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animation vieweing from different reference frame

Posted Feb 6, 2012, 7:43 a.m. EST Fluid & Heat, Computational Fluid Dynamics (CFD) Version 4.2a 14 Replies

Siva Kumar Manickam
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Hi.
I have used 2d spf cfd flow simulation. I have solved and found velocity of a moving wall BC. Is it possible to change this body-fitted movies/animations to view through other frame?
I mean I solved simulations from boat and I want to see the solution from water. Is that possible?
Thanks in advance
Siva
14 Replies Last Post Feb 27, 2012, 1:10 a.m. EST
Siva Kumar Manickam
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Posted: 1 decade ago Feb 6, 2012, 8:46 p.m. EST
I could see in the animation setting various frames like: material, mesh, spatial and geometry. I have given moving wall boundary condition from material frame of view. How to view this from fluid reference frame? when I use moving mesh model I could see all these reference frame in action. But my physics could not be solved easily in moving mesh owing to mesh deformation. But I get proper results in stationary frame of reference.
I want to create some animation and view it from the fluid point of view. Is it possible? I have seen this kind of transofmrations in many other cfd software. Is it possible in comsol?

Please some one enlighten me...

with regards
Siva
I could see in the animation setting various frames like: material, mesh, spatial and geometry. I have given moving wall boundary condition from material frame of view. How to view this from fluid reference frame? when I use moving mesh model I could see all these reference frame in action. But my physics could not be solved easily in moving mesh owing to mesh deformation. But I get proper results in stationary frame of reference. I want to create some animation and view it from the fluid point of view. Is it possible? I have seen this kind of transofmrations in many other cfd software. Is it possible in comsol? Please some one enlighten me... with regards Siva
Siva Kumar Manickam
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Posted: 1 decade ago Feb 8, 2012, 8:13 p.m. EST
hello every one,
plz give some input for my problem.
thanks.
hello every one, plz give some input for my problem. thanks.
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 9, 2012, 1:47 a.m. EST
Hi

do not mix up all frames, read carefully the doc and do some simple examples.

CFD fluid motion is not directly related to the mesh motion, the ALE is used only for the fluid structure interactions, when the structure deforms and changes the overall shape of the fluid, then the meshing (mathematical sampling of the space for the CFD calulations) also deforms to follow, but the fluid flows over the mesh

--
Good luck
Ivar
Hi do not mix up all frames, read carefully the doc and do some simple examples. CFD fluid motion is not directly related to the mesh motion, the ALE is used only for the fluid structure interactions, when the structure deforms and changes the overall shape of the fluid, then the meshing (mathematical sampling of the space for the CFD calulations) also deforms to follow, but the fluid flows over the mesh -- Good luck Ivar
Siva Kumar Manickam
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Posted: 1 decade ago Feb 9, 2012, 2:01 a.m. EST
Thanks dr. Ivar.
I am using stationary frame (2d spf) only - from boat. But thought whether we can visualize results/animations as if we are in a fluid? Because I have read somewhere that it is possible to view the results from other frame (for example results of velocity values given to fluid) and one can see moving bodies. Is that possible?

A such example of simulation where solution is obtained in body-fitted frame and visualised in a moving frame is available here: www.math.gatech.edu/~alben/Fig1Movie.mov

with regards,
Siva
Thanks dr. Ivar. I am using stationary frame (2d spf) only - from boat. But thought whether we can visualize results/animations as if we are in a fluid? Because I have read somewhere that it is possible to view the results from other frame (for example results of velocity values given to fluid) and one can see moving bodies. Is that possible? A such example of simulation where solution is obtained in body-fitted frame and visualised in a moving frame is available here: http://www.math.gatech.edu/~alben/Fig1Movie.mov with regards, Siva
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 9, 2012, 3:38 a.m. EST
Hi

but none of the COMSOL frames corresponds to the fluid motion frame (the boat in the stream), you are either on the shore, or on the flexible solid part in the stream, and you can show the "particles moving" but you canot look at he environment from a particle (except if you implement it via equations yourself, always possible)

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Good luck
Ivar
Hi but none of the COMSOL frames corresponds to the fluid motion frame (the boat in the stream), you are either on the shore, or on the flexible solid part in the stream, and you can show the "particles moving" but you canot look at he environment from a particle (except if you implement it via equations yourself, always possible) -- Good luck Ivar
Siva Kumar Manickam
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Posted: 1 decade ago Feb 9, 2012, 4:33 a.m. EST
thank you dr.
yes, actually that is my aim. having solved from boat, is it possoble to visualise from shore? that is we can post process as if solved from shore?
thank you dr. yes, actually that is my aim. having solved from boat, is it possoble to visualise from shore? that is we can post process as if solved from shore?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 9, 2012, 7:59 a.m. EST
Hi

from my understanding you do (with COMSOL) solve from the "shore" with particle tracking giving the closest to "boat" view, or am I wrong ?

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Good luck
Ivar
Hi from my understanding you do (with COMSOL) solve from the "shore" with particle tracking giving the closest to "boat" view, or am I wrong ? -- Good luck Ivar
Siva Kumar Manickam
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Posted: 1 decade ago Feb 11, 2012, 6:27 a.m. EST
Thank you Dr. Ivar.
Is int it otherwise?
For example if I do the simulation with 2d spf of flow past sphere, where the fluid around sphere moves with respect to sphere due to to moving wall BC. Is not it in boat's view?
I actually want to see how sphere will move in fluid due to the velocity induced. This is view from shore, right. Please correct me if I am wrong.
Is this approach of visualisation is possible in Comsol?

With regards
Siva
Thank you Dr. Ivar. Is int it otherwise? For example if I do the simulation with 2d spf of flow past sphere, where the fluid around sphere moves with respect to sphere due to to moving wall BC. Is not it in boat's view? I actually want to see how sphere will move in fluid due to the velocity induced. This is view from shore, right. Please correct me if I am wrong. Is this approach of visualisation is possible in Comsol? With regards Siva
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 11, 2012, 6:36 a.m. EST
Hi
indeed references is always a point of view, the main difference between the moving and the fixed frame is the second derivative item of the frame itself, there are a few interesting books talking about this, among other the one(s) of Axisa, check the FORUM, the references are given a few times, and there are a few older treads on that subject

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Good luck
Ivar
Hi indeed references is always a point of view, the main difference between the moving and the fixed frame is the second derivative item of the frame itself, there are a few interesting books talking about this, among other the one(s) of Axisa, check the FORUM, the references are given a few times, and there are a few older treads on that subject -- Good luck Ivar
Siva Kumar Manickam
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Posted: 1 decade ago Feb 11, 2012, 6:41 a.m. EST
I am sorry Dr. Ivar, I dint get the book names.
would you please tell me which book I can refer to understand this reference frames concepts in CFD?
I am sorry Dr. Ivar, I dint get the book names. would you please tell me which book I can refer to understand this reference frames concepts in CFD?
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 11, 2012, 7:54 a.m. EST
Hi

what about trying a search on the Forum, with the word "Axisa" ;)

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Good luck
Ivar
Hi what about trying a search on the Forum, with the word "Axisa" ;) -- Good luck Ivar
Siva Kumar Manickam
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Posted: 1 decade ago Feb 11, 2012, 9:48 a.m. EST
Oh sorry...
I got that :
Modelling of Mechanical Systems: Fluid-Structure Interaction, F. Axisa ....
Thanks for your feedbacks.
With regards
Siva
Oh sorry... I got that : Modelling of Mechanical Systems: Fluid-Structure Interaction, F. Axisa .... Thanks for your feedbacks. With regards Siva
Siva Kumar Manickam
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Posted: 1 decade ago Feb 26, 2012, 8:57 p.m. EST
Dear Dr. Ivar
Thank you very much. I think now I found answer.
I solve 2D spf in body-fitted frae (boat) and use another ALE mesh give the calculated velocity or displacement to the moving body. It looks 'like' the solution is solved from 'shore'.

Actually upon digging the forum further, I understood that there is spf cum ALE built in but given in twophase flow-moving mesh module, which has built in modules to serve my purpose.

Simulation runs smoothly and I am able to get the results.

Salute you sir,
Siva
Dear Dr. Ivar Thank you very much. I think now I found answer. I solve 2D spf in body-fitted frae (boat) and use another ALE mesh give the calculated velocity or displacement to the moving body. It looks 'like' the solution is solved from 'shore'. Actually upon digging the forum further, I understood that there is spf cum ALE built in but given in twophase flow-moving mesh module, which has built in modules to serve my purpose. Simulation runs smoothly and I am able to get the results. Salute you sir, Siva
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)
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Posted: 1 decade ago Feb 27, 2012, 1:10 a.m. EST
Hello

that is good to hear, COMSOL is a marvellous tool to get to really learn physics, and even if I though I knew Physics, I'm astonished how many times I had misseed essential subtilities ;)

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Good luck
Ivar
Hello that is good to hear, COMSOL is a marvellous tool to get to really learn physics, and even if I though I knew Physics, I'm astonished how many times I had misseed essential subtilities ;) -- Good luck Ivar

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