Grain-grain and grain-wall friction

Submitted by hkustdebris on Tue, 04/26/2016 - 09:50

I want to specify two friction angles for a simulation - one for between pairs of grains, and a lower one between grains and walls. For preliminary simulations, I have been using the following to define friction:

fix m4 all property/global coefficientFriction peratomtypepair 1 ${intfriction}

I note from the documentation that I can specify more than one 'peratomtypepair', specifying the friction angle between different grain types. Can I also specify a wall type here, since walls appear to infinitely large spheres? Also, is enabling 'tangential damping' for fix wall/gran a necessity?

fix wallprop all wall/gran model hooke tangential history mesh n_meshes 2 meshes mesh-1 mesh-2 tangential_damping on

(My understanding is that the ultimate required effect is to somehow reduce the damping terms for the Hertz model interaction between grain and wall. I am sorry if the answer is in the documentation somewhere, but I have thus far struggled to find it.)

Many thanks!
Georg

Forums:

aaigner's picture

aaigner | Mon, 05/02/2016 - 16:25

Hi Georg,

yes you can define multiple material types (see create_box) Then you can give your particles one type and the wall another one.

Bests
Andreas

hkustdebris | Tue, 05/03/2016 - 09:13

Hi Andres,

Thanks very much for the hints! I didn't think to check 'create_box'. I now have two friction angles defined.

Best regards,
Georg