شبيه سازي عددي دوبعدي قطرات معلق در جريان برشي ساده در اعداد رينولدز غير صفر

چكيده انگليسي :

70Numerical Simulation of Drops Suspended in Simple Shear Flow at Nonzero Reynolds Number Reza Khazaeli r khazaeli@me iut ac ir Date of Submission 3 3 2012 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiSupervisor S Mortazavi saeedm@cc iut ac irAbstractThe flow of suspensions through channels and tubes has been the subject of many investigations The flowof slurries the recovery of oil the transport of oil and water through pipelines and food and materialprocessing are typical application of these flows Since the distribution of drops through of the channeldetermines the flow rate lateral migration of drops and their final equilibrium position is of particularinterest Suspensions of two dimensional drops in simple shear flow are studied at nonzero Reynoldsnumbers by numerical simulations The flow is studied as a function of the Reynolds number the Capillarynumber and the drop sizes Results are obtained using a finite diffrence front tracking method in a periodicdomain Suspension of drops at a moderate areal fraction 0 44 is studied by simulations of 36 144 and288 drops It is found that the effective viscosity decreases with Capillary number and the normal stressdifference increases The results for the normal stress difference show oscillations around a mean value atsmall Reynolds numbers and it slightly increases as the Reynolds number is raised It is also found thatsimilar to flows of granular materials suspension of drops at finite Reynolds numbers shows the same trendfor the density and fluctuation energy distribution across the channel Similar to the motion of a single drop drops migrate away from the walls It is found that the size of the clusters decreases with Capillary numberand Reynolds number Other achievements are that an decrease in the size of the drops leads to a reductionin the size of the clusters and that for highly deformable drops almost no cluster forms These phenomenais due to the more freedom of the drops while displacement It was observed that the diagrams of theeffective viscosity and normal stress difference pertained to the small sized drops include less oscillationscompared with the large sized drops which can be related to the reduction in the size of the clusters Examining the diagrams of the density it was inferred that the transverse immigration of the drops towardthe center of the channel increases with an increase in the capillary number Also the diagrams associatedwith the fluctuation energy suggest that this quantity increases with an increase in the value of the Reynoldsnumber The reason must be sought on one hand in the decrease in the size of the clusters and on the otherhand in the increase in the number of collisions Furthermore it was reported that while the deformabilityof the drops enhances the reduction in the number of collision between the drops causes a decrease in thevalue of the fluctuation energy Also the fluctuation energy of the flow is found to firstly approach higherlevels with an increase in the number of the drops and then reach a limit value This may be attributed tothe increase in the number of the collisionsKeywords Two phase flow Front Tracking Drop Shear flow

خزائيلي، رضا

شبيه سازي عددي دوبعدي قطرات معلق در جريان برشي ساده در اعداد رينولدز غير صفر

جريان دوفازي , رديابي سطح مشترك , عدد كپيلاري