Detached Eddy simulation of turbulent flow on 2D hybrid grids

Yırtıcı, Özcan
In this thesis study, Detached Eddy Simulation turbulence model is studied in two dimension mainly for flow over single element airfoils in high Reynolds numbers to gain experience with model before applying it to a three dimensional simulations. For this aim, Spalart-Allmaras and standard DES ,DES97, turbulence models are implemented to parallel, viscous, hybrid grid flow solver. The flow solver ,Set2d, is written in FORTRAN language. The Navier-Stokes equations are discretized by first order accurately cell centered finite volume method and solved explicitly by using Runge-Kutta dual time integration technique. Inviscid fluxes are computed using Roe flux difference splitting method. The numerical simulations are performed in parallel environment using domain decomposition and PVM library routines for inter-process communications. To take into account the effect of unsteadyness after the convergence is ensured by local time stepping technique for four order magnitude drop in density residual, global time stepping is applied for 20000 iterations. The solution algorithm is validated aganist the numerical and experimental studies for single element airfoils in subsonic and transonic flows. It is seen that Spalart-Allmaras and DES97 turbulence models give the same results in the non-seperated flows. Grey area is investigated by changing $C_{DES}$ coefficient. Modeled Stress Depletion which cause reduction of eddy viscosity is observed.


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Three-dimensional numerical simulations of a four-wing flapping micro aerial vehicle (FMAV) with actual experimentally captured wing membrane kinematics have been performed using an immersed boundary method Navier-Stokes finite volume solver. To successfully simulate the clap and fling motion involving the wing intersection, the numerical solver has been specifically modified to use a newly improved interpolation template searching algorithm to prevent divergence. Reasonable agreement was found between the ...
Citation Formats
Ö. Yırtıcı, “Detached Eddy simulation of turbulent flow on 2D hybrid grids,” M.S. - Master of Science, Middle East Technical University, 2012.