Absolute pressure

meysami · July 18, 2009, 10:17

Hello,

Would you please tell me how can define a absolute pressure in fluid?
because, when I simulate a free surface and define a void pressure in top area, a logical hydrostatic pressure does not form. I am modeling bubble formation on a hot rod, also I active cavitation model.

best regard

stefmascio · July 20, 2009, 11:14

if you are using the gravity, and you set an initial pressure with absolute values, then you'll have in your calculation absolute values of pressures.

meysami · July 21, 2009, 03:55

Dear Stefano
Thank you very much for your answer.
I set gravity and initial pressure with absolute valie, but the pressure was very variable during solving. would you please tell me where are there any mistakes? I must tell you that I have active bubble phase change mode in this calculation

best regards

stefmascio · July 21, 2009, 05:13

hello meysami,
it is hard to understand what happens in your simulation. I would need more informations. But you can start to look in the online manual, at the chapter "How do I model", to check if you are modeling the bubble with all the data needed or if something is missing.

meysami · July 21, 2009, 06:21

Dear Stefano

Thank you very much. For bubble modeling I have checked every thing many times, but unfortunately I have not gotten correct answer and the pressure varies during calculation, I do not understand why pressure is variable, if possible for you I can send my perpin file to you via email. I will very pleasure that you help me for solving this problem. I am waiting your answer

Best regard

stefmascio · July 21, 2009, 06:37

if you use the bubble model then it is right that the pressure changes: it will change following the equation of state of the gas.

July 18, 2009, 10:17	Absolute pressure	#1
meysami New Member amirhossein meysami Join Date: Jul 2009 Posts: 3 Rep Power: 17	Hello, Would you please tell me how can define a absolute pressure in fluid? because, when I simulate a free surface and define a void pressure in top area, a logical hydrostatic pressure does not form. I am modeling bubble formation on a hot rod, also I active cavitation model. best regard

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July 20, 2009, 11:14		#2
stefmascio Member Stefano Join Date: Mar 2009 Posts: 59 Rep Power: 17	if you are using the gravity, and you set an initial pressure with absolute values, then you'll have in your calculation absolute values of pressures.

July 21, 2009, 03:55		#3
meysami New Member amirhossein meysami Join Date: Jul 2009 Posts: 3 Rep Power: 17	Dear Stefano Thank you very much for your answer. I set gravity and initial pressure with absolute valie, but the pressure was very variable during solving. would you please tell me where are there any mistakes? I must tell you that I have active bubble phase change mode in this calculation best regards

July 21, 2009, 05:13		#4
stefmascio Member Stefano Join Date: Mar 2009 Posts: 59 Rep Power: 17	hello meysami, it is hard to understand what happens in your simulation. I would need more informations. But you can start to look in the online manual, at the chapter "How do I model", to check if you are modeling the bubble with all the data needed or if something is missing.

July 21, 2009, 06:21		#5
meysami New Member amirhossein meysami Join Date: Jul 2009 Posts: 3 Rep Power: 17	Dear Stefano Thank you very much. For bubble modeling I have checked every thing many times, but unfortunately I have not gotten correct answer and the pressure varies during calculation, I do not understand why pressure is variable, if possible for you I can send my perpin file to you via email. I will very pleasure that you help me for solving this problem. I am waiting your answer Best regard

July 21, 2009, 06:37		#6
stefmascio Member Stefano Join Date: Mar 2009 Posts: 59 Rep Power: 17	if you use the bubble model then it is right that the pressure changes: it will change following the equation of state of the gas.