6093

5702

كارشناسي ارشد

تبديل انرژي

اصفهان: دانشگاه صنعتي اصفهان، دانشكده مكانيك

1390

هفده،131ص.: مصور،نمودار

ص.ع.به فارسي و انگليسي

احمدرضا عظيميان

ابراهيم شيراني

3/5/90

احمد صابونچي، محمود اشرفي زاده

مهندسي مكانيك

ID5702

به فارسي وانگليسي: قابل رويت در نسخه ديجيتالي

Numerical Solution of Roughness Effect on Slip Flow Parameters in Micro Channel Mohammad Amin Hajibabaei amin hb64@gmail com 9th june 2011 Department Of Mechanical Engineering Isfahan University of Technology Isfahan 84156 83111t IranDegree M Sc Language FarsiSupervisor Ahmad Reza Azimian azimian@cc iut ac irAbstractIn the present work the effect of surface roughness on laminar fluid flow in micro channels has been studied According to value of the Knudsen number 0 1 Kn 0 01 continuum hypothesis is feasible and slipboundary condition is assumed The Navier Stokes equations are solved numerically with the finite elementmethod According to the flow Mach number Ma 0 3 and negligible temperature variation along theshort length of the channel incompressible fluid with constant density is assumed Air is the working fluidinside the channel Analytical and numerical results for velocity and poiseuille number of smooth channelhave been compared and the error was less than 1 wich is acceptable Roughness is modeled as a series ofalternating barriers with triangular base geometry on two dimensional channel walls The effect of roughnessheight variation from one to six percent of channel height is examined The roughness element bottom widthvariation from one to thirty times of roughness height is examined too Also the distance variation betweenroughness elements from zero to about eight times of roughness width is examined The roughness elementtop width variation from zero to a value equal to roughness bottom width is examined These effects werestudied on the slip and poiseuille number Also the effect of varying roughness geometry from twodimensional to three dimensional is studied Variation of width and height are done simultaneously and fortriangular elements In the other word for each height different widths are assumed Triangular elements withfixed height and fixed bottom width are used by varying the distance between the elements An element witha fixed bottom width and fixed Ra is used by variation of top width of the element Due to varying elementshape from triangular to trapezoidal and then to square and the necessity of constant Ra element heightvaries A triangle roughness element with constant height and width and zero distance between elements isextruded along the z direction to change the geometry from a two dimensional case to a three dimensionalcase So roughness is created perpendicular to the flow direction in the form of a strip An example of realsurface with this kind of roughness is introduced The results show that prediction of slip and poiseuillenumber would have almost 100 and 27 errors respectively with variations of roughness parameters in acertain knudsen number The result of all channels are studied and compared in the locally developed part ofthe flow For a number of studied channels the Poiseuille number of developed parts have been compared

احمدرضا عظيميان

ابراهيم شيراني

احمد صابونچي، محمود اشرفي زاده