Gravity currents at work and in the kitchen

Abstract:

Gravity currents occur frequently in many household, industrial and environmental situations whenever fluid of one density intrudes into fluid of a different density. Common examples include: waterpouring over the floor; honey flowing over toast, river discharges into reservoirs or the sea; the outflow of the Mediterranean waters into the Atlantic; turbidity currents; sea breezes; snow avalanches; pyroclastic flows from volcanic eruptions; rock falls; oil spills over either land orsea; and sequestered carbon dioxide intruding into a saline aquifer at depth.

The talk will briefly review the fundamental concepts and mathematics behind the motion of gravity currents: at high and low Reynolds number; when the density difference is due to (relatively heavy) particles, which fall out of the flow; and the flow in porous media. Some of the phenomena will be illustrated by simple desk-top experiments; others by video footage.