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Evaluation of a fourth-order finite-volume compact scheme for les with explicit filtering
, Article Numerical Heat Transfer, Part B: Fundamentals ; Volume 48, Issue 2 , 2005 , Pages 147-163 ; 10407790 (ISSN) ; Kazemzadeh Hannani, S. K ; Mashayek, F ; Sharif University of Technology
2005
Abstract
The accuracy of the large-eddy simulation (LES) of turbulent flows can be increased by using high-order numerical schemes in space and time, due to a decrease in numerical errors. This work investigates a high-order compact finite-volume scheme suitable for LES. The explicit fourth-order Runge-Kutta (RK) scheme for time marching and fourth-order compact schemes for spatial derivatives using a cell-averaged approach are implemented. Different subgrid-scale models and the effect of explicit filtering in a fully turbulent channel flow are studied. In this flow, the fourth-order compact finite-volume method in space, and fourth-order RK in time in conjunction with the dynamic Smagorinsky model...
Computational Simulation of Turbulent Endwall Effects in Gas Turbines, Using LES Approach
,
M.Sc. Thesis
Sharif University of Technology
;
Tayyebi Rahni, Mohammad
(Supervisor)
;
Ramezanizadeh, Mahdi
(Supervisor)
Abstract
The most common three-dimensional flows accuring in axial turbomachineries are endwall flows. These flows, which depend on inner hub and on external surface of airfoils are called secondary flows. In modern turbines, these flows reduce turbine efficiency up to about 3 percent.Many sientists are interested in investigation such flows. In this study, turbulent endwall flows are modeled using large eddy simulation approach. Also, SIMPLE algoritm and Smagorinsky subgrid scale model are used. Non-orthogonal curvilinear coordinate system and structural grid are implemented.To verify the results, they were compared with some existing experimental data which, showed that current numerical results...
Computational Simulation of a Pre-swirl Incompressible Turbulent Jet-into-Cross-Flow Problem, Using LES Approach
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Ramezanizadeh, Mahdi (Co-Advisor)
Abstract
Injection of jet into cross-flow has various applications, such as film cooling of gas turbine blades, reaction control jets for missiles and aircrafts, and mixing of air and fuel in combustion chambers. Velocity ratio (blowing ratio), momentum ratio, and streamwise jet inclination angle are important correlation parameters which have been studied extensively. However, not much work has been done on the jet swirling effects. The present work investigates computational simulation of a row of swirling square jets injected normally into a cross-flow. The swirl is introduced using two injectors discharged normally into the jet. Computational simulations were performed using LES approach with...
Investigation of Longitudinal Tabs Effects on Compound Triple Jets Configuration in Film Cooling, Applying Large Eddy Simulation Approach
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohamad (Supervisor) ; Ramezanizadeh, Mehdi (Supervisor)
Abstract
In the present work, large eddy simulation approach was employed to investigate flows such as backward facing step and internal channel flow, using Smagorinsky and explicit algebraic subgrid-scale models (EASSM) in OpenFOAM software. For this purpose, an explicit algebraic subgrid-scale model was added to OpenFOAM. Coupling pressure and velocity fields were applied to the PISO-SIMPLE (PIMPLE) algorithm. The focus of the present study was to assess various subgrid scale models, in order to predict the behavior of several flows, as well as their extensive numerical study. The results were compared to available experimental data showning that the EASSM results were more accurate than...