The influence of grid shape and grid size on hydraulic river modelling performance

Anouk Bomers (Corresponding Author), Ralph Mathias Johannes Schielen, Suzanne J.M.H. Hulscher

Research output: Contribution to journalArticleAcademicpeer-review

10 Citations (Scopus)
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Abstract

Grid shape (curvilinear/structured versus triangular/unstructured) and grid size affect model output. In this study structured, unstructured and hybrid grids with a high and low resolution were compared. As a case study, we use the Waal River (with main channel and floodplains). We studied simulated water levels using the six grids, considering equal main channel friction, which enabled to study the isolated effects of grid shape and size. The spread in simulated water levels was found to be rather large with a maximum deviation of 78 cm. Therefore, calibration was performed such that simulated water levels resembled measured water levels by adjusting the main channel friction. This enabled us to draw conclusions on the choice of optimal usage of the grids in engineering studies. Bathymetry accuracy and numerical friction, both as a result of grid resolution, and numerical viscosity as a result of grid shape play a vital role. The analysis shows that unstructured grids are affected most by the calibration which is reflected in the wide spreading of calibrated friction values. From the six grids studied, the hybrid grid with curvilinear grid cells in the main channel and triangular grid cells in the floodplain is recommended for hydraulic modelling since computation time is low, while model output shows sufficient accuracy.
Original languageEnglish
Pages (from-to)1273-1294
JournalEnvironmental fluid mechanics
Volume19
Issue number5
DOIs
Publication statusPublished - 21 Feb 2019

Keywords

  • UT-Hybrid-D

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