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#1 |
New Member
Albin Johny
Join Date: Oct 2014
Location: India
Posts: 11
Rep Power: 11 ![]() |
Hello formers
I have been doing an airfoil pitching case in OpenFOAM and I was able to do the pitching from angle 0 to -1. But I have to do a pitching case such that the airfoil starts from 0 to -1 and then to +1 and so on in an oscillatory form. My dynamicMeshDict for 0 to -1 is given below Code:
dynamicFvMesh dynamicMotionSolverFvMesh; motionSolverLibs ("libsixDoFRigidBodyMotion.so"); solver sixDoFRigidBodyMotion; sixDoFRigidBodyMotionCoeffs { patches (wing); innerDistance 0.3; outerDistance 1; mass 60; centreOfMass (0.25 0 0); momentOfInertia (0.09408 0.17475 1.5296); orientation ( 0.999847695 -0.017452406 0 0.017452406 0.999847695 0 0 0 1 ); angularMomentum (0 0 0.25); g (0 -9.81 0); rhoName rhoInf; rhoInf 1; report on; constraints { yLine { sixDoFRigidBodyMotionConstraint line; centreOfRotation (0.25 0 0); direction (0 1 0); } zAxis { sixDoFRigidBodyMotionConstraint axis; axis (0 0 1); } } restraints { verticalSpring { sixDoFRigidBodyMotionRestraint linearSpring; anchor (0.25 0 0); refAttachmentPt (0.25 0 0); stiffness 4000; damping 2; restLength 0; } axialSpring { sixDoFRigidBodyMotionRestraint linearAxialAngularSpring; axis (0 0 1); stiffness 700; damping 0.5; referenceOrientation $orientation; } } } The solver I am using is rhoPimpleDyMFoam. Last edited by wyldckat; June 17, 2015 at 15:37. Reason: Added [CODE][/CODE] markers |
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#2 |
New Member
Albin Johny
Join Date: Oct 2014
Location: India
Posts: 11
Rep Power: 11 ![]() |
I am trying to do an oscillating pitching airfoil in rhoPimpleDyMFoam in subsonic mach. But in my case the oscillation is in the form of 1.02cos(omega*t) but in oscillatingRotatingMotion the rotating motion is given as amplitude*sin(omega*t) and also my rotation is only going in +ve direction and not in -ve direction. Can anyone help me resolve the problem?
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#3 |
New Member
Albin Johny
Join Date: Oct 2014
Location: India
Posts: 11
Rep Power: 11 ![]() |
I am doing a pitching airfoil in rhoPimpleDyMFoam and according to oscillatingRotatingMotion the angle of attack is calculated using "vector eulerAngles = amplitude_*sin(omega_*t)". In my case the pitching should be "amplitude_*cos(omega_*t)". Can anybody suggest how can I solve this problem.
I tried changing in the oscillatingRotatingMotion.C file but it wont work. Please give suggessions? Last edited by albinjohny; June 16, 2015 at 06:07. |
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#4 |
Senior Member
Philippose Rajan
Join Date: Mar 2009
Location: Germany
Posts: 552
Rep Power: 25 ![]() |
Hello there,
A Good Evening to you! I am not sure what you are suggesting can work.... Basically, the oscillatory motion rotates part of the mesh as per the enforced function. In the current implementation, this function is: theta = amplitude * sin(omega * t) I dont think you can change that to: theta = amplitude * cos(omega * t) If you think about it, y = A*cos(w*t) at time t = 0 will give the result y = A. This would imply that at the beginning of you simulation, at time t = 0, you want the mesh to suddenly jump to its maximum position, which does not make sense. The reason why you use y = A*sin(w*t) is because at time t = 0, Y = 0, which means, that the mesh starts at its initial position, and with time slowly moves from this initial position to its maxima (Y = A) and back. Hope this helps clear things up :-) Regards, Philippose |
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#5 |
New Member
Albin Johny
Join Date: Oct 2014
Location: India
Posts: 11
Rep Power: 11 ![]() |
Thank you for the reply
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#6 |
New Member
Milad
Join Date: Feb 2018
Posts: 17
Rep Power: 8 ![]() |
hi everyone
I try to import a mesh from gambit to openfoam. I have inner circle with domain of Rectangular. My boundary condition between circle and rectangular is interface. The openfoam did not accept these boundaries and change it to a default wall. How can i change them? ![]() |
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#7 | |
New Member
Milad
Join Date: Feb 2018
Posts: 17
Rep Power: 8 ![]() |
Quote:
My case in openfoam is exactly same as yours but i use pimpledymfoam alone. I am afraid if it is possible to explain how to import mesh and how to make generate boundaries around airfoil? thank you in advance |
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#8 |
New Member
Chayanit Nigaltia
Join Date: Jan 2018
Posts: 29
Rep Power: 8 ![]() |
Hi everyone
I am simulating a 2d airfoil pitching with some freestream. i am using solidBodyMotion (OscillatingRotatingMotion). I am confused about the parameters origin and amplitude in the dynamicMeshDict. Can anyone tell me how to set this parameters for a 2d airfoil. regards Chayanit |
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#9 |
Senior Member
Join Date: Mar 2018
Posts: 115
Rep Power: 8 ![]() |
@Chayanit
check this link: https://openfoamwiki.net/index.php/P...dyMotionFvMesh origin: The origin of rotation. This will be the rotation point. amplitude: This is the amplitude of the rotating motion. The rotating motion amplitude is provided as a 3D vector definition. The total magnitude of the vector provides the amplitude of the motion. The individual component directions specify the axis of rotating oscillation. Rotation will oscillate about this axis. All component directions oscillate at the same frequency. Motion is defined in units of rad. |
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#10 |
New Member
Chayanit Nigaltia
Join Date: Jan 2018
Posts: 29
Rep Power: 8 ![]() |
Thank you so much.
That means if I want to rotate about z-axis with an angle of 1 rad, I should put amplitude (0 0 1) and if the rotation axis is x=0.25, then I should put origin (0.25 0 0). Am I correct? |
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#11 |
Senior Member
Join Date: Mar 2018
Posts: 115
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Yes, that's correct except that the angles for amplitude are in degrees, not radians. But omega is in rad/s.
Last edited by anon_q; November 16, 2018 at 06:37. |
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#12 |
New Member
Chayanit Nigaltia
Join Date: Jan 2018
Posts: 29
Rep Power: 8 ![]() |
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