Application of the turbulent potential model to transition and large eddy simulation.

摘要

The turbulent potential model is a non-equilibrium RANS model with the predictive capabilities of a Reynolds stress transportation model but the cost and complexity of more popular two equation models. It has been applied to numerous fully turbulent flows with great success. In this work, the model is applied to two new regimes, namely the transitional flow, and subgrid flow motion in Large Eddy Simulation (LES). For the transitional flow, the model is used in a universal CFD code to predict both the natural transition and bypass transition of flat plate boundary layers. The effects of acoustic noise and pressure gradients on transition are studied. The model is also demonstrated on its ability to predict relaminarization in channel flow. The evolution of flow variables over a wide range of the transition process is successfully captured.; For the LES, the model is used to compute the subgrid scale turbulence for an isotropic decaying turbulent flow. An exact projection method with second order temporal accuracy and rigorous conservation properties is developed to solve for the larger scales. The result is close to DNS simulation data. Theoretical studies of this new approach to LES are performed. Analysis of the results shows that the turbulent potential model can be used to construct a universal model which transits automatically from RANS model to LES.