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Development of Chebyshev Collocation Spectral Lattice Boltzmann Method for Solution of LowSpeed Flows
, M.Sc. Thesis Sharif University of Technology ; Hejranfar, Kazem (Supervisor)
Abstract
In this study, a Chebyshev collocation spectral lattice Boltzmann method (CCSLBM) is developed and assessed for the computation of low speed flows. Both steady and unsteady flows are considered here. The discrete Boltzmann equation (DBE) with the Bhatnagar-Gross-Krook (BGK) approximation based on the pressure distribution function is considered and the space discretization is performed by the Chebyshev collocation spectral method to achieve a highly accurate flow solver. To provide accurate unsteady solutions, the time integration of the temporal term in the LB equation is made by the fourth-order Runge-Kuta scheme. To achieve numerical stability and accuracy, the physical boundary...
Experimental Investigation of Geometric Parameters Effect on Energy Harvesting from FIV in Bluff Bodies
, M.Sc. Thesis Sharif University of Technology ; Ebrahimi, Abbas (Supervisor)
Abstract
The purpose of this research is to design and construct a test stand for the study of the kinematic and flow pattern of bluff bodies oscillating motion due to the induction of wake vortices. An experimental investigation was conducted to explore the effect of bluff bodies cross section to optimize the amount of electrical energy withdraw by electromagnetic harvester. The tests are carried out on cylinders with square section and rectangular sections with a length to width ratio of 1/2 and 2/1 and height of 50 cm, at speeds of 5 to 35 m/s in eiffel type wind tunnel. The effect of cylinder cross-section on the amount of energy harvested showed that the amplitude of oscillation in square-shaped...
Chebyshev collocation spectral lattice boltzmann method in generalized curvilinear coordinates
, Article Computers and Fluids ; Volume 146 , 2017 , Pages 154-173 ; 00457930 (ISSN) ; Hajihassanpour, M ; Sharif University of Technology
Abstract
In this work, the Chebyshev collocation spectral lattice Boltzmann method is implemented in the generalized curvilinear coordinates to provide an accurate and efficient low-speed LB-based flow solver to be capable of handling curved geometries with non-uniform grids. The low-speed form of the D2Q9 and D3Q19 lattice Boltzmann equations is transformed into the generalized curvilinear coordinates and then the spatial derivatives in the resulting equations are discretized by using the Chebyshev collocation spectral method and the temporal term is discretized with the fourth-order Runge–Kutta scheme to provide an accurate and efficient low-speed flow solver. All boundary conditions are...
A comparative study of two preconditioners for solving 3D inviscid low speed flows
, Article Applied Mechanics and Materials ; Volume 110-116 , 2012 , Pages 423-430 ; 16609336 (ISSN) ; 9783037852620 (ISBN) ; Moghadam, R. K ; Sharif University of Technology
2012
Abstract
In the present study, two preconditioners proposed by Eriksson, and Choi and Merkel are implemented on a 3D upwind Euler flow solver on unstructured meshes. The mathematical formulations of these preconditioning schemes for the set of primitive variables Q→p 1=[ρ u v , w p] T are drawn and their eigenvalues and eigenvectors are compared with each others. A cell-centered finite volume Roe's method is used for discretization of the 3D preconditioned Euler equations. The accuracy and performance of these preconditioning schemes are examined by computing low Mach number flows over the ONERA M6 wing for different conditions