Modeling Riverbed

MichaelMAB · January 25, 2017, 15:51

I am working on a thesis project attempting to model flow through a small stream and calculate the critical flow velocities and shear stresses necessary to initiate sediment transport. However, I am having trouble modeling the river geometry data in a suitable .stl format. I have a temporary academic license, so no access to support from Flow-3D staff.

I have several cross-sections of the river in the x-z plane located every 50m or so. I also have the GPS data, so I know where the river begins along the y plane. My question is, how do I take these xyz points and convert them into an .stl file? It seems that using a program like Civil-3D or ArcGIS would be difficult, because the conversion from TIN to .stl isn't an easy one. I was considering importing the points from excel into Solidworks, and then using the Loft function to connect each plane. Does anyone have a better solution?

I also need to make sure the surface roughness of the model matches that of the riverbed. Is there a way to specify roughness in Flow-3D? Can you change the fluid friction using the Chezy formula?

dmilano · February 3, 2017, 15:26

Look in to the raster/ASC import option. It'll import ESRI raster files for both topography and roughness so you can bypass the STL conversion.

Roughness is set in terms of the actual roughness height in the component properties->surface properties.

bfox48 · February 6, 2017, 12:23

Using the ASC is a good approach. There are also simple ways to import a surface from civil3D to an STL. In civil3D you will need to convert the surface object to 3D faces, Then extrude them so that it is now a solid 3D object. From here you can use the STLout command to export it to an stl file that can be imported into FLOW3D. There are several tutorials online that you can find through a google search.

January 25, 2017, 15:51	Modeling Riverbed	#1
MichaelMAB New Member Michael B Join Date: Jan 2017 Posts: 1 Rep Power: 0	I am working on a thesis project attempting to model flow through a small stream and calculate the critical flow velocities and shear stresses necessary to initiate sediment transport. However, I am having trouble modeling the river geometry data in a suitable .stl format. I have a temporary academic license, so no access to support from Flow-3D staff. I have several cross-sections of the river in the x-z plane located every 50m or so. I also have the GPS data, so I know where the river begins along the y plane. My question is, how do I take these xyz points and convert them into an .stl file? It seems that using a program like Civil-3D or ArcGIS would be difficult, because the conversion from TIN to .stl isn't an easy one. I was considering importing the points from excel into Solidworks, and then using the Loft function to connect each plane. Does anyone have a better solution? I also need to make sure the surface roughness of the model matches that of the riverbed. Is there a way to specify roughness in Flow-3D? Can you change the fluid friction using the Chezy formula?

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February 3, 2017, 15:26		#2
dmilano Member Join Date: Mar 2012 Posts: 72 Rep Power: 14	Look in to the raster/ASC import option. It'll import ESRI raster files for both topography and roughness so you can bypass the STL conversion. Roughness is set in terms of the actual roughness height in the component properties->surface properties.

February 6, 2017, 12:23		#3
bfox48 New Member brian Join Date: Apr 2012 Posts: 25 Blog Entries: 1 Rep Power: 14	Using the ASC is a good approach. There are also simple ways to import a surface from civil3D to an STL. In civil3D you will need to convert the surface object to 3D faces, Then extrude them so that it is now a solid 3D object. From here you can use the STLout command to export it to an stl file that can be imported into FLOW3D. There are several tutorials online that you can find through a google search.