Constrained large-eddy simulation of laminar-turbulent transition in channel flow

A constrained large-eddy simulation (CLES) of a laminar-turbulent transition in a temporally developing channel flow is performed. First, we confirm the capability of CLES to simulate this transition problem using the a priori Reynolds stress estimated from a direct numerical simulation. Based on the analysis of the Reynolds stress during the transition process, an intermittency factor is introduced in the Reynolds-averaged Navier-Stokes equation (RANS) model to account for the transition property. Two simple approaches are used to construct the intermittency factor. One is based on the shape factor, and the other is based on the coefficients of Smagorinsky models. The CLES results using the intermittency modified RANS model can accurately predict the onset of the transition and the basic transition process, in a manner similar to a large eddy simulation with dynamics Smagorinsky model (LES-DSM). Meanwhile, CLES preserves its advantage over LES-DSM in the turbulent state. The present work illustrates that CLES can be used to simulate transitional flows. (C) 2014 AIP Publishing LLC.