Modeling cooling due to heat transfer with walls

Dear all,

the following question has must to do with MD concepts than with LAMMPS itself, but since I think you can help me I ask it here :slight_smile:

I am interested in modeling how a wall at a fixed temperature (300K) cools a polymer initially at a higher temperature down to the walls temperature of 300K.

For doing so I have defined an atomistic wall that consists on a FCC Fe structure.

As fas as I know, I have to thermostat the wall. I am currently doing this via a Langevin thermostat and NVE for time integration.

The movement of the polymer through the wall is modeled via an aveforce command and a NPT thermostat.

Is all of the above an acceptable approach? Could you give me some insight on how to approach it?

Thanks in advance.

Dear all,

I am struggling with this problem without success.

Initially I have the polymer above a FCC structure. The FCC structure has a hole in which I want to introduce the polymer.

image.00100.jpg

First of all I minimize the polymer structure and next to it I run an equilibration run:

Dear all,

I have discovered that by changing the command:

fix 6 polymer_group addforce 0 0 -3

for

fix 6 polymer_group addforce 0 0 -0.0001

The error doesn’t appear, however, I don’t observe any cooling of the polymer due to heat transfer with the walls.

image.00100.jpg

Dear all,

I have discovered that by changing the command:

fix 6 polymer_group addforce 0 0 -3

for

fix 6 polymer_group addforce 0 0 -0.0001

The error doesn't appear, however, I don't observe any cooling of the
polymer due to heat transfer with the walls.

have you made an estimate of what amount of energy would be
transferred for the duration of your simulation?

axel.