Proposal for wall function for friction and heat transfer in the presence of roughness and mass transfer

The heat transfer characteristics of a turbulent boundary layer over a rough, porous wall through which mass is injected are predicted. A wall function that accounts for the simultaneous influences of roughness and mass transfer is proposed. Although it has no strong theoretical foundation, the proposal agrees with experiment. Cases with and without unheated lengths of plate are considered. The separate effect of roughness without mass transfer is investigated. The predictions compare well with the measurements for uniform-grain elements under fully rough conditions.