Yade

Density Scaling

Asked by Sina Jafari

Hello everyone,

I'm using density scaling in a quasi-static simulation to speed up but I've got some problems:
1. I changed densityScaling to True in newton engine and also changed densityScaling to True in timestepper engine and specified a targetDt in timestepper but the problem is that I don't know what happens in the simulation now?! I mean I don't know the applied scaling factor is constant or changing during the simulation? and how large it is?
2. What happens when I turn densityScaling to True in timestepper?
3. How does density scaling affect contact forces?
Thank you very much for your kind considerations.

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Bruno Chareyre
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Bruno Chareyre (bruno-chareyre) said : 		#1

0. Sorry but... did you read the parameter's documentation??
1. Changing all the time
2. long storry, there is a bibliographic reference in the documentation
3. it should not as long as your are nearly quasistatic

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Sina Jafari (sinajafari88) said : 		#2

Thanks Bruno that helped a lot... How can I determine the suitable value for targetDt? Is there a limit or something? and generally does density scaling affect fabric evolution in a quasi-static simulation? any references or papers?

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Best Bruno Chareyre (bruno-chareyre) said : 		#3

targetDt can be anything, it doesn't matter. You need to think in a "per
iteration" way for e.g. strain rate, and then it doesn't matter what dt is.
Quasi-static means independent of inertial effects, thus independent of
what you do with density (be it for fabric or other things).
I don't know any publication about this other than PFC manual.

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Sina Jafari (sinajafari88) said : 		#4

Thanks Bruno Chareyre, that solved my question.