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any detail information about deformation gradient in fsiFOAM 

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August 6, 2019, 23:14 
any detail information about deformation gradient in fsiFOAM

#1 
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Hojatollah Gholami
Join Date: Jan 2019
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Dear Foamer
I studied article "OpenFOAM FINITE VOLUME SOLVER FOR FLUIDSOLID INTERACTION" that describe fsiFoam solver and also see code of solid solver. it mentioned the deformation gradient as "F=I+trasnpose(DU)", but I saw in the others solid studies as "F=I+DU" for example"https://www.continuummechanics.org/deformationgradient.html". My problem is why it changed? Thanks 

August 8, 2019, 09:14 

#2  
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Hojatollah Gholami
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In Article "A Lagrangian CellCentred Finite Volume Method for Metal Forming Simulation", Page (5), it mentioned "The relative deformation gradient is given in terms of the displacement increment as f = I + ∇(u)T". But I saw in solid mechanics book that the deformation gradient is f =I+∇(u), without transpose.
In OpenFOAM the code of deformation gradient was Quote:
Quote:
because for grad different in OpenFOAM, I found this is it OK? 

August 8, 2019, 11:18 

#3 
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Philip Cardiff
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Location: Dublin, Ireland
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Hi Hojatollah,
Yes your OpenFOAM definition of fvc::grad(U)().T() is correct, and you are correct that it is the same as \frac{\partial U}{\partial X} from your solid mechanics reference. The OpenFOAM definition comes from the outer product of nabla (a vector) and U (a vector), where nabla = (\frac{\partial}{\partial x} \frac{\partial}{\partial y} \frac{\partial}{\partial z}). Hopefully, this makes sense. You can always doublecheck the components to be sure. Philip 

August 8, 2019, 15:40 

#4  
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Hojatollah Gholami
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Quote:


April 6, 2020, 19:48 
No solid deformation by fsiFoam

#5 
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Hi community,
foamextended 4.0, fsiFoam, 2D I have a solidfluid system that I'd like to model. It is a thin horizontal plate (red in the attached figure) fixed at its two end vertical edges. The plate is on top of a flow with an inlet horizontal flow speed. In the middle of the flow, there is a rigid box diverting the flow. I expect this flow diversion to deflect the plate. fsiFoam, however, doesn't capture any solid deformation. My problem is not its visualization in paraview. I have changed the inlet flow speed, elastic modulus and thickness of the plate and the plate just doesn't move. I have built my model following the 3dTube and HronTurelFsi3 tutorials of the fe40/fsiFoam. My case files are attached. Note that I copy and paste the following in my command line to run my case: sed i s/tcsh/sh/g *Links ./removeSerialLinks fluid solid ./makeSerialLinks fluid solid cd fluid ./Allclean ./Allrun I would be thankful if you could help me figure out what the issue is. Hossein 

April 7, 2020, 01:03 

#6 
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Hojatollah Gholami
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Hi,
First in attached files. the coupled in fsiProperties is no, do you sure you change it to yes. 

April 7, 2020, 14:29 

#7  
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Quote:
Thanks Hojatollah and Philip, I set the "coupled" to "yes" and it is working now (wondering why in the 3DTube example with "coupled" set to "off", it was still working!) Another question: How can I add gravity forces to both solid and fluid? Thanks a lot, Hossein 

April 8, 2020, 00:29 

#8  
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Hojatollah Gholami
Join Date: Jan 2019
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Hi
first in 3DTube example, the coupled is yes. May you see HronTurek example that have coupled off and it turn on after 2s by HronTurekReport's object Quote:
In solid region we have bodyForce that read from solidProperties file (g) Quote:
Quote:
First define bodyForce (declare), then read bodyForce (fluidProperties.lookup) and finally add it to momentum equation (UEqn) Don't forget to add similar variable to .H file 

April 10, 2020, 12:31 

#9  
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Quote:
Thanks for your reply. My eventual goals is to simulate a case where the gravity and buoyancy (fluid pushing the plate up when the plate deflects into the fluid) are both taken into account. I am aware that interFoam (VoF twophase flow solver of openFoam) includes the gravity, but not the buoyancy. My simulation isn't a twophase flow case since I only have the fluid and the plate. Is fsiFoam suitable for this simulation? Cheers, Hossein 

August 14, 2020, 07:40 

#10  
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wanghongjie
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