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doc:user:remeshing:remeshing [2016/06/13 17:29] – [Dynamic balancing] jorisdoc:user:remeshing:remeshing [2018/05/04 15:47] – ↷ Links adapted because of a move operation boman
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 Second, [[doc/user/meshtransfer/datatransferbetweenmeshes|data must be transferred]] from the old to the new mesh. As you very well know, the Gauss points contains information about strains and stresses, and the nodes about displacements, velocities and temperatures. However, just after remeshing, the newly defined nodes and Gauss points do not know anything, since they were just created ! If we do not want to loose what was computed during the previous time integration, then data (stresses, temperatures, velocities...) must be transferred to the new mesh. Second, [[doc/user/meshtransfer/datatransferbetweenmeshes|data must be transferred]] from the old to the new mesh. As you very well know, the Gauss points contains information about strains and stresses, and the nodes about displacements, velocities and temperatures. However, just after remeshing, the newly defined nodes and Gauss points do not know anything, since they were just created ! If we do not want to loose what was computed during the previous time integration, then data (stresses, temperatures, velocities...) must be transferred to the new mesh.
  
-Once this is done (it used to take a bloody hell of a f***ing time, but now the time required is more reasonable, see [[commit:01_19]] for details), we have a good new mesh, containing data from the previous computation. From this, the simulation can be restarted, which means that the time integration is carried out further, until the remeshing criterion is met again and another remeshing operation takes place.+Once this is done (it used to take a bloody hell of a f***ing time, but now the time required is more reasonable, see [[commit:2016:01_19]] for details), we have a good new mesh, containing data from the previous computation. From this, the simulation can be restarted, which means that the time integration is carried out further, until the remeshing criterion is met again and another remeshing operation takes place.
  
 And that's it for the basics ! But as they say, a picture is worth a thousand words, and I guess that a video is worth a thousand pictures, so just enjoy the following video, about the modelling of forging, to see how it works : And that's it for the basics ! But as they say, a picture is worth a thousand words, and I guess that a video is worth a thousand pictures, so just enjoy the following video, about the modelling of forging, to see how it works :
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 For the advanced user, a few options can be played with by changing the three of arguments.  For the advanced user, a few options can be played with by changing the three of arguments. 
  
-First of all, it is possible to deactivate the ''stepPredictor()''. If you do not know what it is, do not touch it. If you do, well sometimes, when transfer errors are significant, the balancing can go better if executed without this predictor, so without extrapolating the next step based on velocities and accelerations. This is fine only in quasi-static, because in dynamic computations velocities and accelerations also intervene in the computation of forces. To do so, simply set the second argument to ''False''+First of all, it is possible to deactivate the ''stepPredictor()''. If you do not know what it is, do not touch it. If you do, well sometimes, when transfer errors are significant, the balancing can go better if executed without this predictor, so without extrapolating the next step based on velocities and accelerations. This is fine only in quasi-static, because in dynamic computations velocities and accelerations also intervene in the computation of forces. To do so, simply set the second argument to ''False''. If have not investigated this greatly, but I believe that this could be a sign that the mesh of the computation was not fine enough, so activating this option could hide the real problem. I believe it should be reserved for battery tests, because we want to have tests with rather coarse meshes there
  
 Second, the number of iterations for each step of the balancing can be changed. By default, seven iterations are tried before increasing the fraction of the unbalanced forces and starting again. Second, the number of iterations for each step of the balancing can be changed. By default, seven iterations are tried before increasing the fraction of the unbalanced forces and starting again.
  
-Finally, the tolerance can also be changed. The parameter $\alpha$, used to ponder the unbalanced forces, starts at 1 and is progressively divided by 2 when a step fails. Once $\alpha$ becomes smaller than the tolerance, the algo stops itself, returns an error, and the temporal interation does not restart. The default value of 0.001 can be changed if needed. +Finally, the tolerance can also be changed. The parameter $\alpha$, used to ponder the unbalanced forces, starts at 1 and is progressively divided by 2 when a step fails. Once $\alpha$ becomes smaller than the tolerance, the algo stops itself, returns an error, and the temporal integrationdoes not restart. The default value of 0.001 can be changed if needed.  
 + 
 + --- //[[pjoris@ulg.ac.be|Pierre Joris]] 2016/06/13 //
doc/user/remeshing/remeshing.txt · Last modified: 2024/03/01 16:17 by boman

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