CFD Online Logo CFD Online URL
Home > Forums > Main CFD Forum

Inlet / Outlet boundary condition? (CFX, but also general CFD)

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

LinkBack Thread Tools Display Modes
Old   June 30, 2010, 08:52
Default Inlet / Outlet boundary condition? (CFX, but also general CFD)
New Member
adrijana radosevic
Join Date: Dec 2009
Posts: 7
Rep Power: 7
TurbulentFluid is on a distinguished road
I have a situation where water flows into a pipe for a given period of time, and then flows out of it for a different period of time (a "can" is first filled, then emptied through the same pipe). The flow regime can be:
- governed by a function, let's say f(t) = sin(0.3*t).
- governed by an if statement, eg. if(t<2[s],1[m/s],-1[m/s])

I have tried setting this function at an inlet boundary condition.
I do get the inflow for the inflow part of the interval correctly, however the water does not exit through the inlet BC during the outflow interval. The inlet BC seems to treat all the negative velocity or mass flow values as 0, whether I define them as "Normal to boundary" or by the coordinates.

How do I solve this problem? Is there a possibility to change the BC during the simulation time by the means of an expression (eg, if(t<2[s],INLET,OUTLET)? Or is there a workaround that will allow me to "pour out" the fluid through the inlet?

I am using Ansys CFX, but I also have access to other softwares (FLUENT, OpenFlow, Comsol...). Any advice would be much appreciated!
TurbulentFluid is offline   Reply With Quote


boundary conditions, cfx, inflow/outflow

Thread Tools
Display Modes

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 Off
Trackbacks are On
Pingbacks are On
Refbacks are On

Similar Threads
Thread Thread Starter Forum Replies Last Post
outlet boundary condition for compressor modeling siamak1424 FLUENT 3 August 8, 2009 05:55
Outlet boundary condition for pd in InterFoam gopala OpenFOAM Running, Solving & CFD 0 March 19, 2008 10:26
Outlet boundary condition Asghari Main CFD Forum 0 May 5, 2006 16:51
New topic on same subject - Flow around race car Tudor Miron CFX 15 April 2, 2004 06:18
what the result is negatif pressure at inlet chong chee nan FLUENT 0 December 29, 2001 06:13

All times are GMT -4. The time now is 13:52.