Experimental Fluid Dynamics - Dr. Michael Cawley

The experimental fluid dynamics group at Maynooth University uses a variety of approaches to investigate the behaviour of water and aqueous solutions in the vicinity of the density anomaly, which in pure water at a pressure of one atmosphere occurs close to 4°C. The majority of fluids expand when heated, which gives rise to standard convective heat transfer. Pure water contracts when heated from 0°C to 4°C, at which point it passes through a maximum value of its density. Above 4°C, water expands in the normal manner. The reason for this anomalous behaviour is not as yet well understood, and the implications for convective flow and heat transfer are still being discovered.

At Maynooth University, for example, a simple device has been developed which exhibits partial heat rectification in the presence of the density anomaly (i.e. different rates of heat transfer pass through the system depending on the orientation of the temperature gradient.) A sensitive technique has also been devised to detect and track the temperature of maximum density in aqueous solutions as a function of solute nature and concentration. It is found that while most solutes cause the temperature of maximum density to decrease, some solutes (the monohydric alcohols) may initially cause the temperature of maximum density to rise. None of the current molecular models of water can explain all of these observations. It is planned to extend the experimental investigations of the density anomaly by introducing pressure changes to rapidly scan through the point of maximum density.

The experimental investigations are complemented by computer modeling using both a commercial finite element solver (Comsol Multiphysics) and customised computational fluid dynamics software.

Post-graduate research

Students with further queries regarding research or applications for M.Sc. or Ph.D. on this topic should contact Dr. Michael Cawley.