intro story D-Flow FM

 

D-Flow Flexible Mesh

D-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:

  • Easier 1D-2D-3D model coupling, intuitive setup of boundary conditions and meteorological forcings (amongst others).
  • More flexible 2D gridding in delta regions, river junctions, harbours, intertidal flats and more.
  • High performance by smart use of multicore architectures, and grid computing clusters.
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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We have launched a new website (still under construction so expect continuous improvements) and a new forum dedicated to Delft3D Flexible Mesh.
Please follow this link to the new forum: 
/web/delft3dfm/forum
Post your questions, issues, suggestions, difficulties related to our Delft3D Flexible Mesh Suite on the new forum.

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** PLEASE TAG YOUR POST! **

  

 

Sub groups
D-Flow Flexible Mesh
DELWAQ
Cohesive sediments & muddy systems

 

Message Boards

Air pressure - Riemann instability

Fernando Barreto, modified 7 Years ago.

Air pressure - Riemann instability

Padawan Posts: 74 Join Date: 6/21/12 Recent Posts
I'm running simulations using the Research branch tangential velocity code (2012/02/17). As boundary conditions I'm using Riemann and tangential velocity. The problem appears when I enter with air pressure data. This causes instabilities in some parts of the boundary. Could this be related with the ''Atmospheric pressure correction added for Riemann boundaries in combination with 3d-profile'' added in the codes after 2012/02/27.

Regards,

Fernando.
riemann air pressure
Fernando Barreto, modified 7 Years ago.

RE: Air pressure - Riemann instability

Padawan Posts: 74 Join Date: 6/21/12 Recent Posts
I simulated with the last tag code (2824), using Riemann, wind speed, air pressure, and I found the same thing. I attached the picture. The instability is located in the south and east boundaries (like a rock thrown into a pond). Someone have any idea of how to correct it?

regards, Fernando

Attachments:

Fernando Barreto, modified 7 Years ago.

RE: Air pressure - Riemann instability

Padawan Posts: 74 Join Date: 6/21/12 Recent Posts
After making some tests I discovered that when I run with only Riemann + wind + air pressure I get no error. And when I run Riemann + temperature + salinity I also get no error. The problem appers when I simulate Riemann + baroclinic affects (bcc file) + wind + air pressure. I really make no idea of the cause of the problem.
LD
Leonardo de Jesus, modified 7 Years ago.

RE: Air pressure - Riemann instability (Answer)

Youngling Posts: 5 Join Date: 1/23/12 Recent Posts
Hi Fernando,

my guess is that your error is not related with the combination of Riemann BC and temperature/salinity. It seems to be related with how this properties are set at your boundary...
As in your runs with Riemann + atmospheric forcing terms are going well, I suggest you: take a look at your temperature/salinity boundary file (bbc file) and make sure that it is filled properly (I mean, check if there is some negative temperatures or unrealistic temperatures or salinities at your boundaries).

Hope this help,
Leonardo.
riemann
Fernando Barreto, modified 7 Years ago.

RE: Air pressure - Riemann instability

Padawan Posts: 74 Join Date: 6/21/12 Recent Posts
Thank you Leonardo, you were completely right. The source of the problem were bad values (negative) in the baroclinic (salinity, temperature) boundary condition (.bcc file).

Regars,

Fernando Barreto
Jonathan Ray Abat, modified 5 Years ago.

RE: Air pressure - Riemann instability

Youngling Posts: 11 Join Date: 7/10/14 Recent Posts
Hello Fernando,

I'm very curious how you do the research branch tangential velocity. How were you able to set the tangential part in Delft3D FLOW?

Warm Regards,


Jonathan
Qinghua Ye, modified 5 Years ago.

RE: Air pressure - Riemann instability

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
Hi Jonathan,

This function is still located in a research branch version. Notice that it is not a fully tested version, you may use it for research purpose. You may contact me by email for the downloading address.

Cheers,

Qinghua
Jonathan Ray Abat, modified 5 Years ago.

RE: Air pressure - Riemann instability

Youngling Posts: 11 Join Date: 7/10/14 Recent Posts
Hello Qinghua,

I have downloaded the research version of the tangential velocity and successfully compiled it. After I opened it, it seemed like its the same with the other Delft3D versions. I cannot find in the GUI where and how to input the tangential velocity.

I was pre-processing my data using OET and I don't understand how to have a combination of Riemann and Tangential velocity at the open boundaries.

Warm Regards,


Jonathan
Qinghua Ye, modified 5 Years ago.

RE: Air pressure - Riemann instability

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
HI Jonathan,

Very well done that you found the branch! I attached an example of bnd and bct for this specific input, see if you can make it work.

Cheers,

Qinghua

Attachments:

Jonathan Ray Abat, modified 5 Years ago.

RE: Air pressure - Riemann instability

Youngling Posts: 11 Join Date: 7/10/14 Recent Posts
Hello Qinghua,

I tried using your files but I'm having some errors. It says that bnd file has invalid boundary record and the import will be aborted.


Warm Regards,

Jonathan
Qinghua Ye, modified 5 Years ago.

RE: Air pressure - Riemann instability (Answer)

Jedi Council Member Posts: 610 Join Date: 3/2/11 Recent Posts
Hi Jonathan,

Are you checking out the correct branch:https://svn.oss.deltares.nl/repos/delft3d/branches/research/Deltares/20150310_tangential_boundary_conditions...?

Regards,

Qinghua
Jonathan Ray Abat, modified 5 Years ago.

RE: Air pressure - Riemann instability

Youngling Posts: 11 Join Date: 7/10/14 Recent Posts
Hello Qinghua,

The version I downloaded has a 5345 tag. I will download and compile the link you gave me and will give you an update.


Best,

Jonathan Ray Abat