Three-dimensional Simulations Of Marangoni Effect Induced By Mass Transfer

The Marangoni effect induced by mass transfer in two-dimensional and three-dimensional models was compared by the numerical simulation.The instability of Marangoni effect in the plat interface and spherical interface was studied respectively by the three-dimensional numerical simulation.Firstly,Marangoni effect induced by mass transfer process in the acetone-toluene-water droplet was studied,and results of two-dimensional and three-dimensional models were compared.Comparing with experimental results,it showed that the Marangoni effect is a phenomenon occurred in a three-dimensional space.It is not reasonable to simplify this three-dimensional phenomenon to a two-dimensional phenomenon.For liquid droplets with different initial acetone concentration,the higher initial concentration was corresponding to the shorter critical time of the Marangoni convection induced and the stronger intensity of the Marangoni effect.For evolution of the Marangoni convection in the mass transfer process,it can be divided into four stages:initial,trigging,stable and decaying stage.Secondly,instability of the Marangoni effect in the three-dimensional plat interface was studied,and the influence of the perturbation on the Marangoni effect during mass transfer process was investigated.The perturbation mode had no effect on the initial mass transfer rate,but it was closely related to the concentration field of the initial Marangoni convection.The interfacial average concentration,interface average velocity and standard deviation of the interface average concentration tended to be consistent regardless of the perturbation mode finally.It also showed that the perturbation influenced the shape and evolution of the initial Marangoni convection.The perturbation promoted the occurrence of the Marangoni convection,but it had no effect on the final concentration field.At the same time,the influence of the wave number in the double period perturbation was investigated.The larger the wave number was,the smaller the critical time value of Marangoni convection was,and the smaller the maximum velocity was.Finally,instability of the Marangoni effect in the three-dimensional sphere interface was studied.The perturbation affected the shape and evolution of the initial Marangoni convection,and promoted the occurrence of the Marangoni convection,but had no effect on the final concentration field for both the flat interface and the sphere interface.The difference between the spherical interface and flat interface was that the spherical interface did not appear the concentration field corresponding to the period perturbation.Therefore,it cannot develop into a paired cell structure with the period perturbation.Due to the curved interface,diffusion were through the spherical interface even if a stable concentration field existed,it cannot maintain a stable structure of the concentration field.Therefore,the influence of interface shape on the Marangoni effect cannot be neglected.For the Marangoni effect in the deformable interface,the influence of the interface shape on the Marangoni effect must be taken into account.