An AMG strategy for efficient solution of free-surface flows

Abstract

Purpose

An area of great interest in current computational fluid dynamics research is that of free-surface modelling (FSM). Semi-implicit pressure-based FSM flow solvers typically involve the solution of a pressure correction equation. The latter being computationally intensive, the purpose of this paper is to involve the implementation and enhancement of an algebraic multigrid (AMG) method for its solution.

Design/methodology/approach

All AMG components were implemented via object-oriented C++ in a manner which ensures linear computational scalability and matrix-free storage. The developed technology was evaluated in two- and three-dimensions via application to a dam-break test case.

Findings

AMG performance was assessed via comparison of CPU cost to that of several other competitive sparse solvers. The standard AMG implementation proved inferior to other methods in three-dimensions, while the developed Freeze version achieved significant speed-ups and proved to be superior throughout.

Originality/value

A so-called Freeze method was developed to address the computational overhead resulting from the dynamically changing coefficient matrix. The latter involves periodic AMG setup steps in a manner that results in a robust and efficient black-box solver.

Citation

Mowat, A.G.B., van den Bergh, W.J., Malan, A.G. and Wilke, D. (2016), "An AMG strategy for efficient solution of free-surface flows", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 26 No. 3/4, pp. 1172-1186. https://doi.org/10.1108/HFF-09-2015-0389