Development of an all speed navier-stokes preconditioner for two and three dimensional flows on hybrid grids

Download
2015
Baş, Onur
In this study, a novel Mach uniform preconditioning method is developed for the solution of Euler/Navier-Stokes equations at subsonic and incompressible flow conditions. In contrast to the methods developed earlier in which the conservation of mass equation is preconditioned, the conservation of energy equation is preconditioned in the present method to enforce the divergence free constraint on the velocity field even at the limiting case of incompressible, zero Mach number flows. The proposed Mach-uniform preconditioning method does not have a singularity point at zero free-stream Mach number. The modified system of equations preserves the strong conservation form of the governing equations for compressible flows and recovers the artificial compressibility equations in the case of zero Mach number. Two and three dimensional preconditioned solvers are developed for validation and performance evaluation of the present formulation on a wide range of Mach number flows. The studied cases show the convergence acceleration, stability and accuracy of the present Mach uniform preconditioner in comparison to the non-preconditioned compressible flow solutions. The convergence acceleration achieved is similar to those of the well known preconditioned system of equations for low subsonic flows and to the artificial compressibility method for incompressible flows.

Suggestions

Comparison of method of lines and finite difference solutions of 2-D Navier-Stokes equations for transient laminar pipe flow
Selçuk, Nevin; Tanrikulu, S (2002-03-10)
Performances of method of lines (MOL) and finite difference method (FDM) were tested from the viewpoints of solution accuracy and central processing unit (CPU) time by applying them to the solution of time-dependent 2-D Navier-Stokes equations for transient laminar flow without/with sudden expansion and comparing their results with steady-state numerical predictions and measurements previously reported in the literature. Predictions of both methods were obtained on the same computer by using the same order ...
The dual reciprocity boundary element solution of helmholtz-type equations in fluid dynamics
Alsoy Akgün, Nagehan; Tezer Sezgin, Münevver; Department of Mathematics (2013)
In this thesis, the two-dimensional, unsteady, laminar and incompressible fluid flow problems governed by partial differential equations are solved by using dual reciprocity boundary element method (DRBEM). First, the governing equations are transformed to the inhomogeneous modified Helmholtz equations, and then the fundamental solution of modified Helmholtz equation is used for obtaining boundary element method (BEM) formulation. Thus, all the terms in the equation except the modified Helmholtz operator ar...
Analysis of single phase fluid flow and heat transfer in slip flow regime by parallel implementation of Lattice Boltzmann method on GPUS
Çelik, Sıtkı Berat; Sert, Cüneyt; Çetin, Barbaros; Department of Mechanical Engineering (2012)
In this thesis work fluid flow and heat transfer in two-dimensional microchannels are studied numerically. A computer code based on Lattice Boltzmann Method (LBM) is developed for this purpose. The code is written using MATLAB and Jacket software and has the important feature of being able to run parallel on Graphics Processing Units (GPUs). The code is used to simulate flow and heat transfer inside micro and macro channels. Obtained velocity profiles and Nusselt numbers are compared with the Navier-Stokes ...
Design and analysis of a vertical axis water turbine for river applications using computational fluid dynamics
Demircan, Eren; Aksel, Mehmet Haluk; Pınarcıoğlu, Mehmet Melih; Department of Mechanical Engineering (2014)
The main purpose of this study is to design a Darrieus rotor type vertical axis water turbine using Computational Fluid Dynamics (CFD) in order to be used in river currents. The CFD modeling is based on two dimensional numerical solution of the rotor motion using commercial Unsteady Reynolds Averaged Navier-Stokes solvers, Ansys Fluent and CFX. To validate the two dimensional numerical solution, an experimental Darrieus rotor type water turbine from literature is studied and performance of several turbulenc...
Identification of Viscous and Coulomb Friction in Motion Constrained Systems
YERLİKAYA, ÜMİT; Balkan, Raif Tuna (2018-07-09)
In this study, a simple and inexpensive method is developed in order to identify viscous and Coulomb frictions in systems with motion limitations. This method is used on a prototype. A series of tests are performed using position profiles with different speeds created according to motion limits in the systems. Using the data obtained from these tests, viscous and Coulomb friction characteristics are identified for both negative and positive motion directions. The method developed can also be used to determi...
Citation Formats
O. Baş, “Development of an all speed navier-stokes preconditioner for two and three dimensional flows on hybrid grids,” Ph.D. - Doctoral Program, Middle East Technical University, 2015.