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precondition-algorithm
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Numerical Simulation of Cavitating Flows with Thermodynamic Effects
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In this study, the numerical simulation of cavitating flows for cryogens fluids is performed. The algorithm employs the homogenous, multiphase Euler/Navier-Stokes equations with the interface capturing method. The thermodynamic and thermal effects substantially impact the cavitation dynamics of cryogenic fluids and therefore these effects should be considered by solving the energy equation in conjunction with the mass and momentum conservation, and updating the fluid physical properties. Here, two cavitation modeling strategies, namely, the barotropic cavitation model and the transport equation-based model are used. Both laminar and turbulent cavitating flows are studied in this work. For...
Solving Preconditioned Euler/Navier-Stokes Equations for Numerical Simulation of Cavitating Flows Using a Barotropic Model
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
Cavitation can occur in many fluid systems such as pumps, nozzles, hydrofoils and submarine vehicles and therefore, numerical modeling of this phenomenon has a significant importance. In this study, the numerical simulation of the cavitating flows through the Euler/Navier-Stokes equations employing the interface capturing method associated with a barotropic state law is performed. The system of governing equations is discretized using a cell-centered finite-volume algorithm and the fluxes are evaluated using a central-difference scheme. To account for density jumps across the cavity interface, the numerical dissipation terms with suitable density and pressure sensors are used. Since...
Application and Improvement of Preconditioning in Solution of Low Mach Number Flow, Using Compressible Flow Equation
, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim (Supervisor)
Abstract
Upwind methods for forward time marching integration of compressible flow equations, suffer low accuracy and convergence rate for very low mach numbers. Here we have used a preconditioning scheme to address this challenge. A preconditioner matrix is multiplied in the Euler flow equations. First we investigate subsonic flow around an airfoil to validate the numerical scheme used here, and to show grid independence of our solutions. Then very low mach numbers between 0.1 and 0.001 is solved and increase in accuracy and convergence rate is demonstrated. The proposed algorithm has flow parameters, which are studied here to find their effect on accuracy and convergence rate. The found results are...