Implementation of Integral wall model for LES in an unstructured-grid finite-volume flow solver and its application to non-equilibrium turbulent boundary layer.

Integral wall model (IWM) for LES developed by Yang et al. (Phys. Fluids 27, 025112 (2015)) has been shown to incorporate more near-wall physics than equilibrium wall model (EQWM) while being algebraic. However, widespread adoption of IWM warrants two key extensions to the original study. First, while IWM has been used largely in structured-grid framework to date, implementation in flow solvers that can handle complex geometries and unstructured grids is lacking, restricting the model’s potential for practical problems. Second, the model needs to be evaluated in flows with strong nonequilibrium effects. In this talk, we first discuss challenges unique to IWM’s implementation in the unstructured-grid framework associated with data exchange and wall-tangential gradient calculations. Cost of wall modeling will be discussed in comparison to EQWM. For assessment in nonequilibrium flow, we consider two experiments at moderately high Re_θ (~3000-7000): a TBL successively subjected to varying pressure gradient (ZPG, FPG and APG) zones (J. Fluid Mech. (2020), vol. 897, A2.), and a spatially developing 3DTBL subjected to a 30^o bend (J. Fluid Mech. (1994), vol. 212, pp. 183-209). Mean flow statistics, boundary layer integral quantities and wall stress predictions from WMLES will be analyzed.