Parameters for Trachytope  DFlow Flexible Mesh  Delft3D
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DFlow Flexible MeshDFlow Flexible Mesh (DFlow FM) is the new software engine for hydrodynamical simulations on unstructured grids in 1D2D3D. 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:
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Parameters for Trachytope
JC
Jessica Chassereau, modified 6 Years ago.
Parameters for Trachytope
Youngling Posts: 15 Join Date: 4/21/11 Recent Posts 00
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
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 6 Years ago.
RE: Parameters for Trachytope
Jedi Knight Posts: 201 Join Date: 12/22/10 Recent Posts 10
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 Delft3DFLOW 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
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 Delft3DFLOW 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 5 Months ago.
RE: Parameters for Trachytope
Youngling Posts: 1 Join Date: 10/1/20 Recent Posts 00
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