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[Jan Stránský <honzik.stransky@xxxxxxxxx>]

>
> thank you very much! So i will try it first with the PWaveTimeStep and
> add PWaveTimeStep later to compare the results.
>
> But now i'm interested in the option to set dt manually, where can i
> find some advices to do it in this way? Because i didn't find so many
> formulas for FrictMat_FrictPhys in the documentation to calculate
> different things for it!
>

For the case of FrictMat_FrictPhys it is mentioned in [1]. The critical
time step for discrete systems (mass spring systems), which Yade actually
simulate, is given by

dT = sqrt( M / k_N )
where  M=density*4/3.*pi*r*r*r  is mass of the particle and k_N [N/m]
normal stiffness of contacts / interactions / bonds. Specifically for
Frict_phys it is (according to [1] )
k_N = 2*young*r

good luck and if you have more questions, just ask :-)

Jan

[1]
https://yade-dem.org/doc/formulation.html#estimation-of-by-wave-propagation-speed