5610

5252

كارشناسي ارشد

مهندسي شيمي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مهندسي شيمي

1389

يازده،125ص.: مصور،جدول،نمودار

ص.ع.به فارسي و انگليسي

محسن نصر اصفهاني، مسعود حق شناس فرد

27/10/89

محمود اشرفي زاده، محمدرضا احساني

مهندسي شيمي

ID5252

به فارسي و انگليسي: قابل رويت در نسخ ديجيتالي

CFD Analysis of bubble motion in stagnant fluid and stirred tank Meysam Khodadadi me khodadadi@Gmail com 2010 08 2 Department of Chemical Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiDr M asresfahany mnasr@cc iut ac irDr M Haghshenas Fard haghshenas@cc iut ac irAbstractThe rise of bubbles in viscous liquids is not only a very common process in manyindustrial applications but also an important fundamental problem in fluid physics In thisstudy movement of single bubble in both stagnant and turbulent flow has been simulated The one fluid approach is likely to continue to remain an important strategy to handlemultifluid and multiphase problems In this approach the Navier Stokes equations allowfor arbitrary changes in the material properties of the fluids While the differential formdoes not allow discontinuous material properties numerical methods based on the finite volume method are equivalent to working with the integral form of the governingequations where no smoothness assumption is made The interface capturing PLIC VOFmethod that is based on one fluid approach is used to track the bubble interface The VOFapproach should be used when small scale processes occurring near an interface separatingthe fluid particle from the continuous phase play a crucial role Many commercial CFDcodes now include the option of simulating free surface or multiphase flows using theVOF method In the current dissertation this numerical algorithm is used to simulate 3Dbubbles rising in viscous liquids with large density and viscosity ratios representative ofthe common air water two phase flow system The results of present thesis are presentedin three sections First movement and deformation of single air bubble rising throughstagnant water has been simulated After comparing the results both qualitatively andquantitatively by experimental result that is present in literatures averaged error of 1 2 has been achieved in terminal velocity Second the flow field in baffled cylindrical tankstirred by a Rushton turbine impeller has been simulated Impeller rotation is simulated byboth the MRF and SG method The MRF method is one of the main approaches forapproximating unsteady flow in steady condition while in the SG approach full transientsimulations are carried out using the two grid zones By means of initializing the SG solverwith the converged results of MRF method the pseudo steady state condition achieved at4 5 impeller rotation Despite increasing the resolution in this model has no influence onprediction of averaged velocities but it leads to better prediction of turbulent kineticenergy k Finally Bubble movement and deformation in validated stirred tank issimulated in three impeller Reynolds numbers Shape oscillation and path transition ofbubbles show that surface tension force has important effect on bubble shape Key Words Bubble CFD Stirred tank Stagnant water Volume of Fluid VOF MRF Sliding Grid

محسن نصر اصفهاني، مسعود حق شناس فرد

محمود اشرفي زاده، محمدرضا احساني