Development of discontinuous galerkin method 2 dimensional flow solver

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2019

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Güngör, Osman

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In this work, 2 dimensional ﬂow solutions of Euler equations are presented from the developed discontinuous Galerkin method ﬁnite element method (DGFEM) solver on unstructured grids. Euler equations govern the inviscid and adiabatic ﬂows with a set of hyperbolic equations. The discretization of governing equations for DGFEM is given in detail. The DGFEM discretization provides high order solutions on an element-compact stencil hence only elements having common boundary are coupled. The required elementwise operations and mathematical operations are revisited and derivations are provided when necessary. Among the two major approaches, modal and nodal, nodal DGFEM is employed. Gaussian quadrature is utilized in the evaluation of volume and surface integrals. The ﬂux through the cell boundaries are calculated through ﬂux functions and several ﬂux functions are implemented and compared. Proper boundary conditions are employed on the solution space boundaries. Severaltestcasesinliteratureareusedforveriﬁcationandvalidationpurposes. The high order accuracy is easily achieved in problems with smooth solutions. On the other hand, problems with shocks requires stabilization techniques which may limit the order of accuracy or degrade solution success. The satisfactory results are obtained with comparison of experimental results which are carefully selected considering the ﬁdelity of governing equations. Moreover, importance of curved wall boundary representations in high order methods are experienced. Furthermore, effect of grid adaptation around shocks or discontinues is pointed out.

Subject Keywords

Computational fluid dynamics., Keywords: Computational Fluid Dynamics, Discontinuous Galerkin, High Order Accuracy, Finite Element, Euler Equations, Aerodynamics.

URI

http://etd.lib.metu.edu.tr/upload/12624449/index.pdf
https://hdl.handle.net/11511/44653

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

O. Güngör, “Development of discontinuous galerkin method 2 dimensional flow solver,” Thesis (M.S.) -- Graduate School of Natural and Applied Sciences. Aerospace Engineering., Middle East Technical University, 2019.