insert/rate/region fix warning

Hi!

I have recently switched to LIGGGHTS 2 and having some issues while running the insert/rate/region fix.

fix ins1 nve_group insert/rate/region seed 10001 distributiontemplate pdd2 mass 3.888 massrate 3.888 insert_every 1 region bc

But it give sthe following warnings, could anybody explain the reason. I am also attaching the input script.

WARNING: Particle insertion : Inserting no particle - check particle insertion settings (fix_insert.cpp:469)

Thanks,
TM

Attachment	Size
in.experiment_05_03_2012_layer1.liggghts.txt	3.93 KB

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LIGGGHTS® - User Forum

ckloss | Mon, 10/01/2012 - 16:45

To me it seems that because

To me it seems that because you are inserting too often, the number of particles to insert each step would be 0. Typically, you don't insert every step (this is very inefficient)

Cheers, Christoph

Tamoghna | Mon, 10/01/2012 - 17:00

Hi Christoph! Thanks a lot..

Hi Christoph!

Thanks a lot.. I just figured it out, actually the mass rate was so less that only 452 particles were to be charged in 10⁶ steps.... So, I increased the massrate.

Is there a way to stop the warnings to display!!!

Thanks,
TM

rahulsoni | Thu, 02/27/2014 - 15:16

Massrate

I am running a simulation with fix insert/stream command. Following is the command in script.

fix insertion particles insert/stream seed 5330 distributiontemplate pdd1
& verbose yes maxattempt 100 mass INF massrate 1.0 start 1000 overlapcheck yes vel constant 0. 0. -1.0 & insertion_face inface extrude_length 0.4

I have assigned massrate = 1.0 but I really don't know how much actually it is. Simulation script is in SI units but from results I do not get mass insetion any way near to 1.0 kg/second or something like that. Please tell me how much actually it is.....

nasato | Thu, 02/27/2014 - 17:02

Hi Rahul,

It should be 1 Kg/s if you are using SI units. What may cause this problem is if you have an insertion region too small compared to your mass rate, so it won't be possible to generate the desired mass rate.
Check if you are getting warnings "Less particles inserted than requested" during run time. This indicates problem. If this happens, try either increase the extrude_length size or increase the area of the region you are inserting your particles. You may also try to increase the initial velocities that particles are created.
Cheers,
nasato

rahulsoni | Fri, 02/28/2014 - 06:08

Hi Nasato

Thanks for the info but I have something peculiar. Actually, mine is the break particle simulation. When a particle breaks it gets replaced new size distribution elsewhere. Each time computer calculates the mass distribution and prints in a separate file. In this way, the mass I am getting after around 25,00,000 steps is 1.5 around. Time step size is in the order of 5e-08.

I have recalculated things and as suggessted I found that there is huge mass loss due to either high rate of insertion or smaller insertion volume.

Thanks Nasato for the info...