Yade

Cundall Strack Vs Mindlin law

Asked by Sina Jafari

Hi all,
I've read almost every post on contact laws but still I have some questions!

1. I'm trying to model a packing of spheres using mindlin law. My simulation tends to be quasi-static keeping UFI value as low as 0.01 during the simulation. the problem is that I don't know which kind of damping suits my case! Actually by reading previous posts I figured out that cundall's non-viscous damping is meant to be used in quasi-static simulations due to its nature of being applied globally?!

2. Can I use non-viscous damping with mindlin contact law for quasi-static simulations? what if I use viscous damping? Any sources to study the effect of damping (both viscous and non-viscous) on behaviour of the model?

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Václav Šmilauer
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Best Václav Šmilauer (eudoxos) said : 		#1

Hi Sina, if you need to study dynamic behavior, do not EVER use the non-viscous (a.k.a. Cundall numerical) damping - it is nonphysical (not even invariant to coordinate rotation) and a purely numerical tool to reach quasi-static equilibrium without really caring how you get there. That said, it is quite possible that contact damping will do the same job for you, if you need quasi-static; the area seems to be quite murky, so you might need to try both and compare the results - they might end up being very similar. Cheers, v.

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Sina Jafari (sinajafari88) said : 		#2

Thanks Václav Šmilauer, that solved my question.