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! 

 

=======================================================
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.

=======================================================

** PLEASE TAG YOUR POST! **

 

 

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

 


Message Boards

RE: sediment transport with overland flow

AA
Anonymous Anonymous, modified 5 Years ago.

sediment transport with overland flow

Jedi Master Posts: 333 Join Date: 7/30/20 Recent Posts
Dear friends,

I am doing a model for sediment transport under storm surge. As I always expect, it is the flooding and receding of high water that transport sediment around. So I set a depth limit of 10cm for sediment transport, which says sediment transport is not calculated if the total depth is less than 10 cm.

But I just read something and realize the shallow water flow, which is known as overland flow or surface runoff, also can cause erosion and re-deposition. I don’t know much about this topic, and quite curious on the following:
• What is the relative contribution of overland flow to sediment transport during a high water event such as a storm surge?
• Does the sediment transport module in Delft3D has some special consideration for this process? Is it possible to utilize the bedload formula in Delft3D to model its effect? With the parameter SEDTHR, it seems Delft3D totally neglects the sediment process shallower than the SEDTHR. I can lower this threshold, but is there any applicable range with the existing sediment transport formulae in Delft3D?

It would be wonderful if any of the sediment modeler here can share your opinion or experience on this topic, or point me to some good literatures.

Thank you, and have a great weekend!

Ke
Richard Measures, modified 5 Years ago.

RE: sediment transport with overland flow

Jedi Knight Posts: 178 Join Date: 3/23/11 Recent Posts
Hi Ke,

Shear stress can be high with low flow depths - potentially generating high transport rates. By setting SEDTHR small (close to DRYFLC - wetting and drying threshold, saved in the mdf file) you should probably be able to include these effects. When setting SEDTHR and DRYFLC values very small through you will need to check that you are not generating instabilities around the wetting/drying front.

Cheers,
Richard
AA
Anonymous Anonymous, modified 5 Years ago.

RE: sediment transport with overland flow

Jedi Master Posts: 333 Join Date: 7/30/20 Recent Posts
Hi, Richard,

Thank you for your suggestion! I will try to reduce the SEDTHR with DRYFLC and see how it looks like (shear stress and sediment process) as you said.

But still, I might not be very confident about the results by applying the same formula to overland flow as those used for relatively deep water. As overland flow show a wide variety of flow conditions, but many sediment transport formula are designed for turbulent stream flow (An interesting paper is "sediment transport capacity of overland flow" by Juien and Simon). If you happen to know any previous study or literature on Delft3D model considering this process, please let me know.

Again, thank you and best regards!

Ke
AA
Anonymous Anonymous, modified 5 Years ago.

RE: sediment transport with overland flow

Jedi Master Posts: 333 Join Date: 7/30/20 Recent Posts
Hi, Saeed,

The result we observe, the accumulation of the dumped material, is not necessarily incorrect. It depends on many factors: What material is it? Cohesive or non-cohesive? What are the sediment properties?

I would suggest you doing a calculation by yourself using sediment properties and the formula in the model, see whether the current is really strong enough to move it or not.

Hope that helps, and best regards,

Ke
FJ
Fullerton Joseph, modified 3 Months ago.

RE: sediment transport with overland flow

Youngling Posts: 1 Join Date: 10/19/20 Recent Posts
I was looking for the information regarding the same. Keep sharing the info MyBalanceNow
MH
Max Henty, modified 2 Months ago.

RE: sediment transport with overland flow

Youngling Posts: 1 Join Date: 11/11/20 Recent Posts
CK
Clark Kent, modified 2 Months ago.

RE: sediment transport with overland flow

Youngling Posts: 1 Join Date: 11/11/20 Recent Posts
<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}-->Check your GameStop gift card balance on my gift card online. Each time you use your prepaid card balance GameStop, the amount of the purchase is deducted from the available balance on the card.

<!--td {border: 1px solid #ccc;}br {mso-data-placement:same-cell;}-->Check GameStop Gift Card Balance