Oleg V. Vasilyev
University of Colorado Boulder
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Oleg V. Vasilyev.
Physics of Fluids | 2001
Grégoire Winckelmans; Alan A. Wray; Oleg V. Vasilyev; Hervé Jeanmart
Large-eddy simulation (LES) with regular explicit filtering is investigated. The filtered-scale stress due to the explicit filtering is here partially reconstructed using the tensor-diffusivity model: It provides for backscatter along the stretching direction(s), and for global dissipation, both also attributes of the exact filtered-scale stress. The necessary LES truncations (grid and numerical method) are responsible for an additional subgrid-scale stress. A natural mixed model is then the tensor-diffusivity model supplemented by a dynamic Smagorinsky term. This model is reviewed, together with useful connections to other models, and is tested against direct numerical simulation (DNS) of turbulent isotropic decay starting with Re-lambda=90 (thus moderate Reynolds number): LES started from a 256(3) DNS truncated to 64(3) and Gaussian filtered. The tensor-diffusivity part is first tested alone; the mixed model is tested next. Diagnostics include energy decay, enstrophy decay, and energy spectra. After an initial transient of the dynamic procedure (observed with all models), the mixed model is found to produce good results. However, despite expectations based on favorable a priori tests, the results are similar to those obtained when using the dynamic Smagorinsky model alone in LES without explicit filtering. Nevertheless, the dynamic mixed model appears as a good compromise between partial reconstruction of the filtered-scale stress and modeling of the truncations effects (incomplete reconstruction and subgrid-scale effects). More challenging 48(3) LES are also done: Again, the results of both approaches are found to be similar. The dynamic mixed model is also tested on the turbulent channel flow at Re-tau=395. The tensor-diffusivity part must be damped close to the wall in order to avoid instabilities. Diagnostics are mean profiles of velocity, stress, dissipation, and reconstructed Reynolds stresses. The velocity profile obtained using the damped dynamic mixed model is slightly better than that obtained using the dynamic Smagorinsky model without explicit filtering. The damping used so far is however crude, and this calls for further work
International Journal of Computational Fluid Dynamics | 2003
Oleg V. Vasilyev
A dynamically adaptive numerical method for solving multi-dimensional evolution problems with localized structures is developed. The method is based on the general class of multi-dimensional second-generation wavelets and is an extension of the second-generation wavelet collocation method of Vasilyev and Bowman to two and higher dimensions and irregular sampling intervals. Wavelet decomposition is used for grid adaptation and interpolation, while O ( N ) hierarchical finite difference scheme, which takes advantage of wavelet multilevel decomposition, is used for derivative calculations. The prowess and computational efficiency of the method are demonstrated for the solution of a number of two-dimensional test problems.
SIAM Journal on Scientific Computing | 2005
Niciiolas K.-R. Kevlahan; Oleg V. Vasilyev
Two mathematical approaches are combined to calculate high Rey\-nolds number incompressible fluid-structure interaction: a wavelet method to dynamically adapt the computational grid to flow intermittency and obstacle motion, and Brinkman penalization to enforce solid boundaries of arbitrary complexity. We also implement a wavelet-based multilevel solver for the Poisson problem for the pressure at each time step. The method is applied to two-dimensional flow around fixed and moving cylinders for Reynolds numbers in the range
Physics of Fluids | 2004
Daniel E. Goldstein; Oleg V. Vasilyev
3\times 10^1 \le Re \le 10^5
Physics of Fluids | 2001
Youhei Morinishi; Oleg V. Vasilyev
. The compression ratios of up to 1000 are achieved. For the first time it is demonstrated in actual dynamic simulations that the compression scales like
Journal of Computational Physics | 2006
Jahrul M. Alam; Nicholas K.-R. Kevlahan; Oleg V. Vasilyev
Re^{1/2}
Physics of Fluids | 2002
Giuliano De Stefano; Oleg V. Vasilyev
over five orders of magnitude, while computational complexity scales like
Geophysical Research Letters | 1998
Oleg V. Vasilyev; Yuri Y. Podladchikov; David A. Yuen
Re
Journal of Computational Physics | 2003
Andreas Haselbacher; Oleg V. Vasilyev
. This represents a significant improvement over the classical complexity estimate of
International Journal of Computational Fluid Dynamics | 2009
Jonathan D. Regele; Oleg V. Vasilyev
Re^{9/4}