CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > OpenFOAM Programming & Development

OpenFOAM Variable Velocity Boundary Conditions

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

Reply
 
LinkBack Thread Tools Display Modes
Old   May 18, 2011, 10:31
Exclamation OpenFOAM Variable Velocity Boundary Conditions
  #1
Member
 
Nickolas P
Join Date: Oct 2010
Location: Greece
Posts: 30
Rep Power: 6
NickolasPl is on a distinguished road
Hello everybody,

I m kind of new to the OpenFOAM package but I try to learn as much as I can and have run half a dozen of cases with simple geometries and boundary conditions. Actually, I would like to ask if anybody can give me some info on how to implement boundary conditions (especially the velocity) that vary acoording to the geometry of the mesh.

Actually, I study the flow region between two cylindrical rollers to a very close distance each other (actually a few mm). I understand the concept of declaring the patches of the generated mesh as well as the boundary conditions for P and U files. For this problem, however, the velocity boundary condition that belong to the declared patches of the surface of the cylinders varies as the tangential velocity of the cylinders changers direction as they roll. In the U file the boundary condition can be declared as I see by: (ux, uy, uz). In my problem, the tangential velocity, say V is: V = SQRT (ux^2+uy^2). At the circumference of the cylinders the V vector is always the same regarding its "meter", but changes direction due to the different values of ux and uy as we move along the circumference. My question is how that different values of ux and uy that change from position to position of the cylinder's circumference can be implemented as velocity boundary conditions of the declared patches (actually for only a part of the surface of the cylinders).
Any help would be greatly appreciated. Thanks a lot in advance.

Nickolas
NickolasPl is offline   Reply With Quote

Old   May 19, 2011, 03:18
Smile rotating Wall
  #2
New Member
 
mohsen cheraghi
Join Date: Jun 2010
Location: Switzerland
Posts: 26
Rep Power: 7
mohsen cheraghi is on a distinguished road
Hi
You can try rotatingWallVelocity boundary condition. I used it for a cylinder and it works.
good luck
mohsen cheraghi is offline   Reply With Quote

Old   May 19, 2011, 05:37
Default
  #3
Member
 
Nickolas P
Join Date: Oct 2010
Location: Greece
Posts: 30
Rep Power: 6
NickolasPl is on a distinguished road
Hello,

Yes, thanks for your help. I found the following last night and implement it and actually works fine!

type rotatingWallVelocity;
origin (0 0.2 0);
axis (0 0 1);
omega 10;
NickolasPl is offline   Reply With Quote

Reply

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
Some Problems about the Boundary Conditions in OpenFoam lzgwhy OpenFOAM Running, Solving & CFD 13 July 8, 2014 06:17
Boundary Conditions : Total Pressure or Velocity Gearb0x OpenFOAM Running, Solving & CFD 2 February 28, 2011 22:18
New topic on same subject - Flow around race car Tudor Miron CFX 15 April 2, 2004 06:18
Please help with flow around car modelling! Tudor Miron CFX 17 March 19, 2004 20:23
Replace periodic by inlet-outlet pair lego CFX 3 November 5, 2002 21:09


All times are GMT -4. The time now is 03:21.