مدل سازي عددي استهلاك انرژي موج به وسيله صفحه ي مشبك

چكيده انگليسي :

Numerical Modeling of Wave Energy Dissipation by Perforated Screens Majid Dorri m dorri@cv iut ac ir July 18th 2011 Department of Civil Engineering Isfahan University of Technology Isfahan 84156 83111 IranDegree M Sc Language FarsiSupervisors M Chamani Assosiate Prof mchamani@cc iut ac ir K Asghari Assistant Prof kasghari@cc iut ac ir AbstractIn this thesis Smoothed Particle Hydrodynamics SPH method is used for modeling dissipation of waveenergy with horizontal perforated plate placed under water surface in a towing tank Previous research usingtwo dimensional linear potential theory and Darcy s law is improved with Navier Stokes equation Thedeveloped SPH formulation applied to dam break and wave maker problems in order to validate theformulation Validation was achieved through comparison of numerical and experimental results existed inthe literature A new particle neighbor search is also developed and used for reduction of simulation time andthe computational cost of model Furthermore parallel processing is used for decreasing time of simulation The proposed algorithm is faster than other algorithms in the literature If shared memory parallelism SMP with increased in CPU is used for parallelism of calculations the time efficacy of simulation enhancedsignificantly With the use of parallel processing and new particle neighbor search the simulation timedecreases up to 10 times compared with the Linked Cell List LCL algorithm reported in the literature Thereduction of computational cost of modeling was important aspect in this research in order to be able toreduce the particle size or in another word increase the number of particles As a result the model wascapable of handling up to one hundred thousand particles small enough to pass the hole of perforated plate The simulation of dam break wave maker and wave reflection from a vertical wall are used to verify theparallel processed two dimensional codes written in C language Variation of wave front position withrespect to time shows a good agreement with laboratory data reported in the literature and indicates well behavioral characteristics compared to experimental data of Shao and Lo 2003 Simulation of piston wavemaker shows that the wave maker introduces regular wave perfectly which is the indication of stability andaccuracy of SPH method Effect of artificial viscosity frequency and Mach number on reflection coefficientfrom a vertical wall is also investigated The results of wave reflection from a vertical wall show thatartificial viscosity dissipates the wave energy If artificial viscosity is used wave reflection coefficient fromthe vertical wall decreases from 0 96 to 0 67 The calculation of reflection coefficient is based on methodintroduced by Goda and Suzuki 1976 for generation of regular wave Wave reflection coefficient value issensitive to wave frequency and Mach number By decreasing the wave frequency and Mach number up to0 05 the reflection coefficient becomes closer to experimental data reported in the literature As a last and most complicated problem the horizontal perforated plate with forty percent porosity is locatedat the water surface close to the end wall of the towing tank was simulated using complete 2 D Navier Stokes equations Results of perforated plate modeling were compared with Cho and Kim 2008 experimental data The wave profiles are in good agreement with reported experimental data It is found thatthe reflection coefficient of 0 62 and 0 71with respect to the dimensionless ratio of plate length towavelength matches closely to the results of experimental data In addition the reduction of wavelengths incase of constant plate length reduces the reflection coefficient which means that perforated plate effectivelyinteract with surface waves to lessen the wave reflection Key Words Perforated plate Wave reflection SPH SMP Particle neighbor search

دري، مجيد

مدل سازي عددي استهلاك انرژي موج به وسيله صفحه ي مشبك

صفحه ي مشبك , روش SPH , جستجوي ذرات مجاور , SMP