Implementation of turbulence models into a Navier-Stokes solver

Download
index.pdf
2004
Muşta, Mustafa Nail
Show full item record
214
views
155
downloads
In order to handle turbulent flow problems, one equation turbulence models are implemented in to a previously developed explicit, Reynolds averaged Navier-Stokes solver. Discretization of Navier-Stokes solver is based on cell-vertex finite volume formulation combined with single step Lax-Wendroff numerical method which is second order accurate in space. Turbulent viscosity is calculated by using one equation Spalart-Allmaras and Baldwin-Barth turbulence transport equations. For the discretization of Spalart-Allmaras and Baldwin-Barth equations, both finite volume scheme which is used for Navier-Stokes equation in this work and explicit finite difference discretization method are used. In order to increase the convergence rate of the solver, local time stepping technique is applied. Stabilization of non-physical oscillations resulting from the numerical scheme is maintained by adding second and fourth order artificial smoothing terms. Three test cases are considered. In order to validate the accuracy of the Navier-Stokes solver, solver is tested over a laminar flat plate. The results are compared with analytical solutions. Later, in order to check the performance of the turbulence models, turbulent flow over flat plate and turbulent transonic flow over NACA-0012 airfoil are handled. For turbulent flow over flat plate obtained results are compared with analytical and empirical solutions, whereas for transonic turbulent flow obtained results are compared with numerical and experimental solutions.
Mechanical engineering.
http://etd.lib.metu.edu.tr/upload/2/12605357/index.pdf
https://hdl.handle.net/11511/14507
Graduate School of Natural and Applied Sciences, Thesis

Suggestions

Implementation of the Spalart-Allmaras turbulence model to a two-dimensional unstructured Navier-Stokes solver
Aybay, Orhan; Aksel, Mehmet Haluk; Department of Mechanical Engineering (2004)
An unstructured explicit, Reynolds averaged Navier-Stokes solver is developed to operate on inviscid flows, laminar flows and turbulent flows and one equation Spalart-Allmaras turbulence modeling is implemented to the solver. A finite volume formulation, which is cell-center based, is used for numerical discretization of Navier-Stokes equations in conservative form. This formulation is combined with one-step, explicit time marching upwind numerical scheme that is the first order accurate in space. Turbulent...
Optimum Profile Modifications for the Minimization of Dynamic Transmission Error
ÖZTÜRK, VEYSEL YALIN; Ciğeroğlu, Ender; Özgüven, Hasan Nevzat (2014-08-28)
An optimization study is performed target being the reduction of dynamic transmission error (DTE) for a selected operational range, where the operating torque and speed ranges are defined. For this purpose, two different models, i.e. a single degree of freedom (SDOF) lumped gear dynamics model and a multi-degree of freedom (MDOF) lumped model of a gear pair which is combined with shaft and bearing dynamics are employed. The differences between the optimization results obtained through loaded static transmis...
Development of a multigrid accelerated euler solver on adaptively refined two- and three-dimensional cartesian grids
Çakmak, Mehtap; Aksel, Mehmet Haluk; Department of Mechanical Engineering (2009)
Cartesian grids offer a valuable option to simulate aerodynamic flows around complex geometries such as multi-element airfoils, aircrafts, and rockets. Therefore, an adaptively-refined Cartesian grid generator and Euler solver are developed. For the mesh generation part of the algorithm, dynamic data structures are used to determine connectivity information between cells and uniform mesh is created in the domain. Marching squares and cubes algorithms are used to form interfaces of cut and split cells. Geome...
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...
Computation of drag force on single and close-following vehicles
Örselli, Erdem; Çetinkaya, Tahsin Ali; Department of Mechanical Engineering (2006)
In this study, application of computational fluid dynamics to ground vehicle aerodynamics was investigated. Two types of vehicle models namely, Ahmed Body and MIRA Notchback Body and their scaled models were used. A commercial software "Fluent" was used and the effects of implementing different turbulence models with wall functions were observed. As a result, an appropriate turbulence model was selected to use in the study. The drag forces, surface pressure distributions and wake formations were investigate...
Citation Formats
M. N. Muşta, “Implementation of turbulence models into a Navier-Stokes solver,” M.S. - Master of Science, Middle East Technical University, 2004.
METU IIS - Integrated Information Service open@metu.edu.tr