A Universal Wall-Modeling Approach for Large-Eddy Simulations of Complex Turbulent Flows with Heat Transfer

Since last few decades, the Large-Eddy Simulation (LES) technique has been widely adapted from academic research to industrial practice with anticipation of LES to be accurate and reliable to predict the unsteady turbulent heat and fluid flows. However, in LES, fine numerical grids scaled by viscous length are indispensable to resolve the turbulent motions in the near-wall dominant flows, which makes LES of wall bounded flow very computational expensive and time-consuming. This shortcoming has limited and impeded the application of LES to realistic industrial flows with solid walls. To circumvent this problem, a widely applied method is to model the flow in the near-wall region, which is expected to provide the essential quantities accurately, e.g. the turbulent quantities in the outer layer, the frictional velocity and the heat flux in an energy system, with significantly reduced computational costs. Despite numerous available wall modeled LES (WMLES) approaches, they are rarely capable to predict the complex heat and fluid flows in a realistic industrial flow application, which is characterized as highly unsteady non-equilibrium wall bounded turbulent flow. The present work focuses on the development of a reliable and efficient universal wall-stress model for LES that allows to predict unsteady non-equilibrium wall bounded turbulent flows with conjugate heat transfer in industrial flow applications. It is progressively accomplished in four major steps: (1) the development of novel non-equilibrium wall functions for velocity and temperature in the context of turbulent and heated fluid flow; (2) implementation of the novel non-equilibrium wall functions into the framework of OpenFOAM by also taking into consideration of the conjugate heat transfer problem in the context of incompressible heat and fluid flow with constant and variable physical properties for LES; (3) verification and validation of the proposed WFLES approach by means of several generic benchmark test cases relevant to exhaust gas after-treatment ...