Numerical modeling of general compressible multi-phase flows

Download

index.pdf

Date

2013

Author

Kalpaklı, Bora

Metadata

Show full item record

Item Usage Stats

269
views

136
downloads

In this thesis, some novel methods for solution of compressible, multi-phase flows on unstructured grids were developed. The developed methods are especially advantageous for interface problems, while they are also applicable to multi-phase flows containing mixtures as well as particle suspensions. The first method studied was a multi-dimensional, multi-phase Godunov method for compressible multi-phase flows. This method is based on the solution of a hyperbolic equation system for compressible multi-phase flows. There are several difficulties with this hyperbolic equation system due to non-conservative volume fraction equation and non-conservative terms also known as throttling therms existing in momentum and energy equations. Robust and accurate multi-dimensional discretization of these terms were derived based on Abgrall \cite{Abgrall} criterion. Next a new method based on discrete equations for multi-dimensional and multiphase problems on unstructured grids was developed. This method resolves all the problems associated with the non-conservative equations and terms. The high artificial numerical mixing of phase interfaces associated with available compressible schemes was resolved with a novel volume fraction differencing scheme. The developed differencing scheme used for volume fraction is the only scheme providing comparable resolution of the interfaces with tracking methods on multi-dimensional unstructured grids and very robust compared to other interface capturing methods studied in the related literature. The resulting methods provide ignorable numerical mixing of phase interfaces on ustructured solution grids while giving physically correct results for pressure and energy in contrast to other methods available in the literature. In addition to these solution methods, some special boundary conditions and preconditioning methods for low speed steady flows were applied. For high spatial resolution, combinations of linear reconstruction and Weighted Average Flux (WAF) methods were also applied in some problems.

Subject Keywords

Fluid dynamics., Numerical analysis

URI

http://etd.lib.metu.edu.tr/upload/12616653/index.pdf
https://hdl.handle.net/11511/23178

Collections

Graduate School of Natural and Applied Sciences, Thesis

Suggestions

OpenMETU
Core

Incompressible flow simulations using least squares spectral element method on adaptively refined triangular grids Akdağ, Osman; Sert, Cüneyt; Department of Mechanical Engineering (2012) The main purpose of this study is to develop a flow solver that employs triangular grids to solve two-dimensional, viscous, laminar, steady, incompressible flows. The flow solver is based on Least Squares Spectral Element Method (LSSEM). It has p-type adaptive mesh refinement/coarsening capability and supports p-type nonconforming element interfaces. To validate the developed flow solver several benchmark problems are studied and successful results are obtained. The performances of two different triangular ...
Numerical investigation of free surface and pipe flow problems by smoothed particle hydrodynamics Dinçer, Ali Ersin; Bozkuş, Zafer; Department of Civil Engineering (2017) In the present study, a two-dimensional (2D) computer code for free surface and pipe flows is developed by using Smoothed Particle Hydrodynamics (SPH) approach. For free surface flow problem, idealized dam break problems are investigated numerically. The results of three recently published experimental studies are used to validate the numerical solutions. In addition to mesh-free particle method, SPH with a novel boundary treatment model proposed in the present study, mesh-based methods with turbulence and ...
An Efficient Numerical Solution Method for Reflectarrays of Varying Element Sizes Ercil, Erdinc; Alatan, Lale; Aydın Çivi, Hatice Özlem (2015-12-01) A novel method is developed for the efficient solution of reflectarrays of variable size elements. The method relies on using characteristic modes (CM) as macro basis functions and reusing the dominant CM of the resonant element for all elements in the reflectarray. This utilization leads to obtaining a reduced matrix system where the number of unknowns is drastically decreased. As far as the far field is concerned, accurate results are achieved even with a single CM. The accuracy is attained owing to prese...
Numerical simulation of advective Lotka-Volterra systems by discontinuous Galerkin method Aktaş, Senem; Karasözen, Bülent; Uzunca, Murat; Department of Scientific Computing (2014) In this thesis, we study numerically advection-diffusion-reaction equations arising from Lotka-Volterra models in river ecosystems characterized by unidirectional flow. We consider two and three species models which include competition, coexistence and extinction depending on the parameters. The one dimensional models are discretized by interior penalty discontinuous Galerkin model in space. For time discretization, fully implicit backward Euler method and semi-implicit IMEX-BDF methods are used. Numerical ...
Boundary element method solution of initial and boundary value problems in fluid dynamics and magnetohydrodynamics Bozkaya, Canan; Tezer, Münevver; Department of Mathematics (2008) In this thesis, the two-dimensional initial and boundary value problems invol\-ving convection and diffusion terms are solved using the boundary element method (BEM). The fundamental solution of steady magnetohydrodynamic (MHD) flow equations in the original coupled form which are convection-diffusion type is established in order to apply the BEM directly to these coupled equations with the most general form of wall conductivities. Thus, the solutions of MHD flow in rectangular ducts and in infinite regions...

Citation Formats

B. Kalpaklı, “Numerical modeling of general compressible multi-phase flows,” Ph.D. - Doctoral Program, Middle East Technical University, 2013.