Far Field Conditions for Subsonic Flows with Small Superimposed Harmonic Oscillations.
Abstract
For numerical work one needs boundary conditions (so called far field conditions) at the outer edge (or surface) of the region of the flow field for which the computations are carried out. In oscillatory flows with higher frequencies and Mach number close to 1 these conditions become crucial and the formulation in use at present which is patterned after far field conditions in steady flows becomes impractical if not useless. The far field conditions express the fact that no waves coming from infinity are present. Mathematically this appears in the form of the requirement that the far field can be represented by a superposition of particular solutions which represent outgoing waves. On this basis one obtains by the application of Green's formula a number of integral conditions. An example shows that even with this formulation one will encounter numerical difficulties (because of latent standing waves) if one tries to solve the flow equations by iteration. Fortunately the new far field conditions are well suited to a solution of the problem by direct elimination, possibly combined with a refinement of the results by the multigrid method of Brand.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1979
- Accession Number
- ADA077693
Entities
People
- Karl G. Guderley
Organizations
- University of Dayton