Unsteady mass transfer in single drop systems with interfacial mobility

The simulation of unsteady conjugate mass transfer between a spherical droplet and the surrounding continuous fluid is based on the solution of the balance equations for momentum and mass in both phases. To reduce the effort required various approximations have been introduced. Some authors, for instance, compute the mass transfer in both phases seperately and add the resulting transfer resistances to estimate the rate of the whole process. The reliability of this procedure is discussed in the paper. Even in the case of a simulation of the conjugated problem differences between simulations and experiments are obvious. The neglection of instabilities in the phase interface by the model is supposed to be a reason for that. The influence of the Peclet number on the Sherwood number for a given Schmidt number is discussed. An upper and an lower limit of Pe can be found where further changes of that value have no influence on the mass transfer.