In small rocky planets, the interplay between pressure and temperature profiles may cause the iron-rich liquid core to solidify from the outer boundary inward. As pure iron crystals form, they are denser than the surrounding liquid mixture. Consequently, they sink into the core before remelting at greater depth due to the increasing temperature. This process is thought to sustain compositional convection which drives a dynamo in the core. Recent parameterisations of these flows disregard the influence of the particle size.
To investigate this convection, a recent paper co-authored by Dr Quentin Kriaa presents the results of a series of analogue laboratory experiments. Sugar grains (analogous to iron crystals) were continuously sieved above a water tank (analogous to the liquid iron-rich core). Through drag and the deposition of dissolved sugar in their wake, these particles sustain a plume, whose properties depend largely on the particle size, as presented in a paper recently published in the Journal of Fluid Mechanics, here. These experiments can inform parameterisations of convection of particle transport in the core, with direct consequences on the possible emergence of a dynamo.