Stochastic coherent adaptive large eddy simulation method

In this paper we propose a novel approach called the stochastic coherent adaptive large eddy simulation (SCALES) method which takes advantage of both the coherent vortex simulation (CVS) and large eddy simulation (LES) methods. With the SCALES method a wavelet filter is applied to a turbulent field such that the maximum number of modes are resolved in the simulation, given the balance between computing resources and user defined acceptable simulation error. As with CVS, the wavelet thresholding filter will allow a SCALES simulation to resolve and "track" the coherent energetic structures in a turbulent flow field. The wavelet filter compression in SCALES will be substantially greater than the "ideal" wavelet compression used in CVS, making it cost effective for simulating high Re number flows. The SCALES methodology will simulate the most important modes given the resources available. Because of the higher wavelet compression the subgrid scales (SGS) in a SCALES simulation will contain both coherent and incoherent modes like with LES. In this work the SCALES method is presented for both velocity and vorticity space wavelet filtering. A novel coherency diagram of a turbulent field is introduced to present the physical relationships between direct numerical simulation and different large eddy capturing methods. In this work we show that with both LES filtering and SCALES filtering the residual SGS field contains both coherent and incoherent parts and that with both methodologies the total SGS dissipation is dominated by the coherent part of the SGS field. A possible implementation of the SCALES methodology for incompressible turbulent flows is also discussed. (C) 2004 American Institute of Physics.