شبيه سازي عددي حركت قطرات در جريان روي سطح شيب دار

چكيده انگليسي :

Numerical simulation of motion of drops on an inclined channel Mahdi Mashhadi Tafreshi M Mashhaditafreshi@me iut ac ir Date of Submission 2011 02 29 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor Saeed Mortazavi Saeedm@cc iut ac irAbstractThe flow of two dimensional drops suspended in an inclined channel is studied by numerical simulations atnon zero Reynolds numbers The flow is driven by the acceleration due to gravity and there is no pressuregradient in the flow direction The equilibrium position of a drop is studied as a function of the Reynoldsnumber the Capillary number the inclination angle and the density ratio It is found that the drop alwayslags the undisturbed flow More deformable drops reach a steady state equilibrium position that is fartheraway from the channel floor For drops that are heavier than ambient fluid the equilibrium position movesaway from the channel floor as the Reynolds number is raised The same trend is observed when theinclination angle with respect to horizontal direction increases When the inclination angle of the channelwith respect to horizontal direction increases the equilibrium position of a heavier drop moves away fromthe channel floor Result is in agreement with computational modeling of Campbell and brennen on chuteflow of granular materials For neutrally buoyant drops the equilibrium position weakly changes withinclination angle For drops that are lighter than the ambient fluid the equilibrium position moves towardsthe channel floor as the inclination angle increases The behavior agrees with computational modeling ofchute flow of granular materials A drop that is lighter than the ambient fluid reaches a steady stateequilibrium position closer to the channel floor when the Reynolds number or inclination angle increases The lateral equilibrium position of drop depends on the drop deformation The equilibrium position movesaway from the channel floor as the Capillary number or drop deformation increases The result is consistentwith experimental findings of Karnis et al and numerical simulations of Zhou Pozrikidis at zero Reynoldsnumbers Simulations of 40 drops in a relatively large channel show that drops move away from thechannel floor when the density ratio is larger than unity The behavior is similar to that observed in granularflows The effect of the Reynolds number the Capillary number and density ratio on the distribution ofdrops and the fluctuation energy across the channel are investigated It is found that drops tend to stay awayfrom the channel floor which is consistent with the behavior observed in granular flow regime Drops try tostay away from the channel floor in the simulations performed here The maximum concentration appears atsome distance away from the floor which depends on the effective parameters of the flow Drops that areless deformable will further stay away from the channel floor Also drop appear at a larger distance fromthe floor as the Reynolds number increases Simulations at large density ratios show that results are morecompatible with computer simulations of granular flows The behavior observed here resembles more togranular flow regime when the restitution coefficient is low Simulation performed here by solving theNavier stokes equations agree with computational modeling of granular flows under some specificrestriction Specifically granular flow simulations are more compatible with current results with lowrestitution coefficients Keywords Reynolds number Capillary number Density ratio Inclination angle Bondnumber Equilibrium position Fluctuation energy Density drop distribution

مشهدي تفرشي، مهدي

شبيه سازي عددي حركت قطرات در جريان روي سطح شيب دار

مكان تعادل , عدد رينولدز , جريان پواسل , نسبيت چگالي , عدد كپيلاري