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

Dispersion in WAQ

KL
KW Leung, modified 5 Years ago.

Dispersion in WAQ

Youngling Posts: 6 Join Date: 10/8/13 Recent Posts
My questions are about the parameters of "Uniform Dispersion" under dispersion in Delft3D-WAQ .

1) Are they the calibration parameters?

2) What are the typical value for coast zone?

3) I hear someone said that these parameters would be added to the dispersion obtained from FLOW, is it correct?
MJ
Michel Jeuken, modified 5 Years ago.

RE: Dispersion in WAQ (Answer)

Jedi Knight Posts: 154 Join Date: 1/21/13 Recent Posts
Hi,

1) Yes they are calibration factors, and very system depended. But it also depends on whether you have a 2D of 3D simulation. A 3D simulation can contain a more realistic gradient in flow speeds between the top and bottom layers, also depended on the number of layers.You still might need some dispersion, and typically a value of 1 m2/s is used.

In 2D simulations this effect of the gradient can be mimicked using higher values for horizontal dispersion. If horizontal dispersion is important, you are strongly advised to use a 3-dimensional model with at least 3 to 4 water layers.

2) Typical values for dispersion in 2D simulations are in the range of 5 to 20 m2/s

3) There is only additional dispersion in the vertical (so only in 3D simulations), since only vertical dispersion is picked up from the hydrodynamics. However, as these values may be unrealistically small, you can enter a minimal value for the vertical dispersion.

Michel
KL
KW Leung, modified 5 Years ago.

RE: Dispersion in WAQ

Youngling Posts: 6 Join Date: 10/8/13 Recent Posts
Thank you very much.

I would like to know what parameter is used to test the dispersion coefficient correct or not, that is to say how to calibrate the dispersion coefficient.

Thank you again.
MJ
Michel Jeuken, modified 5 Years ago.

RE: Dispersion in WAQ

Jedi Knight Posts: 154 Join Date: 1/21/13 Recent Posts
Hi,

To calibrate dispersion you usually take a measured, conservative substance that shows some gradient in the area studied. Usually this will be salinity. Lower dispersion should lead to steeper gradients.

Michel