Extended synthetic eddy method to generate inflow data for turbulent thermal boundary layer

Abstract

We propose an extended synthetic eddy method (XSEM) based on the synthetic eddy method, which includes the temperature fluctuation component in the turbulent flux tensors, to generate time-dependent turbulent thermal inflow data for a spatially-developing boundary layer. The proposed XSEM is applied to large eddy simulations of a spatially-developing turbulent thermal boundary layer on a flat plate with an isothermal wall condition. Time-varying turbulent thermal inflow fields are reconstructed by composing the prescribed mean and reproduced fluctuations fields, along with Cholesky decomposition to the turbulent flux tensor with thermal flux. The obtained results indicate that the inflow generated by the proposed XSEM provides self-sustaining turbulence with fully recovered turbulent statistics behind a re-developing boundary layer region with the recovery distance roughly seven times of the inlet boundary layer thickness. Finally, we demonstrate the robustness of the XSEM for providing appropriate inflow data for simulations of turbulent thermal boundary layer flows for different Prandtl numbers.