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

Prescribing equilibrium concentration at a single open boundary

AC
Alberto Canestrelli, modified 8 Years ago.

Prescribing equilibrium concentration at a single open boundary

Youngling Posts: 8 Join Date: 7/12/11 Recent Posts
Dear all,
I noticed that in Delft3D there is only the option to prescribe an equilibrium concentration (Neumann condition, NeuBcSand=true for sand and NeuBcMud=true for mud) at ALL the open inflow boundary, but it is not possible to prescribe it only at a particular boundary. I am trying to simulate the long term evolution of a river debouching in a tidal basin. I am prescribing a (non-equilibrium) entering concentration in the upstream boundary of the river, while I would like to have a Neumann condition at the downstream boundary, where I prescribe the tide. It looks like this is not possible, because if I have sand and I add NeuBcSand=true the Neumann condition applies to ALL the boundary and overwrite my upstream condition. or am I missing something?
thanks
cheers
Alberto
AC
Alberto Canestrelli, modified 8 Years ago.

RE: Prescribing equilibrium concentration at a single open boundary

Youngling Posts: 8 Join Date: 7/12/11 Recent Posts
Ok I have found the way to do it, you have just to prescribe a Thatcher-Harlemann time lag equal to -1. I did not see that possiblility at first.
Cheers
Alberto
AC
Alberto Canestrelli, modified 8 Years ago.

RE: Prescribing equilibrium concentration at a single open boundary

Youngling Posts: 8 Join Date: 7/12/11 Recent Posts
Mmm I noticed that if you prescribe the thatcher lag time =-1 also the salinity has the "equilibrium concentration" in the sense that a newmann condition dc/dx is applied to the boundary (i.e. for inflow the value inside the domain is copied on the boundary). That it is clearly not a good thing because it means that no salinity is entering the domain at any time, and if you start with some salinity inside the domain it fast exits the domain and it never comes back. It looks like its impossible to prescribe salinity and equilibrium sediment concentrations together at a single boundary. anybody confirming this?
Thanks
Alberto