# Sinusoidal velocity settings ?

 User Name Remember Me Password
 Register Blogs Members List Search Today's Posts Mark Forums Read

 November 3, 2008, 05:54 Sinusoidal velocity settings ? #1 Adenlan Guest   Posts: n/a Hi everyone, I'm trying to setup a sinusoidal current in cfx but it seems I don't use the proper way. I set the simulation on transient mode in inlet boundary I use a cartesian velocity with expression : U=0 V=0 W=W [m s^-1]*sin(pi[rad s^-1]*t) and initial conditions set to 0 . The problem is that it does not converge instead each iteration I have this message : ****** Notice ****** | A wall has been placed at portion(s) of an OUTLET boundary condition (at 76.5% of the faces, 77.1% of the area)to prevent fluid from flowing into the domain. The boundary condition name is: outlet.The fluid name is: Water. If this situation persists, consider switching to an Opening type boundary condition instead. Please someone help me !

 November 3, 2008, 06:12 Re: Sinusoidal velocity settings ? #2 Adenlan Guest   Posts: n/a Don't mind, my error is too obvious

 November 4, 2008, 07:47 Re: Sinusoidal velocity settings ? #3 underGroundMan Guest   Posts: n/a Set your outlet to 1 atm and reference pressure to zero.

 November 6, 2008, 13:13 Re: Sinusoidal velocity settings ? #4 Amod Guest   Posts: n/a By definition, Inlet Boundary condition should have flow always into the domain and Outlet Boundary condition should have flow always out of the domain. By specifying inlet velocity profile as a function of time, you are changing the magnitude and direction of flow at the inlet boundary. This is not acceptable mathematically! You may have to use moving boundary problem such as movement of Piston in an internal combustion engine. Hope it clears! Amod

 November 7, 2008, 04:49 Re: Sinusoidal velocity settings ? #5 Rui Guest   Posts: n/a Hi, Why is it not acceptable mathematically? What happens when one defines a negative (outwards) velocity on an Inlet Boundary in CFX? P.S. There's nothing wrong in changing the magnitude of the flow at an Inlet Boundary, is there?

 November 12, 2008, 07:02 Re: Sinusoidal velocity settings ? #6 underGroundMan Guest   Posts: n/a I agree Rui. I have used time varying boundary condition many times and it works fine.

 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 Zaqie Fluent UDF and Scheme Programming 8 May 11, 2014 08:34 spk Main CFD Forum 3 July 9, 2010 08:42 Kali Sanjay Phoenics 1 May 1, 2006 13:57 Antech Main CFD Forum 0 April 25, 2006 02:15 Abhi Main CFD Forum 12 July 8, 2002 09:11

All times are GMT -4. The time now is 17:31.

 Contact Us - CFD Online - Top