‎محسن دوازده امامي، احمد سوهانكار اصفهاني

1396/10/04

كتابنامه

مكانيك

مهندسي مكانيك

ID9630

به فارسي و انگليسي

9Investigation of particle size segregation in poisseuile flow in two dimensions exclusive of gravity force Mohammad Abdolmaleki Mohammad abdolmaleki@me iut ac ir Date of Submission 2015 10 06 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Saeed Mortazavi s mortazavi@cc iut ac irAbstract The motion of drops suspended in another fluid has a wide variety of practical applications Theseinclude the flow of oil and water through pipelines the recovery of oil through porous rock the flow ofslurries and polymer processing The lateral migration of deformable particles in Poisseuile flow has beensubject of many investigations The lateral migrations of immersed objects in carrier fluids are veryimportant in transport processes where mass momentum and energy are exchanged The lateral migration of a drop in Poisseuile flow is studied numerically in two dimensions Themechanism of lateral migration for one drop was explained by Feng et al The wall repulsion force whichis known as a lubrication effect drives the drop to the channel centerline A Magnus type lift force acts onthe drop which depends on drop rotation and drop slip velocity The direction of this lift depends onwhether the drop leads or lags the flow The curvature of velocity profile also imposes a lateral force thatalways drives the drop to the channel walls Besides the inertia of flow develops a lateral force which isknown as inertia lift Saffman lift that depends on the direction of the slip velocity The equilibriumposition of a drop is a result of balance between aforementioned forces In this research the lateral migration of two dimensional drops with two different sizes in Poiseuille flowat finite Reynolds numbers are studied numerically under conditions of negligible gravitational force Thefull Navier Stokes equations are solved by a finite difference front tracking method that allows a fullydeformable interface between the drop and the suspending medium The effect of dimensionlessparameters on the effective viscosity the fluctuation energy across the channel and particle sizesegregation are investigated Simulations were performed at a unity density and viscosity ratio with aconstant areal fraction 0 2 The number of drops considered were 24 48 and 51 that were suspendedinside a periodic channel using two different initial configurations Results show that the average densitydistribution of drops across the channel are independent of the initial configuration The densitydistribution of large and small drops are different Therefore a particle size segregation is observed Thereis a tendency for large drops to migrate to the center of the channel whereas small drops migrate towardsthe channel walls The effect weakens as the Reynolds number increases and Capillary number decreases Drops segregation also weakens when drop sizes get close 51 drops The strongest segregation occurswhen the difference between drop sizes is largest 24 drops Keywords Poisseuile flow Effective viscosity Particle size segregation Density distribution Differentsizes

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‎محسن دوازده امامي، احمد سوهانكار اصفهاني