reason for uncongergable simulations

Hi Christoph, Hi LIGGGGHTSers,
Rencently, i am working on simulations of stirring a peller (steel) in a vassel with particles (radii =1 mm, glass beans ). The simulation behave strangely, withparticles flowing everywhere out of control (cf. attached figure: bad_normal_e). The properties are given at the bottom.

I ve checked choice of timestep (considering the moving mesh, timestep sometimes should be much smaller than the critical time step )
crtical timestep given by Rayleigh eqation is 10^-6 for the given parameter. I haved used 1.e-6 s , 1e-7s , 1e-8s . its not converged in any case. very time comsumining, not tried even smaller timestep.

I used smaller Young's mudulus (E in the range of 5e6-2e8). it works fine (cf. figure: good_lower_e). But it is not a final solution!!!!

What reason do you think it could be:
mesh size?
time step too large?
or other reason?

Thank you in avdvance for your expertise!

Cheers,

ZYan

fix m1 all property/global youngsModulus peratomtype 50.e9 180.e9 # mater 1 for particle, material 2 for peller
fix m2 all property/global poissonsRatio peratomtype 0.25 0.3
fix m3 all property/global coefficientRestitution peratomtypepair 2 0.6 0.7 0.7 0.7
fix m4 all property/global coefficientFriction peratomtypepair 2 0.1 0.3 0.3 0.3
fix m5 all property/global coefficientRollingFriction peratomtypepair 2 0.005 0.005 0.005 0.005

pair_style gran/hertz/history
pair_coeff * *
timestep 0.00000001
.
.

# mesh movement
fix bladedown all move/mesh mesh blade linear 0.0 -0.0017364817 0.0
fix rotation all move/mesh mesh blade rotate origin 0.0 0.0 0.0 axis 0 -1.0 0 period 15.3