CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > OpenFOAM > OpenFOAM Running, Solving & CFD

6-DoF Rigid Body Motion

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 7, 2015, 17:58
Default 6-DoF Rigid Body Motion
  #1
New Member
 
Gianpaolo
Join Date: Jan 2015
Posts: 4
Rep Power: 11
jumpa72 is on a distinguished road
Hi, I'm running a simulation of a cross-flow turbine, with interDyMFoam.
I've modeled the rotor with the 6-dof rigid body motion. The simulation is running fine, but I've a problem.
The rotor is spinning aroung Z-axis.
Here is the dynamicMeshDict

Code:
sixDoFRigidBodyMotionCoeffs 
{ 
    patches         (pala); 
    innerDistance   1e5; // Extent of the solid-body motion region around body 
    outerDistance   1.1e5; // Extent of mesh-morphing region around body 

    centreOfMass    (0 0 0); 
    mass            2; 
    momentOfInertia (0.06 0.06 0.005); 
        orientation
        (
            1 0 0
            0 1 0
            0 0 1
        );
    velocity        (0 0 0);
    acceleration    (0 0 0);
    angularMomentum (0 0 0);

//    torque  (0 0 666)
    report          on; 
    accelerationRelaxation 0.3; 
    value           uniform (0 0 0); 

    constraints 
    { 
        zAxis 
        { 
            sixDoFRigidBodyMotionConstraint axis; 
            axis          (0 0 1); 
        }
    fixedPt
    {
        sixDoFRigidBodyMotionConstraint point;
         point    (0 0 0);
    }
         
    } 

    restraints
    {
        rotationDamper
        {
           sixDoFRigidBodyMotionRestraint sphericalAngularDamper;
           coeff         0.1;
        }
    }

}
If the torque parameter is commented, in the mesh.update phase of the solution I've reported the 6-dof parameter update, including the angular velocity:
Code:
Restraint rotationDamper:  moment (-0 -0 23.903004)
6-DoF rigid body motion
    Centre of rotation: (0 0 0)
    Centre of mass: (0 0 0)
    Orientation: (0.70693806 -0.70727546 0 0.70727546 0.70693806 0 0 0 1)
    Linear velocity: (0 0 0)
    Angular velocity: (0 0 -239.03019)
AMI: Creating addressing and weights between 4156 source faces and 1904 target faces
AMI: Patch source sum(weights) min/max/average = 0.91803358, 1.004191, 1.0000864
AMI: Patch target sum(weights) min/max/average = 0.80581278, 1.0025247, 0.99988022
Execution time for mesh.update() = 0.58 s
smoothSolver:  Solving for alpha.water, Initial residual = 0.00032745617, Final residual = 8.2593505e-10, No Iterations 3
Phase-1 volume fraction = 0.5470669  Min(alpha1) = 0  Max(alpha1) = 1.0104109
MULES: Correcting alpha.water
MULES: Correcting alpha.water
Phase-1 volume fraction = 0.54706693  Min(alpha1) = -0.0002051717  Max(alpha1) = 1.0104109
smoothSolver:  Solving for Ux, Initial residual = 0.00030591356, Final residual = 6.5264777e-07, No Iterations 2
smoothSolver:  Solving for Uy, Initial residual = 0.00011866999, Final residual = 2.7919284e-07, No Iterations 2
GAMG:  Solving for p_rgh, Initial residual = 0.00066497002, Final residual = 3.3393962e-05, No Iterations 2
time step continuity errors : sum local = 4.3662479e-08, global = -7.3058715e-10, cumulative = -0.00011849602
...
If the torque parameter is given, then I have no data of 6-dof parameter:
Code:
AMI: Creating addressing and weights between 4156 source faces and 1904 target faces
AMI: Patch source sum(weights) min/max/average = 0.65915578, 1.0035944, 0.99996507
AMI: Patch target sum(weights) min/max/average = 0.75657687, 1.0023823, 0.9998494
Execution time for mesh.update() = 0.57 s
smoothSolver:  Solving for alpha.water, Initial residual = 0.00034930917, Final residual = 1.1702469e-09, No Iterations 3
Phase-1 volume fraction = 0.54706979  Min(alpha1) = 0  Max(alpha1) = 1.0104363
MULES: Correcting alpha.water
MULES: Correcting alpha.water
...
My question is, is there a method to get the angular velocity of a 6-dof moving mesh?
tnx in advance
Gianpaolo
jumpa72 is offline   Reply With Quote

Old   June 8, 2015, 10:12
Default
  #2
Senior Member
 
Tom Fahner
Join Date: Mar 2009
Location: Breda, Netherlands
Posts: 638
Rep Power: 32
tomf will become famous soon enoughtomf will become famous soon enough
Send a message via MSN to tomf Send a message via Skype™ to tomf
Hi Gianpaolo,

I am guessing that it is caused by this:

In your commented block there is no closing semicolon on your "torque line". Since you have commented this line there is no problem, however if you uncomment the line, the line is not closed, so OpenFOAM will not read the next line, which specifies that it must report (to the log).

Hope this helps,

Regards,
Tom
tomf is offline   Reply With Quote

Old   June 8, 2015, 11:08
Default
  #3
New Member
 
Gianpaolo
Join Date: Jan 2015
Posts: 4
Rep Power: 11
jumpa72 is on a distinguished road
yes!
Thank you Tom, that's the problem!

Another question:
is there any detailed description of the six dof parameter?
I've found only the brief description in the .H file of six dof body motion...

tnx
Gianpaolo
jumpa72 is offline   Reply With Quote

Old   June 8, 2015, 11:29
Default
  #4
Senior Member
 
Tom Fahner
Join Date: Mar 2009
Location: Breda, Netherlands
Posts: 638
Rep Power: 32
tomf will become famous soon enoughtomf will become famous soon enough
Send a message via MSN to tomf Send a message via Skype™ to tomf
Hi,

I do not think there is something like that available from OpenFOAM directly, maybe you can find something by googling it, if someone has started to analyse it and make it available. I also do not know that much more about the particular library, just spotted the error since I made it myself so many times (in other applications) as well.

Regards,
Tom
tomf is offline   Reply With Quote

Old   March 15, 2021, 08:15
Default restraints
  #5
Member
 
Deutschland
Join Date: Sep 2020
Posts: 69
Rep Power: 5
vava10 is on a distinguished road
hey,

How is the restraints coefficients determined?

vava10 is offline   Reply With Quote

Old   June 2, 2021, 04:48
Default
  #6
Member
 
Himanshu
Join Date: Jan 2017
Posts: 34
Rep Power: 9
Himanshu_Shrivastava is on a distinguished road
Hello,
I am running simulation for kalpan turbine with 6DOF, but the angular velocity keep on increasing.
Does that happen with your simulation?
Himanshu_Shrivastava is offline   Reply With Quote

Old   March 1, 2024, 02:38
Default
  #7
@ss
New Member
 
shristi
Join Date: Jun 2023
Posts: 24
Rep Power: 2
@ss is on a distinguished road
Hello,
I also want to know how the 6dof rigid body motion equation is written in openFoam directly
@ss is offline   Reply With Quote

Reply

Tags
6-dof rigid motion

Thread Tools Search this Thread
Search this Thread:

Advanced Search
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 Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
trying to write a UDF for rigid body motion niteshrajput Fluent UDF and Scheme Programming 4 December 17, 2014 00:29
Rigid body motion on transient fluent mrf ghost82 EnSight 4 September 6, 2014 11:24
Moving mesh Niklas Wikstrom (Wikstrom) OpenFOAM Running, Solving & CFD 122 June 15, 2014 06:20
Force can not converge colopolo CFX 13 October 4, 2011 22:03
rigid body motion antonello FLUENT 3 July 28, 2004 03:25


All times are GMT -4. The time now is 23:35.