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-   -   PKweir with Flow-3D 9.3 (http://www.cfd-online.com/Forums/flow-3d/27237-pkweir-flow-3d-9-3-a.html)

Julien October 2, 2008 03:56

PKweir with Flow-3D 9.3
 
Hello dears users of Flow-3D,

I need help concerning the modelling of a flow over a PKweir (sort of labyrinth weir), The problem is the geometry of that structure. Which mesh should I use? Has anybody already make such simulation?

Thanks

Julien


Byongjun Park October 2, 2008 04:46

PK weir simulation? It's very exciting!
 
Hi, Julien.

Will you simulate PK weir? Wow, it's very exciting!

Making the geometry is easy if you can use 3rd-party CAD S/Ws. When I make geometry of structure as STL file, I use Solid Edge version 20. How about using it?

If you need a help and send me the drawing of structure, I can help making STL file and show some input file. (I have a input file of labyrinth weir simulation.)

Good luck!

Julien October 2, 2008 05:20

Re: PK weir simulation? It's very exciting!
 
Hi Byongjun Park,

In fact, the geometry is not exactly my problem : using Autocad 2005 (a bit old, but efficient!), I have already a good solid (stl). I have already run simulations, but I am a bit far away from the referency data (specific flowrate)...I don't know where it comes from...I suspect my mesh...

I have read about labyrinth weir simulation (Brains versus Brawn: The Changing World of Hydraulic Model Studies), with very good results...but still don't know how the have proceeded.

Do I need more cells?(already 40 000 000), more fixed points, or are there any options of calculation I should use?

Julien

Michael Barkhudarov October 2, 2008 09:14

Re: PK weir simulation? It's very exciting!
 
40 million is a lot more than is usually required. I suspect the mismatch in the flow rate is to do with the boundary conditions are the mesh edges.

Michael

Julien October 2, 2008 09:53

Bcdata in PK weir simulation
 
Hi Michael,

I have also thought about that...I have put specified pressure a the left boundarie, and imposed the fluid height (in stagnation pressure). At the right side, I have set Outflow. In Y direction symmetry condition are set.

Have you got any other idea?

Thanks


michael barkhudarov October 4, 2008 00:15

Re: Bcdata in PK weir simulation
 
Outflow BC may be ok for a supercritical flow. For subcritical, it is better to define pressure with a surface height, otherwise, the problem is not well defined.

Michael

Julien October 6, 2008 02:17

Re: Bcdata in PK weir simulation
 
Thanks a lot. I will try this and then tell you about it!

Julien

Julien October 9, 2008 04:04

Re: Bcdata in PK weir simulation
 
Well thanks a lot Michael, I have already better results for my flowrate trought my PK weir.

Julien


Michael Barkhudarov October 10, 2008 08:59

Re: Bcdata in PK weir simulation
 
Glad to here this, Julien.


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