# Boundary conditions in CFX-Pre

 Register Blogs Members List Search Today's Posts Mark Forums Read

 February 9, 2005, 14:14 Boundary conditions in CFX-Pre #1 Saikat Guest   Posts: n/a This condition is to simulate room air flow, when an airlock is maintained between two rooms. Let us say we have two rooms one with higher pressure and one with lower pressure. The one with lower pressure has an extract, and one with higher one has inlet (obvious but still I prefer to describe it fully). The two rooms are joined by a small window (filter) which lets some airflow through it so that the pressure differential is maintained for the two rooms. Also there is a door connecting the two rooms which is closed at time t=0. Now when the door is closed all the air has to pass through this filter from the HP room to the LP room. How to define the boundary conditions for this filter? I defined both the rooms to be different domains and then the filter acts as the third domain, joining the two. But the boundary conditions for two sides of the filter (each side connecting to a room respectively) I cannot clearly define yet. I know that, it has to take care that the pressure differential remains maintained, as also one has to consider when the door will eventually open in later stages of calculation, the air flow through the filter decreases since then the door opened takes care of the airflow required. But then the pressure differential is goofed up as well. But as soon as the door is closed again, the filter action would bring back the normal condition in some time. I thought that one may be tempted to say that forget all different domains, just make one domain and let the program decide how it wants to flow. But then I want to have a calculation which gives me the pressure differential calculated in transient flow across this filter. So want time dependent values of pressure across it, when the door is opened and closed again. Is there someway in which I can tell CFX I want delP across the filter to be ## value, when the door is closed, but then when the door is opened how to make the filter realise this and reduce airflow through it?? Help would be appreciated. Thanks

 February 9, 2005, 17:37 Re: Boundary conditions in CFX-Pre #2 Glenn Horrocks Guest   Posts: n/a Hi, For the filter have a look in the documentation for momentum sources and sinks. There are a number of different mechanisms available for modelling flow resistance. Glenn Horrocks

 February 10, 2005, 08:22 Re: Boundary conditions in CFX-Pre #3 Saikat Guest   Posts: n/a Glenn, Thanks a lot. I also came to the same solution looking through the tutorials etc, teaches me, I have to research more before putting up a problem here. Regards Saikat

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Shafiul CFX 10 February 17, 2011 08:57 vaina74 Open Source Meshers: Gmsh, Netgen, CGNS, ... 2 May 27, 2010 09:38 Ardalan Main CFD Forum 6 April 17, 2010 23:40 Young CFX 5 October 6, 2008 23:17 Alexxx CFX 3 November 17, 2006 02:28

All times are GMT -4. The time now is 18:19.