# Boundary conditions

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 June 3, 2013, 17:11 Boundary conditions #1 New Member   e Join Date: Jun 2013 Posts: 3 Rep Power: 4 Hello everyone! Could anybody help me what should I put on a ballon-car (gondola) as a boundary conditions. I have a active disc area and (this is all in 3d) there should be a propeller, but for fisrt resolution I have to calculate without fan - just an active disc. I've tried to put in Inlet&Outlet velocity, mass flow, pressure - overflow (Error!!) anyway - Mach number->100000... Mesh has a good quality - the problem is in boundary conditions or smth else. Who solves smth like this HELP! SST-model, step is a really small (doesn't help too). Maybe I don't know smth, let me know.[/IMG http://i031.radikal.ru/1306/cf/1e9ee99f25ba.jpg] Last edited by Brainiak; June 3, 2013 at 17:22. Reason: propeller

 June 4, 2013, 02:45 #2 Senior Member     hamed Join Date: Apr 2009 Posts: 148 Rep Power: 8 I don’t understand your model definition and your approach. (I think nobody knows and that’s why your question is still unanswered !)

June 4, 2013, 04:54
#3
Senior Member

OJ
Join Date: Apr 2012
Location: United Kindom
Posts: 475
Rep Power: 11
Quote:
 Mach number->100000
Does your balloon travels in the air at 11% the speed of light?? That makes even Voyager space craft travelling through intergalactic vacuum look like a snail!!

Jokes aside, like hamed says, more details (explained lucidly) about your BCs and problem definition can help you get more help in the forum

OJ

 June 4, 2013, 13:52 #4 New Member   e Join Date: Jun 2013 Posts: 3 Rep Power: 4 It's a gondola in ideal gas, ok? I have pressurein DOMAIN, velocity_x and Temperature in inlet, and difference in pressure in outlet. In inlet_disc I've tried to put velocity as in outlet_disc, but it doesn't work. How to set conditions to solve this? It's clear?

 June 5, 2013, 06:04 #5 Super Moderator   Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 10,665 Rep Power: 84 Is it clear? - No, not yet. An image would help.

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