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

Nesting Limitations for Tidal Model in Delft Dashboard

JM
John McDowell, modified 1 Year ago.

Nesting Limitations for Tidal Model in Delft Dashboard

Youngling Posts: 13 Join Date: 9/6/17 Recent Posts

Hi there,

I've had some success with generating nested tidal FLOW results forced with astronomic and then time series boundaries in Delft Dashboard. Really pleased with the results. My thanks to all those that developed the software and documentation.

I have two questions about the limitations of nesting:

Firstly, is it possible to perform more than two layers of nesting in Delft Dashboard? If so, can someone please describe the exact procedure? My attempts so far have simply passed the results from my most coarse grid to the boundaries of my two finer grids (no intermediate nesting step, as desired). Is it possible to generate an admin file (nesting1) for a subsequent nesting run, while running an existing nested2 run?

My second question also relates to nesting. The Alpha value in the boundary conditions essentially relates to how reflective the boundary is, and is based on the size of the grid. For nested grid boundaries, what should this Alpha value be? My model seems to be very sensitive to this parameter, and I get quite different results with relatively small changes in Alpha. I had hoped that nesting would increase the accuracy of my models, but it has introduced a high uncertainty in the form of the Alpha parameter. Is my best bet to still base it on the grid domain size? Or should I leave it blank - if there were no boundary then the model would pass the results to the next grid point with no need for reflection? Any advice on this matter would be very much appreciated.

Thanks in advance,

John

RC
Rita Carrasco, modified 1 Year ago.

RE: Nesting Limitations for Tidal Model in Delft Dashboard

Padawan Posts: 26 Join Date: 7/23/13 Recent Posts

John,

 

Did you try sed transport in the two-level nesting? if so, did you get any error?

 

cheers

Rita

JM
John McDowell, modified 1 Year ago.

RE: Nesting Limitations for Tidal Model in Delft Dashboard

Youngling Posts: 13 Join Date: 9/6/17 Recent Posts

HI Rita,

No I wasn't looking at sediment transport, purely flow velocities for potential tidal energy applications.

Probably not the most efficient way, but I have set up multiple nesting runs to pass the rounds through several nested grids. Have you had any luck in doing multiple nesting layers in a single run?

RC
Rita Carrasco, modified 1 Year ago.

RE: Nesting Limitations for Tidal Model in Delft Dashboard

Padawan Posts: 26 Join Date: 7/23/13 Recent Posts

Nops. Only works with purely hydrodynamics.

Thanks for your reply

 

YX
yu jia xin, modified 1 Year ago.

RE: Nesting Limitations for Tidal Model in Delft Dashboard

Youngling Posts: 5 Join Date: 12/1/18 Recent Posts

Hello, I am also using DDB to do nesting. I am calculating a flow model of a large area, which is two-dimensional. Then the water quality model wants to take a smaller area to make three-dimensional. So I want to use nesting, otherwise the whole area will take a long time to calculate in three-dimensional terms, but using DDB to do nesting is always unsuccessful. Looking at your success in nesting, I would like to ask you how to achieve this process. Can you give me some advice? Thank you very much.

RC
Rita Carrasco, modified 1 Year ago.

RE: Nesting Limitations for Tidal Model in Delft Dashboard

Padawan Posts: 26 Join Date: 7/23/13 Recent Posts

Hi Yu

 

Sorry, never tried with three-dimensional models. Have you tried the nesting tool from delft3d menu instead of dahsboard? I think it migth work better. You can prepare your models in the dashboard, and run them in the delft3d.

cheers

YX
yu jia xin, modified 1 Year ago.

RE: Nesting Limitations for Tidal Model in Delft Dashboard

Youngling Posts: 5 Join Date: 12/1/18 Recent Posts

First of all, thanks for your reply. I'll try nesting first. If I have any questions, I'll come back and ask you. Thank you very much.