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A parametric study of rigid body-viscous flow interaction Moorty, Shashi

Abstract

This thesis presents the numerical solution for two-dimensional incompressible viscous flow over a rigid bluff body which is elastically supported or alternately undergoing a specified harmonic oscillations. Solutions for the related associate flow in which the body is at rest in a two-dimensional incompressible time-dependent viscous flow have also been -obtained. This work is an extension of the work by Pattani [19] to include the effect of a steady far field flow on an oscillating body. The numerical model utilizes the finite element method based on a velocity-pressure primitive variable representation of the complete Navier-Stokes equations. Curved isoparametric elements with quadratic interpolation for velocities and bilinear interpolation for pressure are used. Nonlinear boundary conditions on the moving body are represented to the first order in the body amplitude parameter. The method of averaging is used to obtain the resulting periodic motion of the fluid. Three non-dimensional parameters are used to completely characterise the flow problem: the frequency Reynolds number Rω , the Reynolds number of steady flow Rℯ₁ and the Reynolds number for time-dependent flow Rℯ₂. Numerical results are obtained for a circular body, a square body and an equilateral triangular body. A parametric study is conducted for different values of the Reynolds numbers in the viscous flow regime. In all cases, results are obtained for streamlines, streaklines, added mass, added damping, added force and the drag coefficients. The limiting cases of steady flow over a fixed body and an oscillating body in a stationary fluid are checked with known results. Results for the associated flow are also obtained. The transformations derived, between the two associated flows are checked. Good agreement is obtained between the present results and other known results.

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