e p r o t o t y p e , t h i s e q u a t i o n becomes t a k i n g r a t i o s Nov/ i f "^Ai i s "the same f o r b o t h model and p r o t o t y p e , t h e n T h e r e f o r e t h e d e n s i t y d i f f e r e n c e s h o u l d be d i m i n i s h e d i n t h e r a t i o o f t h e s c a l e d i s t o r t i o n i n o r d e r t o g i v e c o m p a r a b l e d e n s i t y v s . d e p t h c u r v e s f o r b o t h m o d e l and p r o t o t y p e . 23 The v a l i d i t y o f t h e above r e s u l t depends on two a s s u m p t i o n s w h i c h a r e n o t "a p r i o r i " c o r r e c t . T h e s e a r e 1. The r a t i o o f t h e work done a g a i n s t g r a v i t y t o t h a t d i s s i p a t e d b y v i s c o u s a c t i o n i s t h e same f o r s i m i l a r f l o w c o n d i t i o n s i n b o t h model a n d p r o t o t y p e , a n d 2. The r a t i o ^/z) i s t h e same f o r b o t h model a n d p r o t o -t y p e . The a s s u m p t i o n 1. i s p r o b a b l y i n e r r o r b e c a u s e f a s t -e r r e l a t i v e movement i s r e q u i r e d i n t h e m o d e l . T h e r e f o r e a g r e a t e r p r o p o r t i o n o f t h e work done by s h e a r s t r e s s e s w o u l d be c o n v e r t e d i n t o h e a t e n e r g y . I f s u c h i s t h e c a s e a f u r t h e r s m a l l r e d u c t i o n i n t h e d e n s i t y s c a l e r a t i o i s r e q u i r e d . The v a l i d i t y o f a s s u m p t i o n 2. c a n o n l y be p r o v e n by e x p e r i m e n t . The above r e s u l t i s i n agreement w i t h von A r x ( 8 ) , who s u g g e s t s t h e same r e s u l t on t h e b a s i s o f e x p e r i m e n t s w i t h d e n s i t y s t r a t i f i e d m o d e l s . The use o f a p u l l y a n d c a b l e s y s t e m t o i n t e g r a t e t h e t i d e has the f o l l o w i n g d i s a d v a n t a g e s ; 1. R e q u i r e s a g r e a t d e a l o f s p a c e f o r t h e c a b l e s . 2. I s d i f f i c u l t t o s e t t o a s p e c i f i c i n s t a n t o f t i m e when b e g i n n i n g an e x p e r i m e n t . The o p e r a t o r c a n n o t be c e r t a i n o f a n i n i t i a l c r a n k s e t t i n g w i t h i n a b o u t t h r e e d e g r e e s i n a n g l e . 3. E l a s t i c i t y and c l e a r a n c e s i n t h e mechanism r e s u l t s i n a s l i g h t l y d i s t o r t e d o u t p u t c u r v e . ?v rhile t h e e f f e c t s o f t h e above p o i n t s a r e e x p e c t e d t o have n e g l i g i b l e e f f e c t on the e x p e r i m e n t a l r e s u l t s , t h e y a r e n o t d e s i r a b l e a n d s h o u l d n o t be p r e s e n t i n f u t u r e d e s i g n s o f t i d e c o m p u t e r s . The c o n t r o l v a l v e s have f u n c t i o n e d w e l l b u t do l e a a t t h e p a c k i n g g l a n d . The o r i g i n a l d e s i g n c a l l e d f o r a n "0 r i n g " s e a l i n p l a c e o f t h e p a c k i n g w asher, however, t h e v a l v e s h a f t was p i t t e d d u r i n g t h e b r a z i n g o f t h e v a l v e s l e e v e ^component and a g r a p h i t e i m p r e g n a t e d c o t t o n w a s h e r had t o be u s e d b e c a u s e o f r o u g h s u r f a c e s . The v a l v e s h a f t s h o u l d have b e e n made e x t r a l a r g e , a f i n e s u r f a c e t u r n e d a f t e r b r a z i n g , and an H 0 r i n g " f i t t e d . O r i g i n a l c l e a r a n c e between t h e 5.187 i n c h d i a m e t e r v a l v e s l e e v e and t h e v a l v e body was a b o u t 0.003 i n c h e s . T h i s h a d t o be i n c r e a s e d b y l a p p i n g b e f o r e s a t i s f a c t o r y o p e r a t i o n was o b t a i n e d . The v a l v e c h a r a c t e r i s t i c , F i g u r e 8, c o u l d be made l i n e a r by p r o p e r l y s h a p i n g t h e v a l v e p o r t s . The use o f e l e c t r o n i c d e v i c e s has many a d v a n t a g e s i n h y d r a u l i c model s t u d i e s and c o u l d have b e e n u s e d h e r e t o a d v a n t a g e h a d the a u t h o r ' s knowledge a n d t h e f u n d s a v a i l -a b l e , been s u f f i c i e n t . A t i d e c o mputer a d a p t a b l e t o any h y d r a u l i c model c o u l d be made u s i n g t h e d e s i g n o f L o r d K e l v i n ' s t i d e p r e -d i c t i n g machine as a b a s i s , b u t h a v i n g t h e o u t p u t t a k e n o f f 25 i n t h e f o r m o f a v o l t a g e w h i c h c o u l d he u s e d t o o p e r a t e t h e c o n t r o l v a l v e s . The c a b l e s c o u l d be r e p l a c e d b y a s c o t c h yoke on e a c h component c r a n k c o n n e c t e d t o a v a r i a b l e r e s i s -t a n c e . These r e s i s t a n c e s c o u l d be summed by a s e r i e s c i r c u i t a n d compared w i t h t i d a l h e i g h t . The c o n t r o l f l o a t c o u l d be r e p l a c e d w i t h a p r obe i n w h i c h a 0.002 i n c h w i r e i s t h e o n l y m a t e r i a l i n c o n t a c t w i t h t h e model w a t e r s u r f a c e . A p r o b e o f t h i s t y p e i s c u r r e n t l y b e i n g d e v e l o p e d a t t h e N a t i o n a l R e s e a r c h C o u n c i l , F r a s e r R i v e r M o d e l , and shows p r o m i s e . I n o p e r a t i o n t h e end o f t h e p r o b e w i r e h u n t s c o n t i n u o u s l y a b o u t t h e w a t e r s u r f a c e . An a c c u r a c y o f "t 0.003 i n c h e s i s t h o u g h t t o be o b t a i n a b l e i n t h i s way. The p r obe c o u l d be c o n n e c t e d t o a p o t e n t i o m e t e r , w h i c h compared w i t h t h e t i d e c o mputer o u t p u t , w o u l d o p e r a t e t h e c o n t r o l v a l v e s t h r o u g h a s e r v o - m e c h a n i s m . The method d e s c r i b e d above has none o f t h e d i s -a d v a n t a g e s o f t h e p r e s e n t s y s t e m and i s c o m p l e t e l y a d a p t a b l e . ACKNOWLEDGMENT The model was c o n s t r u c t e d on t h e p r e m i s e s o f t h e - P a c i f i c B i o l o g i c a l S t a t i o n o f t h e F i s h e r i e s R e s e a r c h B o a r d , a t Nanaimo, B. C., a n d t h e machine work done i n t h e shop o f t h e D e p a r t m e n t o f M e c h a n i c a l E n g i n e e r i n g a t the U n i v e r s i t y 26 o f B r i t i s h C o l u m b i a . The a u t h o r w i s h e s t o e x p r e s s h i s s i n c e r e g r a t i t u d e t o Mr. P r e n t i c e B l o e d e l o f B l o e d e l , S t e w a r t , and W e l c h , L t d . , who p r o v i d e d v a l u a b l e f i e l d d a t a and t h e B l o e d e l , S t e w a r t , a n d W e l c h F e l l o w s h i p i n O c e a n o g r a p h y w h i c h made t h i s r e -s e a r c h p o s s i b l e ; t o D r . J . P. T u l l y , D i r e c t o r o f t h e P a c i f i c O c e a n o g r a p h i c Group, F i s h e r i e s R e s e a r c h B o a r d , u n d e r whose d i r e c t i o n t h i s work was c a r r i e d o u t ; and t o P r o f e s s o r W. 0 . Richmond o f t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , f o r t h e many s u g g e s t i o n s r e g a r d i n g t h e m e c h a n i c a l a s p e c t s o f the model an d f o r i n v a l u a b l e c r i t i c i s m o f t h e m a n u s c r i p t . The Model I n Operation Tide r e c o r d e r i s on the l e f t , c o n t r o l valves behind the man. Dimensions of the model are 25 f e e t by 7 j f e e t T The Model The b o t t l e s i n the foreground are p a r t of the dye i n j e c t o r s used f o r c u r r e n t observations FIGURE 13 T i d e F l a t A r e a T h i s a r e a i s b u i l t up i n s a n d and ' f i x e d ' w i t h a s p r a y o f cement an d w ater R i v e r Headworks R i v e r f l o w i s r e g u l a t e d by v a r y i n g t h e h e a d b e h i n d the w e i r . FIGURE 14 T i d e Computer The i n d u c t i o n motor i s v i s i b l e on the r i g h t  T h i s d r i v e s t h e computer by a l e a t h e r b e l t . T i d e Computer The c u r v e o f t i d a l h e i g h t i s t a k e n f r o m t h e u p p e r  c r a n k s , t h e d e r i v a t i v e f r o m t h e l o w e r . No d e r i v a t i v e  c r a n k was p l a c e d on t h e l e f t h a n d c r a n k (o,) b e c a u s e  l e n g t h was s h o r t . FIGURE 15 S t a n d p i p e s V e r t i c a l v e l o c i t y d i s t r i b u t i o n can be p a r t l y  c o n t r o l l e d by the shape of the openings C o n t r o l F l o a t 0.005 i n c h copper w i r e s connect moving p a r t s t o  remainder of e l e c t r i c a l c i r c u i t .  The p o s i t i o n of the probe arm i s c o n t r o l l e d by  the T i d e Computer. FIGURE 16 Water Sampler The wooden base i s used f o r s t o r a g e o n l y , When i n use  the copper tubes are immersed i n the model t o a p r e d e t e r m i n e d d e p t h . -T i d e R e c o r d e r T h i s i s used t o r e c o r d the computed t i d e d u r i n g an e x p e r i m e n t . P r o t o t y p e hours are marked: on t h e tape end a c o u n t e r r e c o r d s  the d a t e . A c t u a l model t i d e can be t r a c e d on the under s i d e of  the tape f o r comp a r i s o n . The t i d e r e c o r d e r i s d r i v e n by a  S e l s y n m o t o r - g e n e r a t o r from the t i d e computer. FIGURE 17 27 L I S T OP WORKS CONSULTED 1. A l l e n , J . 2. B l e n c h , T. S c a l e Models i n H y d r a u l i c E n g i n e e r i n g , Longmans, G r e e n & Co., Lon d o n , 1947. The H y d r a u l i c s o f S e d i m e n t B e a r i n g C a n a l s  a n d R i v e r s , E v a n s I n d u s t r i e s L t d . , V a n c o u v e r , 1950. 3. Buckingham E . S i m i l a r Systems and D i m e n s i o n a l a q u a t i o n s P h y s i c s Review, 4. S e r 2. pp 345-376, O c t . , 1914. 4. K a l i n s k i , A.A R e l a t i o n o f t h e S t a t i s t i c a l T h e o r y o f T u r b u l e n c e t o H y d r a u l i c s , T r a n s . A. S. C. E . , V o l . 105 ( 1 9 4 0 ) , p. 1547 5. K e u l i g a n , G. 6. Schurman, P. Mod e l Laws f o r D e n s i t y C u r r e n t s , f r o m t h e P r o c e e d i n g s o f t h e C o l l o q u i e m on t h e F l u s h - o f E s t u a r i e s . Woods H o l e Oceano-g r a p h i c I n s t i t u t i o n , Woods H o l e , Mass. U.S.A. 1950. Manual o f Harmonic A n a l y s i s and P r e - d i c t i o n o f T i d e s , U.S. Department o f Commerce, S p e c i a l Pub. No. 98. 1940. 7. T u l l y , J o h n P O c e a n o g r a p h y and P r e d i c t i o n o f P u l p M i l l P o l l u t i o n i n A l b e r n i I n l e t , F i s h . R es. Bd. Can., B u l l . 83, 1949. 8. v o n A r x , S y n o p t i c M o d e l s o f t h e C i r c u l a t i o n o f  E s t u a r i e s , f r o m t h e P r o c e e d i n g s o f t h e C o l l o q u i u m on t h e F l u s h i n g o f E s t u a r i e s . Woods H o l e O c e a n o g r a p h i c I n s t i t u t i o n , Woods H o l e , Mass. U.S.A. 1950, 

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