TY - JOUR
T1 - The effect of a local mesh refinement on hydraulic modelling of river meanders
AU - Bilgili, Eray
AU - Bomers, Anouk
AU - Van lente, G. Jan‐willem
AU - Huthoff, Fredrik
AU - Hulscher, Suzanne J. M. H.
N1 - Funding Information:
This research is embedded in Netherlands Organisation for Scientific Research project 14506 which is partly funded by the Ministry of Economic Affairs and Climate Policy. Furthermore, the authors would like to thank the Dutch Ministry of Infrastructure for providing the data. Additionally, the authors would like to thank Mr. J. de Jong from Deltares for his valuable insights.
Funding Information:
Netherlands Organisation for Scientific Research, Grant/Award Number: 14506; Ministry of Economic Affairs and Climate Policy Funding information
Funding Information:
This research is embedded in Netherlands Organisation for Scientific Research project 14506 which is partly funded by the Ministry of Economic Affairs and Climate Policy. Furthermore, the authors would like to thank the Dutch Ministry of Infrastructure for providing the data. Additionally, the authors would like to thank Mr. J. de Jong from Deltares for his valuable insights.
Publisher Copyright:
© 2023 The Authors. River Research and Applications published by John Wiley & Sons Ltd.
PY - 2023/6/1
Y1 - 2023/6/1
N2 - Large-scale river models are generally discretized by relatively large mesh cells resulting in bathymetry discretization errors and numerical effects. These hydraulic models are generally calibrated by altering the bed roughness to compensate for these errors and effects. Consequently, the calibrated roughness values are mesh-dependent while generally local mesh refinements are executed after model calibration to study the effects of river interventions. This study shows both the errors caused by bathymetry discretization and numerical effects for locally refined meshes. First, schematised river meanders with a flat bed in the transverse flow direction are analysed to isolate the induced numerical effects by the mesh. Afterwards, a case study is considered to verify if similar mesh influences are found in natural river meanders. Curvilinear, triangular and hybrid (combination of curvilinear and triangular cells) meshes are used with different resolutions. The analysis shows that in the schematised river meanders lower depth-averaged flow velocities and larger water depths are simulated with coarser meshes. In the case study, substantial differences in hydrodynamics between the meshes are obtained suggesting that the bathymetry discretization is more influential than the numerical effects. Finally, it was found that triangular meshes, and rivers with narrow meander bends, are most sensitive to mesh resolution. Especially in these cases, it is desirable to refine the mesh at the desired locations before model calibration.
AB - Large-scale river models are generally discretized by relatively large mesh cells resulting in bathymetry discretization errors and numerical effects. These hydraulic models are generally calibrated by altering the bed roughness to compensate for these errors and effects. Consequently, the calibrated roughness values are mesh-dependent while generally local mesh refinements are executed after model calibration to study the effects of river interventions. This study shows both the errors caused by bathymetry discretization and numerical effects for locally refined meshes. First, schematised river meanders with a flat bed in the transverse flow direction are analysed to isolate the induced numerical effects by the mesh. Afterwards, a case study is considered to verify if similar mesh influences are found in natural river meanders. Curvilinear, triangular and hybrid (combination of curvilinear and triangular cells) meshes are used with different resolutions. The analysis shows that in the schematised river meanders lower depth-averaged flow velocities and larger water depths are simulated with coarser meshes. In the case study, substantial differences in hydrodynamics between the meshes are obtained suggesting that the bathymetry discretization is more influential than the numerical effects. Finally, it was found that triangular meshes, and rivers with narrow meander bends, are most sensitive to mesh resolution. Especially in these cases, it is desirable to refine the mesh at the desired locations before model calibration.
KW - UT-Hybrid-D
U2 - 10.1002/rra.4110
DO - 10.1002/rra.4110
M3 - Article
SN - 1535-1459
VL - 39
SP - 832
EP - 846
JO - River research and applications
JF - River research and applications
IS - 5
ER -