4668

4396

كارشناسي ارشد

مهندسي مكانيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1387

نه،90،[II]ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

احمدرضا پيشه ور، ابراهيم شيراني

احمدرضا پيشه ور، ابراهيم شيراني

88/7/13

احمدرضا سعيديان، سعيد مرتضوي

مهندسي مكانيك

ID4396

به فارسي و انگليسي: قابل رويت در نسخه ديجيتالي

Numerical Modeling of Interfacial Flows Based on Level Set Method and Comparing with VOF Method Ali Nematbakhsh nematbakhsh@me iut ac ir February 9 2008 Department of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisor s Names And Email addresses Ahmad Reza Pishevar Ebrahim Shiraniapishe@cc iut ac ir eshirani@cc iut ac irAbstractInterfacial flows include lots of problems in fluid mechanics such as Oil industry design ofBoilers and reactors Regarding to importance of these kinds of flows two well knowneulerian methods named Volume of Fluid and Level Set are compared with each othercompletely In order to judge against these two methods motionless droplet and rising bubbleare numerically modeled with the assistant of these two methods and the results are verifiedwith available experimental data By considering discretizing method studying theconservation of mass and ability to model the curvature of the interface we came to thisconclusion that Level set method can calculate the curvature of the interface with greataccuracy On the other hand Level set method can not satisfy the mass conservation with greataccuracy The reason for this problem is that Level set equation is not based on conservationof physical properties Volume of Fluid method is based on volume conservation in each fluid therefore the mass ispreserved in each phase of incompressible flows with great accuracy On the other hand as aresult of using discrete function for modeling the interface curvature can not be calculatedwith fine precision in this method Because of the accuracy in calculating the curvature of the interface and acceptable massconservation in the time steps that we need for modeling our problems Level set is used formodeling Problems such as falling droplet rising bubble coalescence of two Bubble and alsodroplet impact on a solid surface At first falling droplet is studied for different Weber numbers and values for Weber numberis found which for them bifurcation of the droplet occur By changing the rectangular coordinates in to polar coordinates rising of three dimensionalaxisymmetric bubbles is studied The reasons for the deformation of the bubbles are discussedtheoretically Comparing the numerical results with available experimental data reveals theaccuracy of the method In addition the coalescence of two bubbles which is complicatedphenomena in multiphase flows is numerically modeled and the results are verified byexperimental data At last by adding contact angle model to the level set code changing the frequency ofapplying reinitialization equation and increasing the number of fictitious time inreinitialization equation droplet impact on solid surface is modeled numerically The secondphase of flow which is air here is also considered All steps of droplet impact such asadvancing and recoiling are numerically captured The main advantage of our simulationcompare with previous ones is that the Level set function is not change near the contact pointof solid liquid and gas Finally the recoiling velocity is calculated for different initialvelocities and theoretical discussion is done for the reasons of these different recoilingvelocities Key Words Two phase flows Surface tension Level set VOF

احمدرضا پيشه ور، ابراهيم شيراني

احمدرضا پيشه ور، ابراهيم شيراني

احمدرضا سعيديان، سعيد مرتضوي