Question about fix edpd/source and defining the heat source coordinates

Hi everybody,

I am trying to add a heat source to my edpd coarse graining model .

Following the recommended inputfile example provided by one of the eDPD authors, a block has been defined at a region ( -10<x<10, -10<y<10, -5<z<5),

having in mind that the heat source values for a cuboid based on LAMMPS documentation is defined as

cuboid values = cx,cy,cz,dLx,dLy,dLz,source
cx,cy,cz = x,y,z lower left corner of a cuboid domain (distance units)
dLx,dLy,dLz = x,y,z side length of a cuboid domain (distance units)
source = heat source or concentration source (flux units, see below).

Looking at the following edpd example:

########################################################################

Heat conduction analog of periodic Poiseuille flow problem

using energy-conserving DPD (eDPD) simulation

Created : Zhen Li ([email protected])

Division of Applied Mathematics, Brown University.

mDPD system setup follows Fig.12 in the publication:

Z. Li, Y.-H. Tang, H. Lei, B. Caswell and G.E. Karniadakis.

"Energy-conserving dissipative particle dynamics with

temperature-dependent properties". J. Comput. Phys.,

2014, 265: 113-127. DOI: 10.1016/j.jcp.2014.02.003

########################################################################
units lj
dimension 3
boundary p p p
neighbor 0.2 bin
neigh_modify every 1 delay 0 check yes

atom_style edpd

region edpd block -10 10 -10 10 -5 5 units box
create_box 1 edpd
create_atoms 1 random 16000 276438 NULL
mass 1 1.0
set atom * edpd/temp 1.0
set atom * edpd/cv 1.0E5

pair_style edpd 1.58 9872598
#pair_coeff 1 1 18.75 4.5 0.41 1.58 1.45E-5 2.0 1.58
pair_coeff 1 1 18.75 4.5 0.41 1.58 1.41E-5 2.0 1.58 &
power 10.54 -3.66 3.44 -4.10 &
kappa -0.44 -3.21 5.04 0.00

compute mythermo all temp
thermo 100
thermo_modify temp mythermo
thermo_modify flush yes

comm_modify vel yes

velocity all create 1.0 432982 loop local dist gaussian

fix mvv all mvv/edpd 0.5
fix upper all edpd/source cuboid 0.0 5.0 0.0 20.0 10.0 10.0 0.01
fix lower all edpd/source cuboid 0.0 -5.0 0.0 20.0 10.0 10.0 -0.01

timestep 0.01
run 500
reset_timestep 0

compute temp all edpd/temp/atom
compute ccT all chunk/atom bin/1d y 0.0 1.0
fix stat all ave/chunk 1 500 500 ccT c_temp density/number norm sample file temp.profile

run 500

the lower left corner of the heating region is located at x=0.0 y=5.0 z=0.0 , with (dl_x=20.0 dl_y=10.0 and dl_z= 10.0), which means that the cuboid coordinates are ( 0<x<0+20, 5<y<5+10, 0<z<0+10). This heating cuboid with mentioned coordinate cannot fit into the block region and falls outside the defined block region (-10 10, -10 10, -5 5). I want to know what is the logic behind it or if I am thinking wrong?

I suspect that the only person that can answer your question with authority, is the person that created the example input deck. There is contact info included, but be aware that people in academia might change affiliation, so you may need to do some web search. I often had success tracking down people’s updated affiliation from their publications listed on Google Scholar.

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