# Gravity effect

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 August 18, 2009, 09:22 Gravity effect #1 New Member   Mario Tremblay Join Date: Aug 2009 Posts: 14 Rep Power: 9 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

 August 18, 2009, 18:14 #2 Member   Camilo Costa Join Date: Jun 2009 Posts: 34 Rep Power: 9 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!!

 August 19, 2009, 08:45 #3 New Member   Mario Tremblay Join Date: Aug 2009 Posts: 14 Rep Power: 9 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.

 August 20, 2009, 15:48 #4 New Member   Mario Tremblay Join Date: Aug 2009 Posts: 14 Rep Power: 9 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

 August 20, 2009, 16:31 def file #5 Member   Camilo Costa Join Date: Jun 2009 Posts: 34 Rep Power: 9 If you send the yourfile.def for i analyse the problem will be more easy to verify the problem!! Regards!!

 August 20, 2009, 18:00 #6 New Member   BGK Join Date: Aug 2009 Posts: 7 Rep Power: 9 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".)

 August 21, 2009, 07:56 #7 New Member   Mario Tremblay Join Date: Aug 2009 Posts: 14 Rep Power: 9 Can I send you my file by e-mail?? If not where I can put my *.def file to give it to you.

 August 21, 2009, 08:13 #8 New Member   Mario Tremblay Join Date: Aug 2009 Posts: 14 Rep Power: 9 Great I think I found my mistake, It was the boyancy réference température that was not the wright one. The température was to low.

 August 21, 2009, 09:30 #9 Member   Camilo Costa Join Date: Jun 2009 Posts: 34 Rep Power: 9 No nothing!!

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