How to output solid flux

Submitted by ngcw1986 on Sun, 04/14/2013 - 17:21

Dear Forumers,
I am using Liggghts2.3.2 with its function to calculate solid flux using command "fix massflow/mesh". However, I could not dump/output the flux. I try to wirte its four components using "variables" along with "fix print" command but failed. May be I am not familiar with the function of writing out data of Liggghts. Could any one give me some suggestions? Thanks in advance.

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ckloss's picture

ckloss | Fri, 04/19/2013 - 15:52

Hi ngcw1986,

if you post the error messages others may be able to help you

Cheers
Christoph

ngcw1986 | Fri, 04/26/2013 - 15:45

Hi ckloss,
I read the doc file and try to setup the case: 1. use "fix mesh/surface" together with "fix meshflow/mesh" to inport a sampling surface for mass flow calculating. 2. use variables to extract different components of the "fix meshflow/mesh". 3. use "fix print" to output these variables

the related commands are as follows:
fix face1 all mesh/surface file ../DEM/face1.stl type 1
fix mf all massflow/mesh mesh face1 vec_side 0. 0. -1.0
variable mf1 equal f_mf[1]
variable mf2 equal f_mf[2]
variable mf3 equal f_mf[3]
variable mf4 equal f_mf[4]
variable time equal (step-200000)*dt
fix extra all print 100 "${time} ${mf1} ${mf2} ${mf3} ${mf4}" file ../DEM/massflow.txt title "%" screen no

The calculation is OK, but the output txt file is strange. The time is right but other four variable is always zero. It should has a value large than zero as I do spot solid passing through the surface.
I am sure that the surface is right in the place it should be located and the vec_side is right. But the surface is a stl file of a disc. Does it matter? or am I use a wrong date output method? please shed some light on this to me.
Thanks in advance.

ckloss's picture

ckloss | Thu, 05/02/2013 - 13:28

Hi ngcw1986,

looks like you're using the functionality correctly in the input script. Note that "vec_side" must point to the outside of the mesh, and only particles flowing from "inside" to "outside" are counted

If the problem persists, you could post a simple case to reproduce the issue

Cheers
Christoph

ngcw1986 | Fri, 05/03/2013 - 03:59

Hi ckloss,
I monitor the output file and find it dumped no-zero data when the simulation processed a lot of time. No matter whether the data is reasonable or not, it seems that the function is Ok now. Thanks for your help!

rahulsoni | Thu, 06/27/2019 - 13:52

I struggled a lot with a similar problem. Then the solution was to keep vec_side position sufficiently away from the mass flow mesh.

--
Regards

Rahul Kumar Soni
Scientist, CSIR - IMMT, India