Compressible flow boundary conditions

AnaE · October 23, 2015, 07:36

Hi,

I am trying to analyse the behavior of the engine exhaust gas in a structural facility, with wind conditions.

For the effect I am using compressible flow, but I am having trouble in the boundary conditions in the volume of control. I was thinking about velocity inlet and pressure outlet, however that is not valid for compressible. I have tried pressure inlet and pressure outlet, and mass flow inlet and pressure outlet however nothing is working very well.

Any suggestions?

Thank you

LuckyTran · October 24, 2015, 15:02

A pressure inlet and pressure outlet pair are generally the most robust. For compressible flows you'll have to specify the inlet stagnation pressure (& stagnation temperature). If you need a particular mass-flow rate then use the target mass flow rate option on the pressure outlet. If this doesn't work, then you're probably doing something wrong.

AnaE · October 26, 2015, 08:01

This issue is - I do have convergence, but the problem is symmetrical and I am obtaining asymmetric results for the airflow. That only happens in 2nd order. I am using pressure standard and the results are getting better, but I don't understand the reason behind it.

RodriguezFatz · October 28, 2015, 10:09

Can you post some pictures?

October 23, 2015, 07:36	Compressible flow boundary conditions	#1
AnaE New Member Join Date: Oct 2015 Posts: 5 Rep Power: 12	Hi, I am trying to analyse the behavior of the engine exhaust gas in a structural facility, with wind conditions. For the effect I am using compressible flow, but I am having trouble in the boundary conditions in the volume of control. I was thinking about velocity inlet and pressure outlet, however that is not valid for compressible. I have tried pressure inlet and pressure outlet, and mass flow inlet and pressure outlet however nothing is working very well. Any suggestions? Thank you

October 28, 2015, 10:09		#4
RodriguezFatz Senior Member Philipp Join Date: Jun 2011 Location: Germany Posts: 1,297 Rep Power: 28	Can you post some pictures? __________________ The skeleton ran out of shampoo in the shower.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Wind turbine simulation	Saturn	CFX	60	July 17, 2024 06:45
Overflow Error in Multiphase Modelling with Two Continuous Fluids	ashtonJ	CFX	6	August 11, 2014 15:32
Radiation interface	hinca	CFX	15	January 26, 2014 18:11
Boundary conditions for compressible flow	cici	Main CFD Forum	1	April 29, 2013 02:03
compressible flow boundary conditions	yangqing	FLUENT	2	January 22, 2002 11:19

October 24, 2015, 15:02		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,837 Rep Power: 68	A pressure inlet and pressure outlet pair are generally the most robust. For compressible flows you'll have to specify the inlet stagnation pressure (& stagnation temperature). If you need a particular mass-flow rate then use the target mass flow rate option on the pressure outlet. If this doesn't work, then you're probably doing something wrong.

October 26, 2015, 08:01		#3
AnaE New Member Join Date: Oct 2015 Posts: 5 Rep Power: 12	This issue is - I do have convergence, but the problem is symmetrical and I am obtaining asymmetric results for the airflow. That only happens in 2nd order. I am using pressure standard and the results are getting better, but I don't understand the reason behind it.