heat transfer between particle and wall

I've tried searching the forums and looking that the tutorial cases, and I can't seem to figure out what I'm doing wrong. I'm trying to simulate a very simple case of particles flowing over a heated cylinder (LIGGGHTS 3.1.0). However, it seems that no matter what order I put the fix commands it, I can't actually get the particles to heat up. Can someone look at my code and see if there's something wrong?

Also, is there a way to get walls to have a heat flux boundary, rather than a specified temperature boundary? I tried using a set command but always got an error saying that there were no particles in the group I was using for the (primitive) wall.

Thanks.

Attachment	Size
test_heat.txt	2.42 KB

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LIGGGHTS® - User Forum

Riccardo Maione | Thu, 09/17/2015 - 09:49

Hello msandli

I think the problem you use two different heat/gran/conduction to include two groups. you can try to eliminate the two lines

fix hg 1 heat/gran/conduction initial_temperature 300 fix hg 2 heat/gran/conduction initial_temperature 1000

with
fix hg all heat/gran/conduction initial_temperature 300

hope it helps
Riccardo

msandli | Thu, 09/17/2015 - 18:00

That, along with changing my

That, along with changing my material properties, fixed it. I was getting a lot of particles with a temperature of '-NaN' before. Thanks a bunch!

How about the second question? Is there a way to impose a constant heat flux (Neumann boundary condition) on a fix wall/gran? in the code, you can see where I've used a set command (commented out for now), but it always gives me the "no particles have been created" error. are they constant temp only? i know I can make a region become a heat source/sink, but if i'm importing a complex geometry via .stl, that might not work if I don't have the correct .vtk file with it.

Advice?

msandli | Mon, 09/21/2015 - 18:09

Any updates on my second

Any updates on my second question? I got my "no particles have been created" error fixed, but I still don't get any heat transfer when I use a set heatSource command on a fix wall/gran

anandmds | Tue, 03/29/2016 - 12:25

Hey msandli,

How did you fix the problem of "-NaN" ?? my heat flux and temperature are "-nan" after a few seconds of running simulation. How do I fix it ??

Thanks & Regards
Anand