Use of Improved Far -Field Boundary Conditions to Compute External Flows on Reduced Domains

We have also used this computational approach to study, for the first time, flow past a convex axisymmetric body formed by a finite paraboloid with a paraboloidal surface closing the aperture. Converged flows were computed for three different aspect ratios up to a Reynolds number (Re) of 200. For sufficiently small Re, there is no separation. For an intermediate range of Re, the separation point moves from the rear stagnation point towards the edge of the body as Re increases. Beyond some Re, the computed separation circle lies between the edge and nearest grid point, for all grid spacings considered. The length of the separated flow region varies approximately with a fractional power of the logarithm of the Reynolds number. The computational advantages of the present approach are demonstrated by comparing memory usage and runtime for solutions of comparable accuracy. When the system of nonlinear algebraic equations is solved by Newton iteration, memory usage and runtime are reduced by about 70% compared to computations using Neumann and free-stream Dirichlet boundary conditions.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Mechanical Engineering

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Mantle, William Joseph

Contributors dc:contributor

• Pearlstein, Arne J.

• Applied Mechanics

Language dc:language

eng

Identifier

(MiAaPQ)AAI9990212

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/84013