Interaction between the turbulent boundary layer flow of superheated vapor and the velocity field induced by liquid vaporization

We consider the heat and mass transfer in the turbulent boundary layer flow over a stationary but evaporating liquid surface via direct numerical simulations. We investigate the influence of the vaporization of a static liquid pool at its saturation temperature on a fully developed turbulent boundary layer of superheated vapor, where the vaporization mass flux is treated as a boundary condition for the wall-normal velocity. It is found that the vaporization enhances the boundary layer growth whilst the friction coefficient and the Stanton number are reduced. Turbulent production is shifted further away from the wall and increased in the logarithmic layer whereas the near-wall dissipation rate is decreased in the viscous sub-layer due to the presence of non-vanishing velocity fluctuations. Spectral analysis showed an associated increase in the cross velocity energy spectrum due to vaporization as well as a shift of the peaks towards smaller wavelengths. A similar behavior is observed for the wall-normal turbulent heat flux spectra. The streamwise velocity energy spectrum decreases in the viscous sub-layer and increases in the logarithmic layer.