On the Modeling of Dissipation Anisotropy, Pressure Diffusion and Coherent Structures in Stratified Wakes Using Second Moment Closure*

Simulation of wake flows encountered in the environment, which are often characterized by high Reynolds and Froude numbers, requires considerable computational resources, prohibiting the use of DNS/LES. Second-Moment Closure (SMC) is suitable for such complex flows. Recent DNS studies by the authors have highlighted important inconsistencies/errors in conventional SMC^1,2,3. Specifically, we have identified the lack of suitable dissipation anisotropy and pressure diffusion modeling as critical shortcomings in these 11-equation models. This presentation summarizes our recent work to develop and validate models for these important Reynolds stress and density flux transport mechanisms. To this end, we use DNS, physical reasoning, and machine learning tools.

[1] Jain, Naman, et al. "Insights into second-moment closure modelling performance for stratified wakes from DNS ensembles." Bulletin of the American Physical Society 66 (2021)

[2] Jain, Naman, et al. "Second Moment Closure Modeling and Direct Numerical Simulation of Stratified Shear Layers." Journal of Fluids Engineering

[3] Jain, Naman, et al. "A Study of Second Moment Closure Modeling for Stratified Wakes Using DNS Ensembles." Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2022