Abstrakt
Core formation, crystal/melt separation, mingling of immiscible magmas,and diapirism are fundamental geological processes that involve differential motions driven by gravity. Diffusion modifies the composition or/and temperature of the considered phases while they travel.
Solid particles, liquid drops and viscous diapirs equilibrate while sinking/rising through their surroundings with a time scale that depends on the physics of the flow and the material properties. In particular, the internal circulation within a liquid drop or a diapir favors the diffusive exchange at the interface.
To evaluate time scales of chemical/thermal equilibration between a material falling/rising through a deformable medium, we propose analytical laws that can be used at multiple scales. They depend mostly on the non-dimensional Peclet and Reynolds numbers, and are consistent with numerical simulations.