Unpublished,

Viscous flows in corner regions: Singularities and hidden eigensolutions

, and .
(Jun 18, 2009)

Abstract

Numerical issues arising in computations of viscous flows in corners formedby a liquid-fluid free surface and a solid boundary are considered. It is shownthat on the solid a Dirichlet boundary condition, which removes multivaluednessof velocity in the `moving contact-line problem' and gives rise to alogarithmic singularity of pressure, requires a certain modification of thestandard finite-element method. This modification appears to be insufficientabove a certain critical value of the corner angle where the numerical solutionbecomes mesh-dependent. As shown, this is due to an eigensolution, which existsfor all angles and becomes dominant for the supercritical ones. A method ofincorporating the eigensolution into the numerical method is described thatmakes numerical results mesh-independent again. Some implications of theunavoidable finiteness of the mesh size in practical applications of the finiteelement method in the context of the present problem are discussed.

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