Boundary conditions in a spillway

miguel7799 · November 7, 2012, 10:07

Hi. I was trying to model the flow in a spillway but at the moment im having some problems in boudary conditions. I would like to difine the entrace fluid elevation but my geometry isnt ortonormal to the axis.

I have another question related to the mesh. I want to create a mesh only where spliway is. I just dont know if that is possible and how to do it. I will attach a image.

Jibran · November 8, 2012, 07:09

As far as I know, your geometry has to be aligned with the axis since you can only specify the initial pressure field in x, y or z direction. For, creating the mesh, you should try the multi block meshing technique. It would definitely save you a lot of time considering your geometry. I am new to Flow-3D, so maybe someone else can answer you better.

miguel7799 · November 8, 2012, 10:17

I read that i can use stl file to define where initial water is and then let the gravity works. I just dont know how to do it. Anyway wont multi block extend the simulation time? and increase truncation errors?

Jibran · November 9, 2012, 05:16

Multi block technique would definitely be faster! Instead of meshing the whole block domain you can just focus on the region where the spillway is. See Flow-3D help for more details (Multi-Block Meshes). I don't think so it would be a cause of significant errors provided there is a smooth transition between adjacent mesh blocks.

Also go through the "Reducing Memory Use" topic in FLow-3D help, it might be useful.

miguel7799 · November 10, 2012, 12:35

thanks a lot. I will use multi-block for sure. Anyway i will need to know the flow caractheristics in certain sections. I read that i will need to use baffle. How can i set baffles in exact location that i need? Can i draw a plan in autocad and then use stl plan to turn into a baffle?

Jibran · November 13, 2012, 08:36

I don't think u need to do that. Please check 'Flux Surfaces' in help.

miguel7799 · December 1, 2012, 17:06

I have free surface profiles in certain sections in the tunnel from physical model and i need to compare that profiles to results in my CFD model.

I will like to ask if anybody has some idea to get free surface section profiles for a certain section from my CFD model. Maybe i will need to use a post-processor software right?

Im trying to open the results with Paraview but i just cant :S

Can somebody help me please?

miguel7799 · December 6, 2012, 07:26

anyone? I tried with EnSight free, but there are some limitations that make it impossible to opening the file.

November 7, 2012, 10:07	Boundary conditions in a spillway	#1
miguel7799 New Member Miguel Join Date: Oct 2012 Posts: 7 Rep Power: 14	Hi. I was trying to model the flow in a spillway but at the moment im having some problems in boudary conditions. I would like to difine the entrace fluid elevation but my geometry isnt ortonormal to the axis. I have another question related to the mesh. I want to create a mesh only where spliway is. I just dont know if that is possible and how to do it. I will attach a image.

December 1, 2012, 17:06		#7
miguel7799 New Member Miguel Join Date: Oct 2012 Posts: 7 Rep Power: 14	I have free surface profiles in certain sections in the tunnel from physical model and i need to compare that profiles to results in my CFD model. I will like to ask if anybody has some idea to get free surface section profiles for a certain section from my CFD model. Maybe i will need to use a post-processor software right? Im trying to open the results with Paraview but i just cant :S Can somebody help me please? Last edited by miguel7799; December 6, 2012 at 07:24.

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November 8, 2012, 07:09		#2
Jibran Member Jibran Join Date: Oct 2012 Location: UK Posts: 61 Blog Entries: 1 Rep Power: 15	As far as I know, your geometry has to be aligned with the axis since you can only specify the initial pressure field in x, y or z direction. For, creating the mesh, you should try the multi block meshing technique. It would definitely save you a lot of time considering your geometry. I am new to Flow-3D, so maybe someone else can answer you better.

November 8, 2012, 10:17		#3
miguel7799 New Member Miguel Join Date: Oct 2012 Posts: 7 Rep Power: 14	I read that i can use stl file to define where initial water is and then let the gravity works. I just dont know how to do it. Anyway wont multi block extend the simulation time? and increase truncation errors?

November 9, 2012, 05:16		#4
Jibran Member Jibran Join Date: Oct 2012 Location: UK Posts: 61 Blog Entries: 1 Rep Power: 15	Multi block technique would definitely be faster! Instead of meshing the whole block domain you can just focus on the region where the spillway is. See Flow-3D help for more details (Multi-Block Meshes). I don't think so it would be a cause of significant errors provided there is a smooth transition between adjacent mesh blocks. Also go through the "Reducing Memory Use" topic in FLow-3D help, it might be useful.

November 10, 2012, 12:35		#5
miguel7799 New Member Miguel Join Date: Oct 2012 Posts: 7 Rep Power: 14	thanks a lot. I will use multi-block for sure. Anyway i will need to know the flow caractheristics in certain sections. I read that i will need to use baffle. How can i set baffles in exact location that i need? Can i draw a plan in autocad and then use stl plan to turn into a baffle?

November 13, 2012, 08:36		#6
Jibran Member Jibran Join Date: Oct 2012 Location: UK Posts: 61 Blog Entries: 1 Rep Power: 15	I don't think u need to do that. Please check 'Flux Surfaces' in help.

December 6, 2012, 07:26		#8
miguel7799 New Member Miguel Join Date: Oct 2012 Posts: 7 Rep Power: 14	anyone? I tried with EnSight free, but there are some limitations that make it impossible to opening the file.