Question related to particles insertion

Submitted by gibel on Mon, 05/09/2022 - 08:12

I need to make one thing clear about particle insertion in rotating drum.

I have two different simulations with mixed particles.

Simulation one: particles radius 0.04 and radius 0.035

Simulation two : particles radius 0.04 and radius 0.025

I am inserting particles volume wise like 20 % 0.04 and 80 % another one in both simulations.

I realized that number of inserted particles with 0.04 in simulation one is more than number of inserted particles with 0.04 in simulation two (huge difference).

Is it normal?
Is it because of radius 0.035 and 0.025 ?

I was expecting almost equal number.
Is it possible to get almost equal number of 0.04 size from both simulation?
Note: I don't want to insert number wise. I checked that number wise gives me almost equal number. But I have to do it volume wise.

Thank you

mschramm | Mon, 05/09/2022 - 19:11

Hello,
After the insertion, is LIGGGHTS giving a warning that "not all particles were able to be inserted"?

LIGGGHTS will insert the largest particle first and then insert the smaller one. They do this to maximize packing.

Have you seen similar results when inserting both particles into a large area?

gibel | Tue, 05/10/2022 - 02:42

Hello mschramm

Thank you for your reply.
There is no warning in simulation.

```
This is my log file:

run ${fillsteps}
run 20000
Setting up run at Tue May 3 14:28:37 2022

INFO: Particle insertion ins: 68.360585 particles every 1333 steps - particle rate 512.832594, (mass rate 5.000000e+01)
1025 particles (mass 9.993515e+01) within 18662 steps
Memory usage per processor = 11.85 Mbytes
Step Atoms KinEng CPU
0 0 0 0
INFO: Particle insertion ins: inserted 68 particle templates (mass 6.492625e+00) at step 1
- a total of 68 particle templates (mass 6.492625e+00) inserted so far.
INFO: Particle insertion ins: inserted 69 particle templates (mass 6.775368e+00) at step 1334
- a total of 137 particle templates (mass 1.326799e+01) inserted so far.
INFO: Particle insertion ins: inserted 68 particle templates (mass 6.691592e+00) at step 2667
- a total of 205 particle templates (mass 1.995959e+01) inserted so far.
INFO: Particle insertion ins: inserted 68 particle templates (mass 6.492625e+00) at step 4000
- a total of 273 particle templates (mass 2.645221e+01) inserted so far.
INFO: Particle insertion ins: inserted 69 particle templates (mass 6.775368e+00) at step 5333
- a total of 342 particle templates (mass 3.322758e+01) inserted so far.
INFO: Particle insertion ins: inserted 69 particle templates (mass 6.775368e+00) at step 6666
- a total of 411 particle templates (mass 4.000295e+01) inserted so far.
INFO: Particle insertion ins: inserted 68 particle templates (mass 6.691592e+00) at step 7999
- a total of 479 particle templates (mass 4.669454e+01) inserted so far.
INFO: Particle insertion ins: inserted 69 particle templates (mass 6.775368e+00) at step 9332
- a total of 548 particle templates (mass 5.346991e+01) inserted so far.
INFO: Particle insertion ins: inserted 68 particle templates (mass 6.492625e+00) at step 10665
- a total of 616 particle templates (mass 5.996253e+01) inserted so far.
INFO: Particle insertion ins: inserted 69 particle templates (mass 6.775368e+00) at step 11998
- a total of 685 particle templates (mass 6.673790e+01) inserted so far.
INFO: Particle insertion ins: inserted 69 particle templates (mass 6.576401e+00) at step 13331
- a total of 754 particle templates (mass 7.331430e+01) inserted so far.
INFO: Particle insertion ins: inserted 69 particle templates (mass 6.775368e+00) at step 14664
- a total of 823 particle templates (mass 8.008967e+01) inserted so far.
INFO: Particle insertion ins: inserted 68 particle templates (mass 6.492625e+00) at step 15997
- a total of 891 particle templates (mass 8.658229e+01) inserted so far.
INFO: Particle insertion ins: inserted 68 particle templates (mass 6.691592e+00) at step 17330
- a total of 959 particle templates (mass 9.327389e+01) inserted so far.
INFO: Particle insertion ins: inserted 66 particle templates (mass 6.524041e+00) at step 18663
- a total of 1025 particle templates (mass 9.979793e+01) inserted so far.
20000 1025 2.5853549 4.8901582
Loop time of 4.89017 on 1 procs for 20000 steps with 1025 atoms, finish time Tue May 3 14:28:42 2022

Pair time (%) = 1.69336 (34.6278)
Neigh time (%) = 0.749503 (15.3267)
Comm time (%) = 0.0137772 (0.281732)
Outpt time (%) = 0.175141 (3.58148)
Other time (%) = 2.25839 (46.1823)

Nlocal: 1025 ave 1025 max 1025 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Nghost: 0 ave 0 max 0 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Neighs: 3301 ave 3301 max 3301 min
Histogram: 1 0 0 0 0 0 0 0 0 0

Total # of neighbors = 3301
Ave neighs/atom = 3.22049
Neighbor list builds = 2021
Dangerous builds = 0
#run 1000000 upto

unfix ins

run ${fillsteps}
run 20000
Setting up run at Tue May 3 14:28:42 2022

Memory usage per processor = 18.4443 Mbytes
Step Atoms KinEng CPU
20000 1025 2.5853549 0
40000 1025 4.041498e-09 8.2804162
Loop time of 8.28043 on 1 procs for 20000 steps with 1025 atoms, finish time Tue May 3 14:28:50 2022

Pair time (%) = 4.64065 (56.0436)
Neigh time (%) = 0.148436 (1.79261)
Comm time (%) = 0.00528701 (0.0638495)
Outpt time (%) = 0.306052 (3.69609)
Other time (%) = 3.18001 (38.4039)

Nlocal: 1025 ave 1025 max 1025 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Nghost: 0 ave 0 max 0 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Neighs: 3515 ave 3515 max 3515 min
Histogram: 1 0 0 0 0 0 0 0 0 0

Total # of neighbors = 3515
Ave neighs/atom = 3.42927
Neighbor list builds = 163
Dangerous builds = 0

#run 7000000 upto

fix MoveDrum all move/mesh mesh Drum rotate origin 0 0 0 axis 1. 0. 0. period ${drumPeriod} #Rotation of drum
fix MoveDrum all move/mesh mesh Drum rotate origin 0 0 0 axis 1. 0. 0. period 4
fix MoveFront all move/mesh mesh Front rotate origin 0 0 0 axis 1. 0. 0. period ${drumPeriod} #Rotation of front face
fix MoveFront all move/mesh mesh Front rotate origin 0 0 0 axis 1. 0. 0. period 4
fix MoveBack all move/mesh mesh Back rotate origin 0 0 0 axis 1. 0. 0. period ${drumPeriod} #Rotation of back face
fix MoveBack all move/mesh mesh Back rotate origin 0 0 0 axis 1. 0. 0. period 4

run ${rotasteps}
run 600000
Setting up run at Tue May 3 14:28:50 2022

Memory usage per processor = 18.4443 Mbytes
Step Atoms KinEng CPU
40000 1025 4.041498e-09 0
640000 1025 33.979559 402.46906
Loop time of 402.469 on 1 procs for 600000 steps with 1025 atoms, finish time Tue May 3 14:35:32 2022

Pair time (%) = 112.304 (27.9037)
Neigh time (%) = 67.2125 (16.7)
Comm time (%) = 0.831966 (0.206715)
Outpt time (%) = 9.13403 (2.2695)
Other time (%) = 212.987 (52.92)

Nlocal: 1025 ave 1025 max 1025 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Nghost: 0 ave 0 max 0 min
Histogram: 1 0 0 0 0 0 0 0 0 0
Neighs: 2727 ave 2727 max 2727 min
Histogram: 1 0 0 0 0 0 0 0 0 0

Total # of neighbors = 2727
Ave neighs/atom = 2.66049
Neighbor list builds = 74717
Dangerous builds = 0

Is there any issue with particles insertion?
Thank you

Daniel Queteschiner | Mon, 05/16/2022 - 14:34

What's the exact fix command (and options) you're using for insertion?