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-   -   How simulate the aerated flow in spillway using Flow-3D (http://www.cfd-online.com/Forums/flow-3d/115716-how-simulate-aerated-flow-spillway-using-flow-3d.html)

Zenvironment April 5, 2013 07:43

How simulate the aerated flow in spillway using Flow-3D
 
3 Attachment(s)
Recently,we are simulating the aerated flow in spillway by using Flow-3D, but I have some questions about the models and parameters in the simulation.
Jeff Burnham has said this situation only need three models: air entrainment、density evaluation and drift-flux. I think so, but I can not get the parameters from everywhere.
Who can tell me how define the parameters ?Aeration concentration is very important for me. I will be very happy if you could give me the more details.
My research project planning is about ordinary spillway (Non-stepped). Can you give some advices ?
If you can help me, I would be very grateful !
Attachment 20468

Attachment 20469

Attachment 20470

flow_CH April 6, 2013 04:54

HI
do you simulating a spillway with self aeration or artificial aeration into the aerator ramp? because I have same problem.But i could not access a good guide to simulate that.
i don't know can i simulate spillway with aerator device in flow 3d or fluent?

JBurnham April 6, 2013 22:54

Those parameters look reasonable. The one that might need calibration is the Air Entrainment Rate Coefficient: it is very cell-size dependent in FLOW-3D versions before v10.1.

The best way to approach it would be to find data for a case that is similar in scale to the one you are going to model. Find the mesh size that you want to use for your case, and with that mesh size, do simple test cases to figure out what the air entrainment rate coefficient should be.

If you have no idea, use 0.5, but the concentration may not be as accurate as you would like. The trend will be correct, and usually depth-of-penetration of the air is pretty reliable as well.

Zenvironment April 8, 2013 22:30

my project is also about aerator device . The documents what I have read almost simulate the solution by Fluent. But my tutor make me use the Flow-3D, I have no idea. How about your project?

Zenvironment April 8, 2013 22:34

Quote:

Originally Posted by flow_CH (Post 418710)
HI
do you simulating a spillway with self aeration or artificial aeration into the aerator ramp? because I have same problem.But i could not access a good guide to simulate that.
i don't know can i simulate spillway with aerator device in flow 3d or fluent?

my project is also about aerator device . The documents what I have read almost simulate the solution by Fluent. But my tutor make me use the Flow-3D, I have no idea. How about your project?

Zenvironment April 8, 2013 22:51

Quote:

Originally Posted by JBurnham (Post 418823)
Those parameters look reasonable. The one that might need calibration is the Air Entrainment Rate Coefficient: it is very cell-size dependent in FLOW-3D versions before v10.1.

The best way to approach it would be to find data for a case that is similar in scale to the one you are going to model. Find the mesh size that you want to use for your case, and with that mesh size, do simple test cases to figure out what the air entrainment rate coefficient should be.

If you have no idea, use 0.5, but the concentration may not be as accurate as you would like. The trend will be correct, and usually depth-of-penetration of the air is pretty reliable as well.

Thank you very much,JBurnham. I think you must be an expert, I read all your replies in the forums. Now we are simulating the spillway on the basis of your idea.
If you have time, can you tell me about the Richard-Zaki coefficient mutiplierAverage particle radius and Volume fraction of phase #2atinversion point in the Drift-flux model.
Thank you !

flow_CH April 9, 2013 07:50

Quote:

Originally Posted by Zenvironment (Post 419256)
my project is also about aerator device . The documents what I have read almost simulate the solution by Fluent. But my tutor make me use the Flow-3D, I have no idea. How about your project?

can you simulate this project in flow3d? if you can then i can do that too.
my problem is injecting air into the air duct. can you simulate that? and can flow3d model the cavity above the offset?
is your project similar to this pic?
see this pic

Zenvironment April 10, 2013 22:25

2 Attachment(s)
Quote:

Originally Posted by flow_CH (Post 419386)
can you simulate this project in flow3d? if you can then i can do that too.
my problem is injecting air into the air duct. can you simulate that? and can flow3d model the cavity above the offset?
is your project similar to this pic?
see this pic

It's so similar。 In fact, I have given my results to my teacher, he said the result is almost correct, but I must prove the method is right. Our hydraulic model can not get the data of air concentration, so I need to prove my method by myself.
Attachment 20648

Attachment 20649

flow_CH April 10, 2013 23:59

1 Attachment(s)
Quote:

Originally Posted by Zenvironment (Post 419760)
It's so similar。 In fact, I have given my results to my teacher, he said the result is almost correct, but I must prove the method is right. Our hydraulic model can not get the data of air concentration, so I need to prove my method by myself.
Attachment 20648

Attachment 20649

Thanks. Can you give me the prepin file of your project.I don't know which software can simulate this situation (flow3d or fluent). I want to know can flow3d simulate the cavity bottom of the offset? with Increasing or decreasing the air rate into the ramp.


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