Rain drops on a windshield. Dew on the grass. Penicillin on the tip of a needle. We regularly see a liquid in contact with a solid, unaware that this common occurrence depends on a complicated behavior invisible to the naked eye. Yet this behavior, once understood, can be leveraged to enable improvements in biofluid mechanics, petroleum engineering, and other scientific fields.
The perspectives of how a large amount of fluid behaves on a surface, and how it behaves at the molecular level, are quite different. For example, a polymeric fluid may seem to be glued in place on a hard surface, but numerical experiments such as Dr. Priezjev’s reveal that each polymer chain engages in a complicated maneuvering of unwrapping and tumbling, allowing the fluid to move with slip at the interface (examples of computer animations and their descriptions are presented on the research web page). The degree of slip depends sensitively on both the type of fluid and wall examined.
To understand the molecular motion of a fluid, Dr. Priezjev runs extensive molecular dynamics simulations. He performs these simulations through the High Performance Computing Center (HPCC) facility, calling it “a luxury that the university maintains”, leaving more time for his own research without the headache of managing his own computing cluster. Experimentally, it is exceedingly difficult to extract information about the molecular motion very close to a solid boundary, so numerical simulations allow researchers to take measurements of the molecules’ positions and velocities and to resolve velocity profiles at the interface. According to Dr. Priezjev, the HPCC is crucial to his research.
Dr. Priezjev carries out research in microfluidics at MSU since 2005, but he has not always focused his studies on fluid flows. From a small scientific town outside of Moscow, he originally studied physics at the Joint Institute for Nuclear Research. It wasn’t until his graduate studies at Brown University that he began to study complex fluids. He says that he likes the visual aspect of the stimulations and the ability to understand what happens in a system at the molecular level, and for several years has been interested in studying various aspects of interfacial phenomena including the motion of a contact line, slip boundary conditions, and the development of the hybrid multiscale methods for fluid flows.
The research Dr. Priezjev performs in the HPCC helps him to model fluid flow in microfluidic systems. The results of such research are relevant to the oil extrusion from porous materials or it may help the development of devices that will aid in disease diagnosis or used for the drug delivery. The behavior of the tiniest drops of fluid at the surface is something that can potentially affect us all in a monumental way.
