Turbulent Flow, Heat Transfer, and Mass Transfer in a Tube With Surface Suction

Abstract

The problem of turbulent pipe flow with mass removal at the bounding surface is analyzed, and numerical results are presented for the friction factor, axial pressure gradient, heat and mass transfer coefficients, and velocity and temperature profiles. The results, which are relevant to forced-convection condensation in a tube (either with or without noncondensable gases) are shown to be substantially affected by even small amounts of wall suction. Therefore, the present findings do not support the current practice of using impermeable-boundary transfer coefficients in condensation calculations. The analysis is performed under the condition that the velocity field is locally self-similar. Corresponding conditions are used for the distributions of temperature and mass fraction. The cross-sectional distributions of the transverse velocity and the shear stress are not constrained in advance, but rather, are permitted to vary in accordance with the conservation laws. The turbulent transport is expressed in terms of the mixing-length, model, modified in the neighborhood of the wall by a specially derived dumping factor.