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-   -   Boundary conditions (http://www.cfd-online.com/Forums/cfx/118757-boundary-conditions.html)

Brainiak June 3, 2013 17:11

Boundary conditions
 
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]

hmasenger June 4, 2013 02:45

I don’t understand your model definition and your approach. (I think nobody knows and that’s why your question is still unanswered ;)!)

oj.bulmer June 4, 2013 04:54

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!! :cool:

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

Brainiak June 4, 2013 13:52

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?

ghorrocks June 5, 2013 06:04

Is it clear? - No, not yet. An image would help.


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