Morphological Instabilities in Flows with Cooling, Freezing or Dissolution

Abstract

The Earth's crust is shaped by a wide range of fluid flows and their characteristic instabilities. Here we consider the flow of silicate melts, either within the crust or as surface lava flows, and the way in which these flows are affected by variable viscosity due to cooling or by a yield strength resulting fromsolidification. These effects invariably lead to non-uniformor three-dimensional flow patterns, particularly fingering and channelisation. In the case of solidifying free-surface flows there is, in addition, a range of three-dimensional surface structures or deformation styles depending on flow conditions. Parallels can be drawn with channeling instabilities that occur in either the dissolution of a porous matrix or precipitation reactions within a matrix during the percolation of an interstitial fluid.