Molecular Fluid Dynamics

Molecular fluid dynamics, that is the simulation of fluids using molecules, has enormous potential. The predominant approach in fluid dynamics research is continuum based simulation, in part because this it taught in most undergraduate course. The history of continuum fluid dynamics goes back to the birth of the calculus and given the widespread scepticism for the existence of atoms, has largely ignored anything outside this paradigm. However, within the chemistry community, the advent of computers allowed simulations beyond thermodynamic equilibrium. This field became know and non-equilibrium molecular dynamics, the equilibrium referred to here being that of thermodynamics. The progress made has been great, but the potential for fundamental insight into fluid dynamics has only just started to be explored.

Through molecular dynamics we can explore the origins of turbulence from molecular instability, as well as what happened when we reach the bottom of the turbulent energy cascade. We have exact energy conservation and reversible equation, allowing insights into the second law of thermodynamics and its part in our understanding of dissipation. Through molecular simulation, we model the structure of a liquid, so the viscosity is an output of the simulation resulting from the evolution of this molecular structure. The liquid remembers its state and this has a direct bearing on the future evolution of this complex chaotic system. The formation of bubbles (nucleation) is a natural consequence of heating in a molecular system. We can model rough wall and understand where the slip boundary condition comes from, explore the fluctuating nature of a liquid-vapour interface or include complex chemical structure and see how the fluid properties change.