Unsteady heat and/or mass transfer from a fluid sphere in creeping flow

The transient heat and/or mass transfer from a fluid sphere with internal circulation into a flowing fluid are investigated. The temperature and/or concentration inside the sphere are considered uniform. Two cases are studied: the physical mass and/or heat transfer and the mass transfer accompanied by an isothermal, first-order irreversible chemical reaction in the continuous phase. Steady, creeping flow is assumed around and inside the sphere. The problem is solved by a finite difference method in the range of parameters, 10⩽Pe⩽1000, 0.01⩽H (Φh)⩽100, 0.1⩽Da⩽1000. The influence of distribution coefficient (H) or volume heat capacity ratio (Φh) on the transfer rate and thermal wake phenomenon is analysed.