PKweir with Flow-3D 9.3

October 2, 2008, 04:56

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

October 2, 2008, 05:46

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!

October 2, 2008, 06:20

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

October 2, 2008, 10:14

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

October 2, 2008, 10:53

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

October 4, 2008, 01:15

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

October 6, 2008, 03:17

Thanks a lot. I will try this and then tell you about it!

Julien

October 9, 2008, 05:04

Well thanks a lot Michael, I have already better results for my flowrate trought my PK weir.

Julien

October 10, 2008, 09:59

Glad to here this, Julien.

October 2, 2008, 04:56	PKweir with Flow-3D 9.3	#1
Julien Guest Posts: n/a	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

October 2, 2008, 05:46	PK weir simulation? It's very exciting!	#2
Byongjun Park Guest Posts: n/a	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!

October 2, 2008, 06:20	Re: PK weir simulation? It's very exciting!	#3
Julien Guest Posts: n/a	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

October 2, 2008, 10:14	Re: PK weir simulation? It's very exciting!	#4
Michael Barkhudarov Guest Posts: n/a	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

October 2, 2008, 10:53	Bcdata in PK weir simulation	#5
Julien Guest Posts: n/a	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

October 4, 2008, 01:15	Re: Bcdata in PK weir simulation	#6
michael barkhudarov Guest Posts: n/a	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

October 6, 2008, 03:17	Re: Bcdata in PK weir simulation	#7
Julien Guest Posts: n/a	Thanks a lot. I will try this and then tell you about it! Julien

October 9, 2008, 05:04	Re: Bcdata in PK weir simulation	#8
Julien Guest Posts: n/a	Well thanks a lot Michael, I have already better results for my flowrate trought my PK weir. Julien

October 10, 2008, 09:59	Re: Bcdata in PK weir simulation	#9
Michael Barkhudarov Guest Posts: n/a	Glad to here this, Julien.

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