Instability - mean depth at cell centres - D-Flow Flexible Mesh - Delft3D
intro story D-Flow FM
D-Flow Flexible MeshD-Flow Flexible Mesh (D-Flow FM) is the new software engine for hydrodynamical simulations on unstructured grids in 1D-2D-3D. Together with the familiar curvilinear meshes from Delft3D 4, the unstructured grid can consist of triangles, pentagons (etc.) and 1D channel networks, all in one single mesh. It combines proven technology from the hydrodynamic engines of Delft3D 4 and SOBEK 2 and adds flexible administration, resulting in:
An overview of the current developments can be found here. The D-Flow FM - team would be delighted if you would participate in discussions on the generation of meshes, the specification of boundary conditions, the running of computations, and all kinds of other relevant topics. Feel free to share your smart questions and/or brilliant solutions!
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Instability - mean depth at cell centres
RM
Richard McSherry, modified 8 Years ago.
Instability - mean depth at cell centres
Youngling Posts: 2 Join Date: 2/5/13 Recent Posts 00
Hi,
I have noticed that there appears to be an instability when selecting the mean depth at cell centres, rather than the max depth of the four surrounding grid points. I am using a Z scheme, trying to model 3D temperature profiles in a lake - the temperature variation becomes unstable when the water level moves up and down. Has anyone else found this?
The documentation does suggest that using mean depth could have some issues associated with it. I have found that using max depth gives a much better temperature computation, but this scheme isn't well suited to areas with steep bathymetry - the depth is always significantly over-estimated (reducing horizontal cell size is an option, but not practical for me due to prohibitive run times).
Thanks in advance for any advice.
Richard
I have noticed that there appears to be an instability when selecting the mean depth at cell centres, rather than the max depth of the four surrounding grid points. I am using a Z scheme, trying to model 3D temperature profiles in a lake - the temperature variation becomes unstable when the water level moves up and down. Has anyone else found this?
The documentation does suggest that using mean depth could have some issues associated with it. I have found that using max depth gives a much better temperature computation, but this scheme isn't well suited to areas with steep bathymetry - the depth is always significantly over-estimated (reducing horizontal cell size is an option, but not practical for me due to prohibitive run times).
Thanks in advance for any advice.
Richard
Adri Mourits, modified 8 Years ago.
RE: Instability - mean depth at cell centres (Answer)
Yoda Posts: 1221 Join Date: 1/3/11 Recent Posts 00
Hi Richard,
Most important issue: Please switch to the recently tagged version 5.01.00.2163. This contains very thorough Z-model updates.
If that is not enough: Try adding the following two lines to the mdf-file (and remove other Trasol/Momsol lines):
Trasol= #iupw#
Momsol= #iupw#
This switches on some more implicit algorithms.
Regards,
Adri
Most important issue: Please switch to the recently tagged version 5.01.00.2163. This contains very thorough Z-model updates.
If that is not enough: Try adding the following two lines to the mdf-file (and remove other Trasol/Momsol lines):
Trasol= #iupw#
Momsol= #iupw#
This switches on some more implicit algorithms.
Regards,
Adri
RM
Richard McSherry, modified 8 Years ago.
RE: Instability - mean depth at cell centres
Youngling Posts: 2 Join Date: 2/5/13 Recent Posts 00
Hi Adri,
Thanks very much for the reply. I am presently trying to compile the new version and will test your suggestions.
Thanks again,
Richard
Thanks very much for the reply. I am presently trying to compile the new version and will test your suggestions.
Thanks again,
Richard