Implementation of turbulence models on 2d hybrid grids using an explicit/implicit multigrid algorithm

Download

index.pdf

Date

2011

Author

Yılmaz, Ali Emre

Metadata

Show full item record

Item Usage Stats

179
views

65
downloads

In this thesis study, implementation, numerical stability and convergence rate issues of turbulence modeling are explored. For this purpose, a one equation turbulence model, Spalart-Allmaras, and a two-equation turbulence model, SST k-w, are adapted to an explicit, cell centered, finite volume method based, structured / hybrid multi grid flow solver, SENSE2D, developed at TUBITAK-SAGE. Governing equations for both the flow and the turbulence are solved in a loosely coupled manner, however, each set of equations are solved using a coupled, semi-implicit solution algorithm. In multigrid solutions, the semi-implicit solution algorithm and the turbulence model equations are employed only in the finest level grid. As a result, stable and convergent numerical solutions are obtained. In order to validate the turbulence models and the semi-implicit solution algorithm implemented, turbulent flow solutions over a flat plate, RAE2822 airfoil and NLR7301 multi element airfoil are performed. The results are compared with the experimental data and the numerical results of the commercial CFD package FLUENT. It is shown that the numerical results obtained by SENSE2D are in good agreement with the experimental data and the FLUENT results. In addition to the turbulence modeling studies, convergence rate studies are also performed by multigrid and semi-implicit solution methods. It is shown that, the convergence rates of the semi-implicit solutions are increased about 5 times for single grid and 35% for multigrid solutions in comparison to the explicit solutions.

Subject Keywords

Turbulence., Aeronautics.

URI

http://etd.lib.metu.edu.tr/upload/12613783/index.pdf
https://hdl.handle.net/11511/21108

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Numerical simulation of non-reacting turbulent flows over a constant temperature solid surface in regression Karaeren, Cenker; Albayrak, Kahraman; Department of Mechanical Engineering (2007) In this study, an attempt is made to obtain convergent and stable solutions of the K-E turbulence model equations for non-reacting turbulent flows over an isothermal solid surface in regression. A physics based mathematical model is used to describe the flow and temperature field over the moving surface. The flow is assumed to be two-dimensional, unsteady, incompressible with boundary layer approximations. Parabolized form of the standard K-E equations is adopted to simulate turbulence in the flow. Regressi...
A tool for designing robust autopilots for ramjet missiles Kahvecioğlu, Alper; Alemdaroğlu, Hüseyin Nafiz; Department of Aerospace Engineering (2006) The study presented in this thesis comprises the development of the longitudinal autopilot algorithm for a ramjet powered air-to-surface missile. Ramjet Missiles have short time-of-flight, however they suffer from limited angle of attack margins due to poor operational-region characteristics of the ramjet engine. Because of such limitations and presence of uncertainties involved, Robust Control Techniques are used for the controller design. Robust Control Techniques not only provide an easy limitation/uncer...
Investigation of effect of design and operating parameters on acoustophoretic particle separation via 3D device-level simulations Sahin, Mehmet Akif; ÇETİN, BARBAROS; Özer, Mehmet Bülent (Springer Science and Business Media LLC, 2019-12-16) In the present study, a 3D device-level numerical model is implemented via finite element method to assess the effects of design and operating parameters on the separation performance of a microscale acoustofluidic device. Elastodynamic equations together with electromechanical coupling at the piezoelectric actuators for the stress field within the solid parts, Helmholtz equation for the acoustic field within fluid, and Navier-Stokes equations for the fluid flow are coupled for the simulations. Once the zer...
Navigation algorithms and autopilot application for an unmanned airvehicle Kahraman, Eren; Alemdaroğlu, Hüseyin Nafiz; Nalbantoğlu, Volkan; Department of Aerospace Engineering (2010) This study describes the design and implementation of the altitude and heading autopilot algorithms for a fixed wing unmanned air vehicle and navigation algorithm for attitude and heading reference outputs. Algorithm development is based on the nonlinear mathematical model of Middle East Technical University Tactical Unmanned Air Vehicle (METU TUAV), which is linearized at a selected trim condition. A comparison of nonlinear and linear mathematical models is also done. Based on the linear mathematical model...
Measurement of lift and drag in morphing wings using a high precision load cell Özkanaktı, Mehmet Harun; Özgen, Serkan; Department of Aerospace Engineering (2015) This thesis focuses on computational and experimental investigation of three different morphing wing planforms and a baseline wing planform using a commercial CFD software and load cell measurements for the validation of an optimization code developed in a separate study. The wing planforms of interest originate from an optimization tool that minimizes drag for a constant value of lift at a given velocity. The first planform of interest is the planform for optimized drag subject to 14 m/s freestream velocit...

Citation Formats

A. E. Yılmaz, “Implementation of turbulence models on 2d hybrid grids using an explicit/implicit multigrid algorithm,” M.S. - Master of Science, Middle East Technical University, 2011.