4902

4605

كارشناسي ارشد

آب

اصفهان: دانشگاه صنعتي اصفهان، دانشكده عمران

1388

[يازده]، 129 ص:جدول، نمودار

ص.ع. به: فارسي و انگليسي

محمدرضاچمني

كيوان اصغري

16/10/88

محمد هادي افشار، محمدكريم بيرامي

مهندسي عمران

ID4605

به فارسي و انگليسي: قابل رويت در نسخه ديجيتال

Interpolation Schemes in the Method of Characteristics for Water Hammer Problems with Complex Boundary Conditions Zahra Mohammadian z mohammadian@yahoo com Spring 2009 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors Dr M R Chamani mchamani@cc iut ac irAdvisor Dr K Asghari kasghari@cc iut ac irAbstract In this research different interpolation schemes in the method of characteristics MOC were used forwater hammer problems Governing equations of water hammer were solved using the complete andapproximate method of characteristics considering complex boundary conditions Since the analysis ofwater hammer problems requires interpolation some different interpolation methods were applied Inaddition to interpolation schemes used in the literatures cubic hermite nonlinear interpolation was usedfor the first time After discritization of governing equations and computer programming severalmodels were selected for validation In some models numerical results were compared withexperimental results In addition the effects of courant number on the results are investigated Both linear and nonlinear interpolation schemes show that the difference between results of usingcomplete or approximate equations are small and can be ignored In all schemes approximateequations needs less CPU time to process It is shown that space and time line interpolation in linearand nonlinear methods achieved better solution compared to hybrid interpolations By decreasing theCourant number nonlinear interpolation schemes lead to more accurate results than the linear ones andamong nonlinear methods hermite method shows fewer numerical errors in comparison with splinemethod The comparison indicates that nonlinear methods have less phase difference with measuredresults and in nonlinear methods hermite scheme results are closer to experimental results Decreasingthe courant number decays the accuracy of results especially in linear methods Space lineinterpolations are less sensitive to the variation of courant number than time line ones The results of different models show that for the complex boundary conditions used in this work thechoice of interpolation scheme is not crucial and linear interpolations are recommended because ofless computational costs Energy approach is also used to compare numerical errors of differentinterpolation Schemes which show less error in nonlinear methods especially in the hermite scheme Altogether comparison of accuracy of different interpolation schemes shows that time lineinterpolations are the best method however these schemes require more time and computer capacity incomparison with space line schemes In the models investigated in this work cubic hermite schemereveals the most accurate solution Key Words Water Hammer Complex Boundary Conditions Method ofCharacteristics MOC Nonlinear Interpolation Hermite Scheme

محمدرضاچمني

كيوان اصغري

محمد هادي افشار، محمدكريم بيرامي