Coupling of Cooling, Solidification and Gravity-driven Flow

The gravity-driven spread of fluids with a free surface can be strongly influenced by solidification of the fluid when it experiences heat loss from its surface and is cooled below its solidification temperature. Examples of interplay between heat loss, solidifica- tion and flow are found in lava flows, which take on many morphologies depending on the fluid properties and flow conditions. Laboratory experiments with viscous polyethylene glycol wax and yield-strength slurry flows under cold water have been useful in rationalising observed morphological types in terms of dynamical regimes depending on cooling rate and extrusion rate. Scaling analyses have also achieved some success in predicting the spreading rates of solidifying flows on both a horizontal floor and a sloping plane.