A two dimensional euler flow solver on adaptive cartesian grids

Siyahhan, Bercan
In the thesis work, a code to solve the two dimensional compressible Euler equations for external flows around arbitrary geometries have been developed. A Cartesianmesh generator is incorporated to the solver. Hence the pre-processing can be performed together with the solution within a single code. The code is written in the C++ programming language and its object oriented capabilities have been exploited to save memory in the data structure developed. The Cartesian mesh is formed by dividing squares successively into its four quadrants. The main advantage of using this type of a mesh is the ability to generate meshes around geometries of arbitrary complexity quickly and to adapt the mesh easily based on the solution. The main disadvantage of this method is that the treatment of the cells that are cut by the geometry. For the solution procedure Roe’s method as well as flux vector splitting methods are used for the flux evaluation. The flux vector splitting schemes used are van Leer, AUSM, AUSMD and AUSMV methods. Time discretization is performed using a multi-stage method. To increase the accuracy least squares reconstruction is employed. The code is validated by performing calculations around a NACA0012 airfoil profile. The effect of reconstruction is demonstrated by plotting the pressure coefficient on the airfoil. The distribution obtained using reconstruction is very close to the experimental one while there is a considerable deviation for the case without reconstruction. Also the shock capturing capabilities of different methods have been investigated. In addition the performance of each method is analyzed for flow around an NLR 7301 airfoil with a flap.


A genetic algorithm for 2d shape optimization
Chen, Wei Hang; Oral, Süha; Department of Mechanical Engineering (2008)
In this study, an optimization code has been developed based on genetic algorithms associated with the finite element modeling for the shape optimization of plane stress problems. In genetic algorithms, constraints are mostly handled by using the concept of penalty functions, which penalize infeasible solutions by reducing their fitness values in proportion to the degrees of constraint violation. In this study, An Improved GA Penalty Scheme is used. The proposed method gives information about unfeasible ind...
Analysis of thin walled open section tapered beams using hybrid stress finite element method
Akman, Mehmet Nazım; Oral, Süha; Department of Mechanical Engineering (2008)
In this thesis, hybrid stress finite element is formulated for the analysis of the isotropic, thin walled, open section beams with variable cross sections. The beam element has two nodes each having seven degrees of freedom. Assumption of stress field is sufficient to determine the element stiffness matrix. Axial, flexural and torsional effects are taken into account in the analysis. The methodology can be applied both to the tapered and the uniform beams. Throughout this study, firstly element cross-sectio...
Modal identification of nonlinear substructures and implementation in structural coupling analysis
Arslan, Özge; Özgüven, Hasan Nevzat; Department of Mechanical Engineering (2008)
In this work, a new method is suggested for the modal identification of nonlinear structures and for the use of the modal data in calculating response of the nonlinear system to harmonic excitation. Nonlinearity in mechanical structures is usually encountered in connection regions. In this study, the nonlinear part of such a structure is modeled as a single nonlinear element and modal parameters of the structure are obtained as a function of displacement amplitude. Identification and modeling of nonlinear e...
Parallel processing of three-dimensional navier-stokes equations for compressible flows
Şişman, Tahsin Çağrı; Aksel, Mehmet Haluk; Department of Mechanical Engineering (2005)
The aim of this study is to develop a code that is capable of solving three-dimensional compressible flows which are viscous and turbulent, and parallelization of this code. Purpose of parallelization is to obtain a computational efficiency in time respect which enables the solution of complex flow problems in reasonable computational times. In the first part of the study, which is the development of a three-dimensional Navier-Stokes solver for turbulent flows, first step is to develop a two-dimensional Eul...
Fully Coupled Smoothed Particle Hydrodynamics-Finite Element Method Approach for Fluid-Structure Interaction Problems With Large Deflections
Dincer, A. Ersin; Demir, Abdullah; Bozkuş, Zafer; Tijsseling, Arris S. (ASME International, 2019-08-01)
In this study, a combination of the smoothed particle hydrodynamics (SPH) and finite element method (FEM) solving the complex problem of interaction between fluid with free surface and an elastic structure is studied. A brief description of SPH and FEM is presented. Contact mechanics is used for the coupling between fluid and structure, which are simulated with SPH and FEM, respectively. In the proposed method, to couple meshfree and mesh-based methods, fluid and structure are solved together by a complete ...
Citation Formats
B. Siyahhan, “A two dimensional euler flow solver on adaptive cartesian grids,” M.S. - Master of Science, Middle East Technical University, 2008.