Numerical Simulation Of Marangoni Convection In Porous Media

The Marangoni convection instability induced by interface mass transfer in the porous media was studied by the numerical simulation method.At the same time,effects of multiple factors on the artificially induced Marangoni convection in the porous media model were studied.The Marangoni convection instability caused by interface mass transfer was studied by dimensionless analysis.The influence of multiple parameters such as the interface disturbance,Rayleigh convection and porous media structure on the Marangoni convection was investigated.Different from the pure nonporous fluid model,the interface disturbance in the porous model had little effect on the Marangoni convection.Under different disturbance intensities,the final stable interfacial average velocity,concentration and standard deviation of the interface concentration tended to be consistent.At the very beginning of the initiation stage of the Marangoni convection,the bigger disturbance intensity caused the critical time of the Marangoni convection to be slightly advanced.The Rayleigh convection could inhibit the development of Marangoni convection,but only at a large number of Rae it could have a small impact on the interface parameters.The Rayleigh convection occurs in the bulk liquid phase,so its ability to drive the liquid bull is stronger than the Marangoni convection though it has little influence on the interfacial liquid movement.For porous media structures,the smaller the porosity and permeability,the weaker the Marangoni convection strength.However,the presence of the porous media tended to moderate the Marangoni convection initiation process on comparison with to the pure nonporous fluid model.Meanwhile,the influence of variation of mass transfer conditions on the Marangoni convection was investigated.Different from directly increasing convection driving force,the Marangoni convection maintained high intensity throughout the initiation stage.Variation of mass transfer conditions maked the Marangoni convection intensity stronger and attenuation faster.For artificially provoked Marangoni convection by means of addition of isopropanol on the interface center area,the Marangoni convection cannot effectively diffuse into the liquid bulk of the porous medium model although the Marangoni convection driving force was large.The influence of the different isopropanol concentration at the interface on the Marangoni convection was investigated.Studies showed that decrease of the interface concentration gradient maked the average velocity of the interface smaller,and the convection attenuated slower.When the interface concentration gradient was less than a certain value,the amount of isopropanol entering the liquid phase was increased.The initial dosage variation of isopropanol by changing the thickness of the initial liquid layer containing isopropanol had little effect on the calculation results,and the interface parameters did not change much.However,if the method of changing the concentration gradient function was utilized to control the total amount of initial isopropanol,results showed that the increase of the total amount of initial isopropanol caused the interfacial convection velocity to slow down and the bulk velocity in the liquid phase to become faster.In addition,the presence of the gas-liquid mass transfer on the upper interface had little effect on the artificially induced Marangoni convection in the porous model.