Spatial profile of heat flux

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1

Dear LAMMPS users,

I am trying to dump the spatial profile of the heat flux with the command ave/chunk.

This command does not work because: “Fix ave/atom does not calculate per-atom values”.

Is there a way to convert a per-atom value quantity so that fix ave/atom can calculate it?

Here is part of my script

compute myKE all ke/atom
compute myPE all pe/atom
compute myStress all stress/atom NULL virial
compute flux all heat/flux myKE myPE myStress

variable Jx equal c_flux[1]/vol
variable Jy equal c_flux[2]/vol
variable Jz equal c_flux[3]/vol

compute layers all chunk/atom bin/1d x 0. {Dz} 0.05 units reduced fix 2 all ave/chunk {Ne} {Nr} {Nf} layers c_flux[1] file profile.heat

Thank you,

Abdou

2

Dear LAMMPS users,

I am trying to dump the spatial profile of the heat flux with the command
ave/chunk.

This command does not work because: "Fix ave/atom does not calculate
per-atom values".

​your inquiry makes no sense. there is _no_ fix ave/atom in the commands
you quoted below, so none of those commands can be the cause of the error
you are reporting.
​
axel.

3

Sorry for that mistake. I’ve been trying many things since this morning, including fix ave/tom which works for the stress but not for the heat flux.

When I tried this code (this only part of my script),

compute myKE all ke/atom

compute myPE all pe/atom

compute myStress all stress/atom NULL virial

compute flux all heat/flux myKE myPE myStress

variable Jx equal c_flux[1]/vol

variable Jy equal c_flux[2]/vol

variable Jz equal c_flux[3]/vol

compute layers all chunk/atom bin/1d x 0. ${Dz} 0.05 units reduced

fix 2 all ave/chunk {Ne} {Nr} ${Nf} layers c_flux[1] file profile.heat

I got this error: " Error: Illegal compute chunk/atom command
Last command: compute layers all chunk/atom bin/1d x 0. ${D} units reduced"

What is the right way to dump the spatial profile of the heat flux (x, Jx) ?

Abdou

4

Sorry for that mistake. I’ve been trying many things since this morning, including fix ave/tom which works for the stress but not for the heat flux.

When I tried this

compute myKE all ke/atom

compute myPE all pe/atom

compute myStress all stress/atom NULL virial

compute flux all heat/flux myKE myPE myStress

variable Jx equal c_flux[1]/vol

variable Jy equal c_flux[2]/vol

variable Jz equal c_flux[3]/vol

compute layers all chunk/atom bin/1d x 0. ${Dz} 0.05 units reduced

fix 2 all ave/chunk {Ne} {Nr} ${Nf} layers c_flux[1] file profile.heat

I got this error: " Error: Illegal compute chunk/atom command
Last command: compute layers all chunk/atom bin/1d x 0. ${D} units reduced"

What is the right way to dump the spatial profile of the heat flux (x, Jx) ?

Abdou

5

Sorry for that mistake. I've been trying many things since this
morning, including fix ave/tom which works for the stress but not for the
heat flux.

When I tried this code (this only part of my script),

compute myKE all ke/atom
compute myPE all pe/atom
compute myStress all stress/atom NULL virial
compute flux all heat/flux myKE myPE myStress

variable Jx equal c_flux[1]/vol
variable Jy equal c_flux[2]/vol
variable Jz equal c_flux[3]/vol

compute layers all chunk/atom bin/1d x 0. \{Dz\} 0\.05 units reduced fix 2 all ave/chunk {Ne} \{Nr\} {Nf} layers c_flux[1] file
profile.heat

I got this error: " Error: Illegal compute chunk/atom command
                         Last command: compute layers all chunk/atom
bin/1d x 0. ${D} units reduced"

​this error is also not consistent with the quoted​ input script code.

axel.

6

Here is the error:

ERROR: Fix ave/chunk compute does not calculate per-atom values (…/fix_ave_chunk.cpp:293)
Last command: fix 22 all ave/chunk {Ne} {Nr} ${Nf} layers c_flux[1] file profile.heat

My script file is attached. The lines that do not seem to work are:

compute layers all chunk/atom bin/1d x 0. {Dz} units reduced fix 22 all ave/chunk {Ne} {Nr} {Nf} layers c_flux[1] file profile.heat

in.MOD (3.65 KB)

7

Here is the error:

ERROR: Fix ave/chunk compute does not calculate per-atom values
(../fix_ave_chunk.cpp:293)
Last command: fix 22 all ave/chunk \{Ne\} {Nr} ${Nf} layers
c_flux[1] file profile.heat

​yes, and the error message is correct since c_flux is not a per-atom
property, but a global vector. you *must* use a per-atom compute for being
able to use fix ave/chunk.

axel.

8

Thank you Axel.

So here is what I am trying do, and any help or suggestion would be very welcome.

I want to see how the heat flux evolves spatially. That is why I used fix ave/chunk but as you mentioned c_flux is not a per-atom property therefore it can’t be used with this command.

Is there something else I can use to obtain the heat flux profile? How could I compute a per-atom property heat flux or convert the global quantity I already have to a per-atom property?

Abdou

9

Thank you Axel.

So here is what I am trying do, and any help or suggestion would be very
welcome.

I want to see how the heat flux evolves spatially. That is why I used fix
ave/chunk but as you mentioned c_flux is not a per-atom property therefore
it can't be used with this command.

Is there something else I can use to obtain the heat flux profile? How
could I compute a per-atom property heat flux or convert the global
quantity I already have to a per-atom property?

​you would have to write a custom compute heat/flux/atom style yourself.

axel.

10

Alright. Thank you.

Abdou