Pour command

Submitted by cstoltz on Tue, 06/01/2010 - 19:20

Hi Christoph,

I was looking at the pour command and had two questions:

1) Is it possible to specify a rate of particle generation? i.e. say I want to create N particles/second. Other than trying to size my region where the particles are to be created to fit this rate, how could I go about this?

2) Is the generation rate based solely on the time it takes particles to clear the region due to gravity, or does it also factor in any initial velocity assigned to the plate. I would like to create a very thin generation region and assign an initial velocity to the particles to help them clear the region quickly.

Thanks,
Chris

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ckloss's picture

ckloss | Tue, 06/01/2010 - 19:57

Hi Chris,

good questions!

Question 1 will be answered in the release rate of version 1.0.3, to be (hopefully) released on Thursday.
1.0.3 will contain a new pour command that allows discrete particle distributions, restart capability, definition of total insertion mass and mass-flow rate BCs (e.g. kg/s)

Regarding question 2:
>> Is the generation rate based solely on the time it takes particles to clear the region due to gravity, or does it also factor in any initial velocity assigned to the plate
Gravity + initial particle velocity+ region movement in z-direction

The new pour command will also have a re-worked insertion height probability distribution that is in accordance with the velocity distribution over height as the current implementation in LAMMPS/LIGGGHTS is not correct.

>> I would like to create a very thin generation region and assign an initial velocity to the particles to help them clear the region quickly.
Depends on if your particle insertion belongs to a physical process, or if it is just used to generate some packing.
In case I, the initial velocity is given by the process and should not be changed. In case II, you are right but I would be careful not to insert particles too often as it triggers neigh list rebuild. Moreover, in parallel, one should tend to have as few insertion steps as possible (e.g. by extending the insertion volume).

best,
Christoph