Katrina Hay
Current Research Focus:
Pet Physics Project:
A new field in fluid physics is emerging from a curiosity about how the natural world works. This application of fluid physics is being called “Pet Physics” by the media and seeks to answer questions about how animals interact with fluids. These investigations include “cat lapping” and the “wet dog shake.” I use a high-speed camera to capture the fast dynamics of animals interacting with fluids, including the lapping of domestic cats and Sumatran tigers at Point Defiance Zoo and Aquarium. Then I model this interaction experimentally and theoretically. The purpose of pet physics is to better understand how nature works and to apply the most successful concepts to improve current inventions. Animals have adapted to their environments and evolved to use the most efficient methods; industry will do well to imitate many natural processes already known intuitively by animals.

Rock Fracture Project:
The overall goal of our project is to explain fluid transport from the surface to the ground water.  This has industrial and environmental applications, everything from nuclear contaminant flow to pesticides to silver extraction. Before one can model the big picture of multiphase flow in a rock fracture system it is important to understand the basic physics that describes types of fluid movement and interaction with boundaries. In a fractured rock system, the rock surface can be porous, moist, chemically heterogeneous and rough. Focusing on roughness, specific projects include the creation of a theoretical model for the wetting of a rough surface. Theoretical diffusion-type laws based on capillarity and fluid and surface frictional resistive forces are used to predict fluid invasion rates.
This project also includes experimental investigations into multiphase flow in fractured rock systems. These investigations focus on the effect of surface roughness on fluid droplets (or "liquid bridges"). The fluid-solid contact angle is important in the dynamics as it effects the extent of interface curvature and therefore the capillary pressure gradient across the droplet. This gradient can resist or assist the downward droplet motion.  We found that the speed of droplets moving down glass fractures is significantly different than the speed down rock fractures. Experiments are being used to develop predictive relationships to calculate the speed of liquid droplets in unsaturated rock fractures. 

Application:
The study of fluid physics is important for understanding many fluid processes. Many processes in nature can be described by fluid dynamics, including glacier movement, galaxy rotation, ocean currents, atmospheric dynamics, water ingestion of animals and microscopic pore filling in soils and rock.