region box is extended when particle hit a wall.

Submitted by weiyi on Wed, 10/23/2013 - 07:07

I called command insert/pack to insert particles with a constant horizontal velocity(Vx). when particles hit a wall,　the wall started to move and region created by create_box become larger and larger. particles moved out of original region area. I could not understand why reason it cause region box became larger and larger.
Does it means that results of calculation is wrong and some parameters like horizontal velocity, radius of particle etc. should be changed.

Thanks in advance.

Simon

Forums:

cstoltz | Wed, 10/23/2013 - 12:50

Sorry, don't quite understand your question. How have you specified the wall motion? What boundaries did you specify?

Can you post the input deck?

Regards,
Chris

weiyi | Thu, 10/24/2013 - 09:03

Hi Chris

Thanks for your prompt reply.

I modified sample codes cohesion and let particles hit xplane wall with a horizontal velocity. I wants to investigate cohesion functionality to see if particles can be stuck to the wall or not. When cohesionEnergyDensity=300000, particles can
not be stuck. At cohesionEnergyDensity=1200000. when particles hit the xplane wall, the particles moved with xplane wall. I didn't know why? I think my xplane wall is fixed. it can not be moved. I pasted my codes and you can try it. Are there some wrong in my codes.

=======================================================

#Contact model example

atom_style granular
atom_modify map array
boundary m m m
newton off

communicate single vel yes

units si

region reg block -0.05 0.05 -0.05 0.05 0. 0.15 units box
create_box 1 reg

neighbor 0.002 bin
neigh_modify delay 0

#Material properties required for new pair styles

fix m1 all property/global youngsModulus peratomtype 5.e6
fix m2 all property/global poissonsRatio peratomtype 0.45
fix m3 all property/global coefficientRestitution peratomtypepair 1 0.9
fix m4 all property/global coefficientFriction peratomtypepair 1 0.05
fix m5 all property/global characteristicVelocity scalar 2.
fix m6 all property/global cohesionEnergyDensity peratomtypepair 1 1200000
#fix m7 all property/global coefficientRollingFriction peratomtypepair 1 0.1

#New pair style
pair_style gran/hertz/history cohesion sjkr #Hertzian with cohesion cohesion sjkr
pair_coeff * *

#timestep 0.00001
timestep 1e-10
fix gravi all gravity 9.81 vector 0.0 0.0 -1.0
fix zwalls1 all wall/gran/hertz/history primitive type 1 zplane 0.0
fix zwalls2 all wall/gran/hertz/history primitive type 1 zplane 0.15
fix xwalls3 all wall/gran/hertz/history primitive type 1 xplane 0.05 cohesion sjkr
fix xwalls4 all wall/gran/hertz/history primitive type 1 xplane -0.05
fix ywalls5 all wall/gran/hertz/history primitive type 1 yplane 0.05
fix ywalls6 all wall/gran/hertz/history primitive type 1 yplane -0.05
#fix cylwalls all wall/gran/hertz/history primitive type 1 zcylinder 0.05 0.0 0.0 cohesion sjkr

#region for insertion
#region bc cylinder z 0.01 0.01 0.025 0.05 0.0603 units box
region bc cylinder x 0.0 0.08 0.002 0.045 0.0451 units box
#region bc sphere 0.02 0.0 0.1 0.005 side in
# region bc cylinder x 0.0 0.08 0.0025 0.045 0.0451 units box #ok 20
# region bc cylinder x 0.0 0.08 0.006 0.045 0.0451 units box # ok 100 3000000
group nve_group region reg

#distributions for insertion
fix pts1 all particletemplate/sphere 5330 atom_type 1 density constant 1500 radius constant 0.0000005 volume_limit 1e-20
fix pdd1 all particledistribution/discrete 5331 1 pts1 1.0

#particle insertion
fix ins nve_group insert/pack seed 5332 distributiontemplate pdd1 &
maxattempt 100 insert_every 9900000 overlapcheck yes all_in yes vel constant 15.0 0.0 0.0 &
region bc particles_in_region 20 ntry_mc 10000

#apply nve integration to all particles that are inserted as single particles
fix integr nve_group nve/sphere

#output settings, include total thermal energy
compute rke all erotate/sphere
thermo_style custom step atoms ke c_rke vol
thermo 1000
thermo_modify lost ignore norm no
compute_modify thermo_temp dynamic yes

#insert the first particles so that dump is not empty
run 1
dump dmp all custom 800000 post/dump*.cohesion id type type x y z ix iy iz vx vy vz fx fy fz omegax omegay omegaz radius

#insert particles --49000000 --800000 --100000
run 100000
unfix ins

#run
run 9000000 upto

=========================================

Best regards

Simon

ckloss's picture

ckloss | Thu, 10/31/2013 - 12:20

Hi Simon,

if I understand you correctly, you want your box not to change? Have a look at the boundary command in this case

Cheers
Christoph