Water flow in Nanochannel: Pressure calculation

Hi all

I have been trying to simulate water flow (SPC/E) in a rectangular nano-channel with side walls (Explicit walls with LJ interactions). The simulation looks fine in VMD. But the value of pressure is really huge. Im using real units and pressure is ~1000s of atm.
Also when I calculated flow pressure using compute stress/atom command (group flow contains only water) its value is huge and negative. What might be the reason?
I actuated the flow by applying a gravity on water molecules.

Please share if there is anything in particular which I should keep in mind while simulating such systems.
Im using LAMMPS-12Feb14 version

Thanks in advance


Sreehari P D

Masters Student in Thermal Science and Engineering
Department of Mechanical Engineering
Indian Institute of Technology Kharagpur

Kharagpur, West Bengal, India

The compute pressure and compute stress/atom calcs include
a kinetic component. If the atoms are flowing, you probably
want to exclude their flow velocity. As the doc pages explain
you can assign a temperature compute for the kinetic term
that excludes a “bias” like the flow.