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

 


Message Boards

Parameters for Trachytope

JC
Jessica Chassereau, modified 6 Years ago.

Parameters for Trachytope

Youngling Posts: 15 Join Date: 4/21/11 Recent Posts
Hello Delft3D community!

I would like to use trachytopes to incorporate vegetation roughness as a function of water level/depth. I have two questions:

1. Do I need to specify multiple vegetation types for the same area in order to have it vary as a function of water level? For example, a platform with a maximum vegetation height of 1m would have a total of 10 vegetation types specified, where each type has a vegetation height that increases by 10 cm intervals?

2. Can someone please tell me what each parameter is in the following example definition file? There are 6 columns...what do each represent?

1 154 3 1.15 1.00 35.4

Thanks!

Jessica Chassereau Sullivan
Bert Jagers, modified 5 Years ago.

RE: Parameters for Trachytope

Jedi Knight Posts: 201 Join Date: 12/22/10 Recent Posts
Hi Jessica,


1. Do I need to specify multiple vegetation types for the same area in order to have it vary as a function of water level? For example, a platform with a maximum vegetation height of 1m would have a total of 10 vegetation types specified, where each type has a vegetation height that increases by 10 cm intervals?


It is not clear to me what you want to vary as function of water level.

If you specify one vegetation class of 1m high, water will flow through the vegetation if the depth is less than 1m, and it will start flowing through and over the vegetation if the depth is larger than 1m.

If you specify ten vegetation classes of 10cm, 20cm, ... 1m each representing 10% of the cell area, then you will be modelling an area with different types or ages of vegetation. At a depth 35cm, the 30% of the cell will have vegetation that is submerged, while the other 70% of the vegetation still extends through the water surface and hence the flow feels for these "plants" only the stems (up to 35cm).


2. Can someone please tell me what each parameter is in the following example definition file? There are 6 columns...what do each represent?
1 154 3 1.15 1.00 35.4


The first number indicates the trachytope number (say land use class, or roughness class). In the area file you will refer to this number.

The second number indicates the formula number to be used. In this case "154" points to the "Baptist 2" formulations with split flow resistance and bed roughness.

The remaining coefficients depend on the formula number. The meaning of these parameters is given by the table included in Appendix B.17.1 of the Delft3D-FLOW manual with reference to the equations given in Section 9.11.2. The numbers in your example should be interpreted as vegetation of 3 meters high [hv] with an accumulated stem diameter [n] of 1.15 meter (e.g. 23 stems of 5cm diameter) per meter squared, a dimensionless drag coefficient [cd] of 1, and an alluvial bed roughness [Cb] of 35.4 m^{1/2}/s.

Best regards,

Bert
LS
Louise S., modified 20 Days ago.

RE: Parameters for Trachytope

Youngling Posts: 1 Join Date: 10/1/20 Recent Posts
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