The figure below comes from a study of under-resolved computations of periodic shear layers using a Godunov/Projection method. Of major interest is the presence of spurious vortices, which, once they have appeared, become indistinguishable from the true physical vortices in the flow. Continuing research on this problem has shown that this phenomenon is not restricted to the Godunov/Projection method but rather is a feature of a wide variety of numerical approaches including spectral, ENO, and centered-difference methods. In fact, all methods tested so far exhibit similar types of behavior, thus it is of major importance to be able to identify and if possible elminate the cause of these sorts of effects in numerical simulations.

SPURIOUS

Impact:

Because of the constraints on current computing power, under-resolution of numerical fluid flow calculations is often unavoidable. Therefore the ability to understand and identify the effects of under-resolution is central to any computing effort. Effective strategies for implementing adaptive mesh refinement (AMR) for incompressible flow calculations will also require this ability so that resolution can be increased before spurious features are introduced into the simulation.

For details on the completed research see

Performance of Under-resolved Two-Dimensional Incompressible Flow Simulations,
Journal of Computational Physics, v. 121, November 1995
by David L. Brown and Michael L. Minion

Performance of Under-resolved Two-Dimensional Incompressible Flow Simulations, II
Journal of Computational Physics, in submission
by Michael L. Minion and David L. Brown

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