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

Moment coefficient on moving mesh

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

Reply
 
LinkBack Thread Tools Display Modes
Old   June 19, 2012, 12:08
Default Moment coefficient on moving mesh
  #1
Senior Member
 
Join Date: Apr 2010
Posts: 151
Rep Power: 6
flowris is on a distinguished road
Quick question: I use forces to calculates forces and moments on a moving object. The forces are well calculated, but the moment is not, and I think this is because the center of rotation (CofR) is fixed in system/controlDict:

Code:
functions
{
forces
{
type forces;
functionObjectLibs ( "libforces.so" );
outputControl timeStep;
outputInterval 1;
patches (foil);
pName p;
UName U;
rhoName rhoInf;
log true;
rhoInf 1000;
CofR (0 0 0);
liftDir (0 1 0);
dragDir (1 0 0);
pitchAxis (0 0 1);
magUInf 0.4;
lRef 0.1;
Aref 0.002;
}
I know at any time where this point is (can be seen from the dynamicMeshDict), but can forces change its CofR?
flowris is offline   Reply With Quote

Old   June 19, 2012, 17:15
Default
  #2
Senior Member
 
lore
Join Date: Mar 2010
Location: Italy
Posts: 425
Rep Power: 8
lovecraft22 is on a distinguished road
Send a message via Skype™ to lovecraft22
I don't have much of experience on this but if you know where your CofR is in time, then you can easily evaluate the moment around any other point P:

Mp1 = Mp2 + p2p1 x F

Where:

Mp1 = moment around point p1
Mp2 = moment around point p2
p2p1 = vector going from p2 to p1
F = the force which generates the moment
x = cross product
__________________
I use PowerFLOW!
lovecraft22 is offline   Reply With Quote

Old   June 20, 2012, 01:33
Default
  #3
Senior Member
 
Join Date: Apr 2010
Posts: 151
Rep Power: 6
flowris is on a distinguished road
Brilliant!
flowris is offline   Reply With Quote

Reply

Tags
cofr, forces, moving mesh

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
SnappyHexMesh for internal Flow vishwa OpenFOAM 22 July 14, 2014 19:30
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
Dynamic Mesh moving interface help akash.iitb FLUENT 0 August 23, 2010 23:53
salome, openfoam and moving mesh prhlava OpenFOAM Running, Solving & CFD 8 November 9, 2009 08:59
Moving (structured) mesh Jesper CFX 5 February 2, 2007 03:43


All times are GMT -4. The time now is 03:28.