PhD positions - Melting & dissolution across scales in multicomponent systems

Melting and dissolution induce temperature and concentration gradients in liquid systems. These gradients induce flows, namely buoyancy driven flows on large scales and phoretic flows on small scales. Such flows locally enhance or delay the melting or dissolution process and thus determine the objects’ shape. On large scales, a relevant example for the climate are glaciers and icebergs melting into the ocean, where cold and fresh meltwater experiences buoyant forces against the surrounding ocean water, leading to flow instabilities, thus shaping the ice and determining its melting rate. Another example is the dissolution of liquid CO2 in brine for CO2 sequestration. Next to buoyant forces also phoretic forces along the interfaces come into play. For dissolving drops at the microscale the phoretic forces become dominant. The resulting Marangoni flow not only affects their dissolution rate, but can also lead to their autochemotactic motion, deformation, or even splitting.

In spite of the relevance for these and many other applications, such multicomponent, multiphase systems with melting or dissolution phase transitions are poorly understood, due to their complexity, multiway coupling, feedback mechanisms, memory effects & collective phenomena. The objective of this project is a true scientific breakthrough: We want to come to a quantitative understanding of melting & dissolution processes in multicomponent, multiphase systems, across all scales and on a fundamental level. To achieve this, we perform a number of key controlled experiments & numerical simulations for idealized setups on various length scales, inspired by above sketched problems, but allowing for a one-to-one comparison between experiments and numerics/theory. For the first time, we will perform local measurements of velocity, salt concentration, and temperature and connect them to global transport processes, to arrive at a fundamental understanding of such Stefan problems in multicomponent systems.

Contact: Prof. Dr. Detlef Lohse (PoF), Assoc. Prof. Dr. Sander Huisman (PoF)

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