Convection induced by composition gradients in miscible systems

When two miscible fluids, such as glycerol (glycer-in) and water, are brought in contact, a large concentration (and density) gradient exists, which relaxes through diffusion. With a mathematical model based on the Korteweg stress, we show that convection can occur which is analogous to surface-tension induced convection (STIC) or Marangoni convection. Specifically. we show that with realistic parameters significant flows can occur with plane interfaces and that drops of miscible fluids can act like their immiscible counterparts. Regarding plane interfaces. an experimental confirmation of this phenomenon is planned for the International Space Station.