Hi,

I have a basic question. I was wondering if anyone could please let me know its answer.

we know that the atoms interact with each other according to a force-field based on namely LJ potential but there is not any viscous force that reduce the relative velocity of pairs. So, if we apply an external force along the nano channel, we expect that the atoms accelerate and their velocities increase infinitely. I wanna know what is the origin of formation of a Poiseuille velocity profile and not a plug flow?

Thank you

AMd

Viscosity results from elastic collisions. Computations from the kinetic theory of gases gives even sensible values, if not accurate.

 

Elastic collisions mean that energy is conserved.

 

Spreading the well-ordered velocity into disordered speed means that flow power converts into heat, through viscosity, and entropy increases.

Thanks for your consideration. As you mentioned before, the quantity of viscosity results from the elastic conservative forces. but I have written a simple MD code in which the viscosity is obtained acceptably after statistical averaging but in presence of the wall I see a plug flow and not a Poiseuille profile. In your opinion, what is wrong?