1003 Direct Numerical Simulation of the Effects of Grid-Generated Turbulence on Turbulence Structure and Heat Transfer in the Turbulent Boundary Layer(1)

Abstract

The effects of external grid turbulence in a free stream on the turbulent boundary layer are investigated by means of the direct numerical simulation (DNS). A square turbulence-generating-grid, on which the velocity and components are set to zero, is located at a short distance downstream of the front edge of the flat boundary with a nonslip condition. The fractional step method is used to solve the governing equations. The results show that turbulence intensities, Reynolds stress, and heat flux normalized by the inner parameters are suppressed in the log-law region by the external grid turbulence.