Record Details

Lattice Boltzmann Relaxation Scheme for Compressible Flows

Electronic Theses of Indian Institute of Science

View Archive Info
 
 
Field Value
 
Title Lattice Boltzmann Relaxation Scheme for Compressible Flows
 
Creator Kotnala, Sourabh
 
Subject Lattice Boltzmann Method (LBM)
Lattice Boltamann Models
Computational Fluid Dynanics
Compressible Fluid Flows
Incompressible Flows
Incompressible Flows - Numerical Methods
Boltzmann Equation
Kinetic Theory
Compressible Flows - Numerical Methods
Hypersonic Flows
LBRS Algorithm
Supersonic Flows
Aerospace Engineering
 
Description Lattice Boltzmann Method has been quite successful for incompressible
flows. Its extension for compressible (especially supersonic and hypersonic)
flows has attracted lot of attention in recent time. There have been some
successful attempts but nearly all of them have either resulted in complex
or expensive equilibrium function distributions or in extra energy levels.
Thus, an efficient Lattice Boltzmann Method for compressible fluid flows
is still a research idea worth pursuing for. In this thesis, a new Lattice
Boltzmann Method has been developed for compressible flows, by using the concept of a relaxation system, which is traditionally used as semilinear alternative for non-linear hypebolic systems in CFD. In the relaxation
system originally introduced by Jin and Xin (1995), the non-linear flux in a hyperbolic conservation law is replaced by a new variable, together with a relaxation equation for this new variable augmented by a
relaxation term in which it relaxes to the original nonlinear flux, in the limit of a vanishing relaxation parameter. The advantage is that instead of one non-linear hyperbolic equation, two linear hyperbolic equations need to be solved, together with a non-linear relaxation term. Based on the interpretation
of Natalini (1998) of a relaxation system as a discrete velocity Boltzmann equation, with a new isotropic relaxation system as the basic building block, a Lattice Boltzmann Method is introduced for solving the
equations of inviscid compressible flows. Since the associated equilibrium
distribution functions of the relaxation system are not based on a low Mach
number expansion, this method is not restricted to the incompressible limit.
Free slip boundary condition is introduced with this new relaxation system
based Lattice Boltzmann method framework. The same scheme is then extended
for curved boundaries using the ghost cell method. This new Lattice Boltzmann Relaxation Scheme is successfully tested on various bench-mark test cases for solving the equations of compressible flows such as shock tube problem in 1-D and in 2-D the test cases involving supersonic flow over a forward-facing step, supersonic oblique shock reflection from a flat plate, supersonic and hypersonic flows past half-cylinder.
 
Contributor Raghurama Rao, S V
 
Date 2018-03-09T04:58:42Z
2018-03-09T04:58:42Z
2018-03-09
2012
 
Type Thesis
 
Identifier http://hdl.handle.net/2005/3257
http://etd.ncsi.iisc.ernet.in/abstracts/4118/G26987-Abs.pdf
 
Language en_US
 
Relation G26987