Coarsening of three-dimensional structured and unstructured grids for subsurface flow

Jørg Espen Aarnes*, Vera Louise Hauge, Yalchin Efendiev

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

We present a generic, semi-automated algorithm for generating non-uniform coarse grids for modeling subsurface flow. The method is applicable to arbitrary grids and does not impose smoothness constraints on the coarse grid. One therefore avoids conventional smoothing procedures that are commonly used to ensure that the grids obtained with standard coarsening procedures are not too rough. The coarsening algorithm is very simple and essentially involves only two parameters that specify the level of coarsening. Consequently the algorithm allows the user to specify the simulation grid dynamically to fit available computer resources, and, e.g., use the original geomodel as input for flow simulations. This is of great importance since coarse grid-generation is normally the most time-consuming part of an upscaling phase, and therefore the main obstacle that has prevented simulation workflows with user-defined resolution. We apply the coarsening algorithm to a series of two-phase flow problems on both structured (Cartesian) and unstructured grids. The numerical results demonstrate that one consistently obtains significantly more accurate results using the proposed non-uniform coarsening strategy than with corresponding uniform coarse grids with roughly the same number of cells.

Original languageEnglish (US)
Pages (from-to)2177-2193
Number of pages17
JournalAdvances in Water Resources
Volume30
Issue number11
DOIs
StatePublished - Nov 1 2007

Keywords

  • Grid generation
  • Porous media
  • Two-phase flow
  • Upscaling

ASJC Scopus subject areas

  • Water Science and Technology

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