The difference between them was the vertical coordinate, one sigma and the  DFlow Flexible Mesh  Delft3D
intro story DFlow FM
DFlow Flexible MeshDFlow Flexible Mesh (DFlow FM) is the new software engine for hydrodynamical simulations on unstructured grids in 1D2D3D. 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 DFlow 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!
=======================================================  Sub groups

Message Boards
The difference between them was the vertical coordinate, one sigma and the
LS
LUIS HENRIQUE SILVA, modified 7 Years ago.
The difference between them was the vertical coordinate, one sigma and the
Youngling Posts: 12 Join Date: 9/30/11 Recent Posts 00
Dear Adri,
I carried out two experiments, both forced by tide (amplitude and phase)
prescribed at a file *.bca. Both with 1 layer, size 92X91, barotropic. The
difference between them was the vertical coordinate, one sigma and the
other Z.
I think the results should be the same, but they are different: the run with
sigma coordinate was noisy ... Please, have a look in the figures, where the
water level is shown after an integration of 15 days.
Do you know what is happening ?
regards
Luis
I carried out two experiments, both forced by tide (amplitude and phase)
prescribed at a file *.bca. Both with 1 layer, size 92X91, barotropic. The
difference between them was the vertical coordinate, one sigma and the
other Z.
I think the results should be the same, but they are different: the run with
sigma coordinate was noisy ... Please, have a look in the figures, where the
water level is shown after an integration of 15 days.
Do you know what is happening ?
regards
Luis
Attachments:
Adri Mourits, modified 7 Years ago.
RE: The difference between them was the vertical coordinate, one sigma and
Yoda Posts: 1221 Join Date: 1/3/11 Recent Posts 00
Hi Luis,
That looks very weird indeed.
Although both calculations are with one layer, the actual algorithms are really different. The Zlayer algorithm is more explicit.If you use the same timestep for both simulations, I expect the sigmamodel to produce better results, which does not seem to be the case.
What happens if you reduce the time step?
If you scan the output between t=0 and t= 15 days, is there a point in time and/or space where it starts to become ugly?
Regards,
Adri
That looks very weird indeed.
Although both calculations are with one layer, the actual algorithms are really different. The Zlayer algorithm is more explicit.If you use the same timestep for both simulations, I expect the sigmamodel to produce better results, which does not seem to be the case.
What happens if you reduce the time step?
If you scan the output between t=0 and t= 15 days, is there a point in time and/or space where it starts to become ugly?
Regards,
Adri