compute heat/flux

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1

Hi, I am using compute heat/flux to check the heat rate in and out of the group of atoms is same or not.

I am using fix ave/time to save the c_heatflux[1] c_heatflux[2] c_heatflux[3] each 100 step:

fix heatflux1 CNTshell ave/time 1 100 100 c_hf1[1] c_hf1[2] c_hf1[3] ave one file heatflux1.dat

However, the vector magnitude sqrt[(c_hf1[1])^2 + (c_hf1[2])^2 + (c_hf1[3])^2] is not consistent.

How can I use it to check the energy amount in and out of a slab is same? Thanks.

Houcoeng
12/08/15

2

What does “not consistent” mean? If the components
are nearly 0.0, I think that means there is no net flux
in or out.

Steve

3

Hi, Steve, last time I confused you. The components are not nearly zeros. Also, what I am trying to do is to check the net flux amount out of the slab by this command, is this possible? Maybe ave/time command to save the data at this point is not working at such case.

Best,
Haoxiang Huang

4

Hi, Steve, last time I confused you. The components are not nearly zeros.
Also, what I am trying to do is to check the net flux amount out of the slab
by this command, is this possible? Maybe ave/time command to save the data
at this point is not working at such case.

nobody can say anything meaningful without having detailed information.
just quoting a few lines of LAMMPS input without knowing the exact
setup, and process of equilibration and whatever else you are doing in
your simulation, is not telling much. there have *lots* of things that
can go wrong and taint your results that have nothing to do with the
commands you have quoted.

LAMMPS commands do what their documentation says it does. if you can
construct a verifiable test case that shows a discrepancy between the
documentation and the implementation, people will look at it. there is
no value in speculation like you are doing it.

axel.

5

I’m CCing Reese Jones who has worked with compute heat/flux for thermal

conductivity calculations. I think it is possible to use is for the instantaneous

energy leaving/entering a group of atoms. Maybe integrating that over time

gives the quantity you are looking for.

Steve