# 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!

## Message Boards

### Question about the input parameter for porous

KT

#### Question about the input parameter for porous

Youngling Posts: 11 Join Date: 7/5/13
Dear all,

I have a question about the input parameter for a porous plate, "Friction coefficient of the quadratic friction".
According to the flow manual, I understand this as closs-U.
I calculated the parameter based on the equation (10.71) and obtained a value of 10^-1 order.
Each values are the below.
g=9.8 m/s^2, deltax=10 m, Um,n=0.02 m/s, kshi(u)-kshi(d)= 0.00001 m.

However, the examples on B.3.3 Porous Plate demonstrate values of 800 and 1000.
These values seem way too much.

Could you help me understand in what kind of case these large values come up?
Also, please correct me if my understanding toward the input parameter for a porous plate is wrong.