Interphase Mass Transfer Between A Single Particle And Extensional Creeping Flow

The fundamental research on transport phenomena(momentum,heat and mass transfer)of a single particle is of great importance in practical application in chemical and process industry.Droplets would deform gradually from prolate to ‘peanut’ shape in uniaxial extensional flow,or from oblate to ‘red-blood-cell’ shape in biaxial extensional flow.The wall effect between a stationary deformed drop and the modest extensional flow in a cross-intersected channel and the nonlinear flow that exists in industrial rotary devices is very common and plays an important role on particle transport phenomena.Unfortunately,most previous works are dedicated to studying a single spherical particle(bubble,liquid drop,or solid particle)immersed in a simplified linear flow,such as in simple shear flow or in simple extensional flow.In order to explore the complex problems precisely,this work studied numerically(by boundary element method,concentration transformation method)the internal,external,conjugate mass/heat transfer of a spherical/deformable particle immersed in simple/modest/nonlinear extensional creeping flows.For mass transfer from/to a single prolate droplet in simple extensional creeping flow,the effects of Peclet number(1≤Pe≤1000),capillary number(0≤Ca≤0.1),viscosity ratio(0.01≤λ≤ 1),diffusivity ratio(0.1≤K≤10)and distribution coefficient(0.1≤m≤ 10)on interphase mass transfer processes were examined in terms of numerical simulation.Given Pe,Ca,λ,K and m,an empirical correlation with an average relative deviation of 12% was proposed to predict Sherwood number Sh of prolate and spherical droplets suspended in uniaxial extensional creeping flow.For mass transfer from/to a single deformable droplet in the uniaxial and biaxial extensional creeping flow,the empirical correlations were proposed to predict the internal mass transfer rate of a deformable droplet(by adding parameter Ca to represent the deformation of a droplet)in simple extensional flow.For the unsteady conjugate interphase mass transfer between a stationary deformed drop and the modest extensional flow in a cross-intersected channel,the simulation results show that the mass transfer rate,analyzed and characterized by concentration variation and Sherwood number Sh,is affected by Ca,Pe,λ,K,m and wall proximity parameter W.For a single liquid drop immersed in a nonlinear extensional creeping flow,the empirical correlations of external mass transfer rate of a single spherical droplet in the nonlinear extensional flow were proposed to predict Sh in the range of 1≤Pe≤1000and-5≤E≤10.For that of a spherical solid in the non-linear flow,the empirical correlations of the external mass transfer of a single solid sphere were proposed to predict Sh in the whole range of 1≤Pe≤100000 and-5≤E≤10.