FMA Challenge 2: Difference between revisions
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=Solution=
A sample solution has been presented, courtesy of BMT WBM.
==Cross section spacing, Grid Size, and Mesh Element Size==
Fixed grid models of different resolutions and a flexible mesh model were set up. The fixed grid domains were orientated north-south.
The coarsest fixed grid and flexible mesh resolutions were sufficiently detailed to represent the river bathymetry, so no 1D/2D coupling was incorporated. A fully 2D solution is preferable over a 1D/2D linked representation provided the 2D resolution of the primary flowpaths is sufficiently fine. A minimum recommended 2D resolution across the river for TUFLOW for this model is a 30m grid (it is recommended that a minimum of 4 fixed grid cells be used for modeling a primary flowpath). For this model the upper sections near the two inflows are not represented well, especially the northern Tributary Inflow. However, this is unlikely to have an adverse effect on the objectives of the modeling, but would affect the comparison to the high water marks near these inflows.
As there is no 1D/2D linking, Challenge 2 provided an opportunity to provide some comparisons between our three different 2D solvers. Results from TUFLOW (finite difference implicit solution), TUFLOW’s GPU Module (explicit finite volume GPU solver over a grid), and TUFLOW FV (explicit finite volume flexible mesh) are presented.
The number of cross sections, grids, or mesh elements used were as follows:<br>
{| align="center" class="wikitable" width="50%"
! style="background-color:#005581; font-weight:bold; color:white;"| 2D Domain
! style="background-color:#005581; font-weight:bold; color:white;" width=50%| Active 2D Cells/Elements
|-
| 10m (grid) || 727, 865 |
|-
| 15m (grid) || 323, 364 |
|-
| 30m (grid) || 80, 842 |
|-
| FM (Flexible Mesh)* || 17, 479 |
|}
*N.B. For the FM (Flexible Mesh) within the main flow channels the typical element width is 20 m and length 50 m (quadrilateral elements), and on the floodplains the typical size is 75 m to 100 m made up of quadrilaterals and triangles.
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