Commutation error mitigation in variable-resolution PANS closure: Proof of concept in decaying isotropic turbulence
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abstract
Two quintessential attributes desired in variable-resolution (VR) bridging turbulence calculations are (i) ability to perform flow simulations at any prescribed level of resolution with the highest possible fidelity; and (ii) capability to vary the resolution in space and time while retaining high degree of physical accuracy through out the computational domain. Many VR models strive to satisfy the first requirement and have been successful to varying degrees. Spatio-temporal variation in resolution, the very attribute that make VR methods attractive for practical application, renders closure modeling rather complicated due to the so-called commutation error. In this paper, in the context of partially-averaged Navier-Stokes (PANS) VR approach, we develop a physics-based closure model for the commutation residual arising from spatio-temporal variation in flow resolution. The PANS model is then tested in a decaying isotropic turbulence flow field. It is demonstrated that (i) in constant resolution simulations, PANS achieves the prescribed resolution level and adequately captures the corresponding energy spectrum; and (ii) when the resolution is varied suddenly during the course of a simulation, the commutation model comes into effect yielding the required change in the calculations. Copyright 2011 by S. Wallin and S.S. Girimaji. Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.
