"LIGGGHTS WWW Site"_lws - "LIGGGHTS Documentation"_ld - "LIGGGHTS Commands"_lc :c

:link(lws,http://www.cfdem.com)
:link(ld,Manual.html)
:link(lc,Section_commands.html#comm)

:line

fix heat/gran command :h3

[Syntax:]

fix ID group-ID heat/gran T0 :pre

ID, group-ID are documented in "fix"_fix.html command
heat/gran = style name of this fix command
T0 = initial (default) temperature for the particles :ul

[Examples:]

fix 3 hg heat/gran 273.15 :pre

[LIGGGHTS vs. LAMMPS info:]

This command is not available in LAMMPS.

[Description:]

Calculates heat conduction between particles in contact and temperature update according to 

:c,image(Eqs/heat_gran.png)

It is assumed that the Temperature within the particles is uniform. 
To make particles adiabatic (so they do not change the temperature), 
do not include them in the fix group. However, heat transfer is calculated 
between particles in the group and particles not in the group (but 
temperature update is not performed for particles not in the group).
Thermal conductivity and specific thermal capacity must be defined for 
each atom type used in the simulation by means of 
"fix property/global"_fix_property.html commands:

fix id all property/global thermalConductivity peratomtype value_1 value_2 ... 
(value_i=value for thermal conductivity of atom type i) :pre

fix id all property/global thermalCapacity peratomtype value_1 value_2 ...
(value_i=value for thermal capacity of atom type i) :pre

To set Temperature for a group of particles, you can use the set command 
with set keyword: 'property/atom' and set values: 'Temp T'. T is the 
temperature value you want the particles to have. To set heat sources 
(or sinks) for a group of particles, you can also use the set command 
with the set keyword: 'property/atom' and the set values: 'heatSource h'. 
h is the heat source value you want the particles to have (in Energy/time 
units). A negative value means it is a heat sink. Examples would be: 

set region halfbed property/peratom Temp 800.
set region srcreg property/peratom heatSource 0.5 :pre

Area correction:

Fix heat/gran can perform an area correction to account for the fact 
that the Young's modulus might have been decreased in order to speed-up 
the simulation. This area correction is activated by specifying the original 
Young's modulus of each material by means of a fix_property_global command:

fix id all property/global youngsModulusOriginal peratomtype value_1 value_2 ... 
(value_i=value for original Young's modulus of atom type i) :pre

This area correction is performed by scaling the contact area with 
(Y*/Y*,orig)^a, where Y* and Y*,orig are calculated as defined in pair gran. 
The scaling factor is given as a=1 for pair/gran/hooke/* and a=2/3 for 
pair/gran/hertz/*.

[Output info:]

You can visualize the heat sources by accessing f_heatSource\[0\], and the 
heatFluxes by f_heatFlux\[0\] . With f_Temp\[0\] you can access the per-particle 
temperature. You can also access the total thermal energy of the fix group 
(useful for the thermo command) with f_id .


[Restart, fix_modify, run start/stop, minimize info:]

The particle temperature and heat source is written is written to 
"binary restart files"_restart.html so simulations can continue properly. 
None of the "fix_modify"_fix_modify.html options are relevant to this fix.

This fix computes a scalar which can be accessed by various "output
commands"_Section_howto.html#4_15.  This scalar is the total thermal energy
of the fix group

No parameter of this fix can be used with the {start/stop} keywords of
the "run"_run.html command.  This fix is not invoked during "energy
minimization"_minimize.html.

[Restrictions:] 

Area correction currently only works with pair styles pair/gran/hooke/* and pair/gran/hertz/*

[Related commands:]

"compute temp"_compute_temp.html, "compute
temp/region"_compute_temp_region.html

[Default:] none

