TITLE:
The Effect of Time-Stepping on the Accuracy of Green Element Formulation of Unsteady Convective Transport
AUTHORS:
Okey Oseloka Onyejekwe
KEYWORDS:
Boundary Element Method, Green Element Method, Unsteady Convective Transport Equation, Advection Dominant Transport
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.2 No.7,
June
17,
2014
ABSTRACT: Despite the significant number of boundary element method (BEM) solutions
of time-dependent problems, certain concerns still need to be addressed.
Foremost among these is the impact of different time discretization schemes on
the accuracy of BEM modeling. Although very accurate for steady-state problems,
the boundary element methods more often than not are computationally challenged
when applied to transient problems. For the work reported herein, we
investigate the level of accuracy achieved with different time-discretization
schemes for the Green element method (GEM) solution of the unsteady convective
transport equation. The Green element method (a modified BEM formulation)
solves the boundary integral theory (A Fredholm integral equation of the second
kind) on a generic element of the problem domain in a way that is typical of
the finite element method (FEM). In this integration process a new system of
discrete equations is produced which is banded and hence amenable to matrix
manipulations. This is subsequently deployed to investigate the proper
resolution in both space and time for the chosen transient 1D transport
problems especially those involving shock wave propagation and different types
of boundary conditions. It is found that for three out of the four numerical
models developed in this study, the new system of discrete element equations
generated for both space and temporal domains exhibits accurate characteristics
even for cases involving advection-dominant transport. And for all the cases considered,
the overall performance relies heavily on the temporal discretization scheme
adopted.