Numerical Simulation of Flat Plate Boundary Layer Transition with Synthetic Inlet Turbulence

A large-eddy simulation (LES) of a flat plate boundary layer undergoing transition to turbulence, i.e., ERCOFTAC’s test case T3B, is performed with synthetic inlet turbulent fluctuations. Generated by Billson and Davidson’s method, the isotropic and homogeneous synthetic turbulence is imposed on a uniform flow directly at the inlet of the computational domain without a precursor adaptation region. The issue of the maximum-contained number (MCN) is specified, which aims at the determination of mesh distribution to maintain and strengthen the correlation between neighboring cells. The numerical results are realistic under the original synthetic turbulence if the MCN is suitably set. For further improvement of the prediction, a correction based on the Poisson equation is adopted to make the synthetic turbulence divergence-free, which is the basic requirement of incompressible flow. It is shown that with the divergence correction, the simulation results are better, and in particular, the decay of free stream turbulence near the upper boundary is more reasonable.