# How to simulate valve with pressure BC?

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 June 20, 2006, 01:27 How to simulate valve with pressure BC? #1 Luk Guest   Posts: n/a Hi all, I have following problem. The geometry is very simple: air enters the pipe from one side under pressure. On the other side there is valve: the valve could be in one of two positions: "closed" where no flow is possible (pipe closed from one side) and "opened" where sucking occurs through the valve. The valve opens and closes periodicaly. I am using UDF to represent changes of the valve state in time but I dont know how to simulated closed valve with pressure BC. Any ideas? Luk

 June 20, 2006, 02:31 Re: How to simulate valve with pressure BC? #2 Gernot Guest   Posts: n/a Why donīt you change your pressure outlet to wall and backwards ?

 June 20, 2006, 03:46 Re: How to simulate valve with pressure BC? #3 Luk Guest   Posts: n/a Is it possible with UDF? I mean is it possible to periodicaly change type of BC for specified surface/face?

 June 20, 2006, 04:47 Re: How to simulate valve with pressure BC? #4 Gernot Guest   Posts: n/a I didnīt work much with UDFīs. But Iīm sure you can handle that with a journal file. The question is how often do you open and close?

 June 20, 2006, 06:12 Re: How to simulate valve with pressure BC? #5 Luk Guest   Posts: n/a About 100/sec. The size of the pipe is few cm in diameter and about 50cm length. Pressures are rather low.

 June 20, 2006, 06:46 Re: How to simulate valve with pressure BC? #6 Gernot Guest   Posts: n/a O.K., i tried some things. To change the boundary condition with a journal file is possible. To start the journal file with an execute-comand works too. So there is a posibility to automate the whole thing but itīs a long way. Maybe someone else knows an alternative.

 June 20, 2006, 07:07 Re: How to simulate valve with pressure BC? #7 Luk Guest   Posts: n/a Dear Sir, Thanks for Your kind help! I'll try this solution today in few hours. Luk

 June 20, 2006, 07:25 Re: How to simulate valve with pressure BC? #8 Gernot Guest   Posts: n/a last chance for me to help you is tomorrow, then Iīm on holiday for 2 weeks - Jippie!!!! The execute comand to start the journal is easy : file read-journal nameofjournal the journal comands to switch from wall to pressure outlet : define boundary-condition modify-zones zone-type ( ID number of your face you want to switch ) pressure-outlet ( or wall when you switch back ) but be careful the settings of your pressure outlet are set to the default values. you can change them with : define boundary-condition pressure-outlet good luck

 June 20, 2006, 08:06 Re: How to simulate valve with pressure BC? #9 Luk Guest   Posts: n/a I wish Your nice holydays! Could You be so kind and send me email for further contact: my address is Lukasz.Czopyk@ifj.edu.pl. I promise not to disturb Your free time anyway. Luk

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