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Old   August 18, 2009, 09:22
Default Gravity effect
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Mario Tremblay
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Hi,

I am trying to simulate a return line by gravity. I want to know the maximum flow that can pass trought this line. I modelised the return line. In the two extremity, I put en opening pressure. Than, I set the gravity Y to 9,81m/s^2.

But the result are incoerent. The velocity flow is to low. Maybe I did something wrong. Can you tell me an other way to simulate my return line.

Tanks
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Old   August 18, 2009, 18:14
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Camilo Costa
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Make sure that your reference density is correct!! If your reference density is correct try input a 0 Pa for your reference atmospheric pressure inside your domain!!
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Old   August 19, 2009, 08:45
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Tanks for your answer,

I try to put my reference pressure to 0Pa. I also put boath end of te return line to openning and 0Pa.

The result are still incoerent.

Maybe I did not put my gravity at the wright place.

Actualy à set the Buoyancy to Buoyant. Than I set gravity Y Dirn. to 9.81m/s^2.

Gravity X and Z Dirn. is set to 0.
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Old   August 20, 2009, 15:48
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I try a few other thing, but I still have an incoerent résult. To vérified my analisys, I modelise a srtait pipe so it is easy to compare with hand calculs.

If someone have alerady done the same analysis as my, I would be happy to know how you have done.

Sory for my writing mistake, english is not my first language.

tanks
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Old   August 20, 2009, 16:31
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Camilo Costa
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If you send the yourfile.def for i analyse the problem will be more easy to verify the problem!!

Regards!!
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Old   August 20, 2009, 18:00
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Hi Mario,

if your system is in "normal position", ie, the gravity vector cause a force in the negative Y direction, your component must be defined "Gravity Y=-9.81". Or your can use the variable "g" (recognized as the normal gravity >> "Gravity Y=-g".)
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Old   August 21, 2009, 07:56
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Can I send you my file by e-mail??

If not where I can put my *.def file to give it to you.
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Old   August 21, 2009, 08:13
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Great

I think I found my mistake,

It was the boyancy réference température that was not the wright one. The température was to low.
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Old   August 21, 2009, 09:30
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No nothing!!
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