|Fluid Mechanics and Heat Transfer
1. Hydrodynamic stability of two-phase flows
Our group has been investigating the interfacial stability of certain two-phase flows that occur in secondary oil recovery, in the lung alveoli and in ink–jet printing. Both the linear and non-linear stabilities of these problems are being investigated theoretically. An experimental setup with a fast video camera (1000 frames/sec.) is being used to observe unstable events.
2. The mechanism of heat transfer in boiling
It has been known for half a century that the heat transfer from a stove through the metal and thin layer of fluid near it in a pot of water grows gradually as one superheats the fluid, but abruptly increases by between one to two orders of magnitude when microscopic vapor bubbles appear at the solid-liquid interface. Literature discussion of this phenomena centers on increased convection bringing cold fluid closer to the hot metal and on transport through a supposed micro-fluid layer between the bubble and the solid surface. Numerical methods for calculating the quasi-steady heat transfer due to conduction in such a system show that the change introduced by the presence of the vapor bubble at the solid-liquid interface can account for much of the observed change in heat flux. The calculation is being refined to include effects ignored to date by the use of better empirical models and by use of molecular dynamics, with more physically based models.