UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Variational problems with thin obstacles Richardson, David

Abstract

In this thesis the solution to the variational problem of Signorini is studied, namely: (i) Δv = 0 in Ω; (ii) v ≥ ѱ on əΩ; (iii) əv/əѵ ≤ g on əΩ; (iv) (v- ѱ) (əv/əѵ – g) = 0 on əΩ where Ω is a domain in R[sup n], and v is the unit inner normal vector to əΩ. In the case n = 2 a regularity theorem is proved. It is shown that if ѱ Є C[sup 1,α] (əΩ), g Є Lip α(əΩ) then v Є C[sup 1,α] (əΩ) if α < 1/2 . An example is given to shown that this result is optimal. The method of proof relies on techniques of complex analysis and therefore does not extend to higher dimensions. For n > 2 the case where Ω, is unbounded, or equivalently, where ѱ is unbounded in a neighbourhood of some point of əΩ is considered. This is a situation where known existence theorems do not apply. Some sufficient conditions for the pair (ѱ,g) are derived that will ensure the existence of a solution in this case, thereby extending some results obtained by A. Beurling and P. Malliavin in the two dimensional case. The proof involves a variational problem in a Hilbert space analogous to the one considered by Beurling and Malliavin, and some pointwise estimates of Riesz transforms.

Item Media

Item Citations and Data

Rights

For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.

Usage Statistics