The internal circulations on internal mass transfer rate of a single drop in nonlinear uniaxial extensional flow

Abstract

The internal flow of a droplet in the nonlinear extensional flow field will exhibit more than two internal circulations with the variation of nonlinear intensity (E). In this paper, the effect of positions and sizes of internal circulations on internal mass transfer rate of a single spherical droplet in a nonlinear extensional flow field is studied and compared with that in a linear extensional flow field. The simulation results show that when E ≥ 0, there are two symmetrical internal circulations in the droplet, which is the same with that in a linear extensional flow. The limit value of mass transfer rate Sh is 15, which is equal to that in a linear extensional flow, no matter how large E is. When E ≤ –3/7, the number of internal flow circulation of a droplet increase to four and the transfer rate Sh increases. When E = –1, the maximum internal transfer rate Sh equals 30 which is twice of that in a linear extensional flow. The generation of new flow circulations in droplets and the circulation positions will enhance mass transfer when E ≤ –3/7, which provides a new idea for enhancing the internal mass transfer rate of droplets.