Hello Team, I want to specify frictionless primitive wall. I'm having a triclinic box, with particles and primitive walls defined as type 1 and 2, respectively, and important lines in input script are as follows.
boundary p f p
fix m3 all property/global coefficientRestitution peratomtypepair 2 ${EC} 1.0 1.0 1.0
fix m4 all property/global coefficientFriction peratomtypepair 2 ${MU} 0.0 0.0 0.0
pair_style gran model hooke tangential history
fix yMaxWall all wall/gran model hooke tangential history allow_special_domain_periodic yes primitive type 2 yplane ${yMax}
fix yMinWall all wall/gran model hooke tangential history allow_special_domain_periodic yes primitive type 2 yplane ${yMin}
fix fixMomentum all momentum 1 linear 1 1 1 ##
fix boxDeform all deform 1 xy erate ${dimShearRate} remap v
As you can see,
--> I'm putting primitive walls in y-direction.
--> When primitive walls are defined for triclinic box, LIGGGHTS suggests using "allow_special_domain_periodic yes"
--> I've set particle-wall interaction friction coefficient to 0.0 and restitution coefficient to 1.0
But I still see the effect of wall (that is, particles are retarded drastically, close to the stationary wall here).
What else is needed to bring down wall's effect?
mschramm | Thu, 07/08/2021 - 16:33
turn off tangential
Hello,
Have you tried turning off the tangential portion on the wall?
Simply use the pair model model hooke tangential noHistory (or something similar...).
jagan1mohan | Fri, 07/09/2021 - 07:22
no_history....
Hello Matthew, I've tried "tangential no_history" for primitive walls as shown below, but it did not work.
fix yMaxWall all wall/gran model hooke tangential no_history allow_special_domain_periodic yes primitive type 2 yplane ${yMax} shear x ${plateVelocity}
fix yMinWall all wall/gran model hooke tangential no_history allow_special_domain_periodic yes primitive type 2 yplane ${yMin} shear x -${plateVelocity}
I think the primitive wall is at rest, by default. I've also tried applying a shear velocity to primitive wall equivalent to that produced by fix deform but it did not work as well.
What else is needed to bring down wall's effect?