Controlling the Motion

Civic planners and schoolteachers have long appreciated that the motion of cars on highways or children through hallways proceeds smoothly if lanes of traffic are formed. Truskett's research team found that a similar principle applies for the motion of fluid particles in narrow channels. Specifically, their computer simulations reveal that fluid particles move past one another more easily if they first form "layers" aligned with the boundaries of the channels.

The team has also introduced a way to systematically determine which types of channel boundaries will promote or frustrate the formation of the layers necessary for faster particle transport.

If layering leads to faster particle dynamics, it is natural to ask why bulk fluids adopt a more disordered structure with no layering, said the scientists. “The reason: thermodynamics determines the structure of a fluid, not dynamics - and thermodynamics favors a disordered state for bulk fluids because it lowers the system's free energy,” they said.

The team determined that confining a fluid to small length scales allowed them to tune the thermodynamically-favored state to coincide with one that has layering and fast particle dynamics.; Source: University of Texas