Mass rate adjustment with Insert/stream - Less particle insertion

Submitted by nicolas.aalderete on Tue, 08/09/2016 - 15:55

Hi,

I have been dealing with a problem for several days now and I can't seem to be able to fix it.

I need to feed a transfer chute with 278 kg/s. I wrote fix insert/stream 278kg 278kg/s (mass mass rate) and simulate for 1 second. I was expecting to see 278 kg inserted throught my simulation but instead I only got 160 kgs approximately. No matter which values I used I kept getting the same result (WARNING LESS PARTICLES INSERTION THAN EXPECTED). I wanted to know if there is a reason why the sistem only seems to be able to feed a maximum number of particles.

I later tried the fix insert/stream with nparticles particles rate and I got a better result achieving a mass rate of 220 kg/s but still not close to the 278 kg/s. Can anyone explain how the fix insert/stream works and how I can solve my problem?

Another doubt is why do I need to specify mass when I input a mass rate and a total simulation time (shouldn't the mass be equal to mass rate times the duration of the insertion?).

Thanks in advance,

Nicolas

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Daniel Queteschiner | Wed, 08/10/2016 - 13:39

As soon as you get this warning you will get neither your desired mass insertion rate nor the specified particle size distribution (in case your particles are not monodisperse). The reason is that there is not enough space to insert all required particles. When LIGGGHTS can not insert any more particles due to not finding any empty position it will just abort insertion for that insertion step. (LIGGGHTS uses a simple sequential inhibition algorithm for insertion.) Adjust insert_every or extrude_length.

The reason for specifying mass and mass rate is that insertion can start and end at any point of the simulation.