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Richard May 8, 2007 15:51

Open Channel Flow
Does anyone know where I can get a tutorial modeling open channel flow ? Thanks

opaque May 8, 2007 16:19

Re: Open Channel Flow
Dear Richard.,

What is wrong with Tutorial 7 "Free surface flow over a bump"?

It is an open channel flow problem..


Bak_Flow May 8, 2007 20:22

Re: Open Channel Flow
Hi Opaque,

well say a guy had a real problem that is NOT:

1) 2D 2) steady state 3) easy to mesh and determine the reasonable location of inlet and outlet boundary conditions 4) has no published results..

Then would your answer be the looks like you know the numerics of the solver but not the applications?

Can someone out there in CFX figure out that not all of us are doing 2-D problems. I recently was approached by CFX regarging some well documented turbulent heat transfer validations (all demonstrating the advantages of the SST model....that is another issue)....I asked...if there was anything new from a few years ago when all of the cases were 2-D...the answer was .....NO?

Ok I agree that a wonderful way to develop expertise with meshing, numerics, solver settings, etc is with 2D problems but the average user out there pays lost of money to solve real problems....3D, transient, etc....impress us for the $$$$$$$ OK



Opaque May 8, 2007 21:27

Re: Open Channel Flow
Dear Bak_Flow,

Let me review what Richard asked again, perhaps I missed something.

"Does anyone know where I can get a tutorial modeling open channel flow ? Thanks "

and from there anybody (even you) can see that:

0 - He did not specify what research he did on what is available within the package. From his information: None. Otherwise, he would have posed a more specific question.

1 - Did he say 2D, or 3D? No.. Why 2D? Run quickly, so users can move to the next example..

2 - Did he mentioned steady, or transient? No again.

3 - Any mention of complexity of his geometry, or problem.. Not again..

4 - Not published results? Valid point, but tutorials mostly illustrate how to setup the problems. Will a validation of the flow around a Wigley hull be sufficient as a tutorial for free surface flow?

Still.. I do not see anything wrong about starting with tutorial 7. Then, build his problem from there..

Your answer is half constructive (thanks for contributing), and the other half venting out about CFX (sorry if you have been hurt/insulted somehow)

Hopefully Richard can start with Tutorial 7, and then realize how important the points you mention are. Otherwise, he will continue waiting.



Bak_Flow May 10, 2007 01:00

Re: Open Channel Flow
Opaque...possibly I am missing something?

You say "what is wrong with Tutorial 7"

I then list a few things which (even you) can see the tutorial does not cover...don't take offence...I was giving feedback??????

it is weak actually so weak as to demonstrate the inapplicability of the 1 element thick approach to 2-D problems where adaption at the interface results in a fully 3-D adapted mesh????

No CFX never offended or hurt me but thanks for the concern....I just feel we pay loads for commercial software and tutorials that do not fully demonstrate the capabilities are less than we expect....and for that matter...ohh this is going to go to your CFX head....the VOF capability in CFX is actually very good compared to other codes....showing how to use it is not...

No offence intended.....ta.......Bak_Flow

Richard May 10, 2007 17:29

Re: Open Channel Flow
Thank you guys. Actually, my problem is 3D. I need to solve a model of an artificial channel for fish passage way (that is right !) the current must be right (velocity, temp etc) for an endangered species to navigate. The inlet will fairly defined ditto the out let, it will be transient analysis. Any help will be appreciated. Thanks

Gert-Jan May 10, 2007 18:45

Re: Open Channel Flow
What make it transient? Why do you need to model temperature? Do you have a powerplant upstream from which you want to miss the cooling water?


richard May 13, 2007 21:31

Re: Open Channel Flow
Gert-Jan The depth of water will vary with time, the temperature will change depending on the season, and from the dam upstream.

Bak_Flow May 17, 2007 01:14

Re: Open Channel Flow
Hi Richard,

it sounds like and interesting and complex problem as I suspected. Is this something like a Denil Fishway? I understand why the problem is fully 3D.

What scale of the transient are you interesting in modeling? One of the issues with fish is that although they are not a massless particle they are small relative to the scales of the motion and can be affected by the scales of turbulence so one has to either resolve thie motion and how it affects the "particle" or have a good model for how these "particles" are affected by turbulence. Is this where the unsteadyness comes in?

i am curious to find out more.



Sachin Patil May 31, 2007 19:57

Re: Open Channel Flow
Can I get source for the tutorial of open channel flow? I am looking for flow in river and two dimensional flow. I would highly appreciate that.

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