Convective heat transfer in the near-wall turbulent gas stratum

Abstract

In order to diminish the computational cost of heat transfer simulations, some wall functions had been often introduced in numerical algorithms. More universal and robust dimensionless velocity functions that can be employed both in buffer and equilibrium parts of the near-wall turbulent gas stratum are offered here for consideration. They have been obtained on the basis of Prandtl’s semiempirical hypothesis of turbulence. A mode, how to determine the one-sided derivatives of the gas velocity and temperature at the wall surface on a coarse grid, has been substantiated. That allows applying the boundary conditions of Neumann and Robin type for differential equations of the convective heat transfer to the confining walls from the turbulent gas flow. A semiempirical formula for the eddy viscosity in the wall proximity has been deduced, and a valid boundary value has been determined also for the rate of turbulence-energy dissipation. It is demonstrated that the simulation results coincide sufficiently with experimental data.