Melting and dissolution across scales in multicomponent systems

Introduction

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.

Examples of Large-Scale Effects

On large scales, a relevant example for the climate is glaciers and icebergs melting into the ocean. Here, 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, phoretic forces along the interfaces also come into play.

Microscale Dynamics

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.

Challenges in Understanding

In spite of the relevance for these and many other applications, such multicomponent, multiphase systems with melting or dissolution phase transitions are poorly understood. This is due to their complexity, multiway coupling, feedback mechanisms, memory effects, and collective phenomena.

Project Objective

The objective of this project is a true scientific breakthrough: We want to achieve a quantitative understanding of melting and dissolution processes in multicomponent, multiphase systems, across all scales and on a fundamental level.

Methodology

To achieve this, we will perform a number of key controlled experiments and numerical simulations for idealized setups on various length scales, inspired by the problems outlined above. This approach will allow for a one-to-one comparison between experiments and numerics/theory.

Expected Outcomes

For the first time, we will perform local measurements of velocity, salt concentration, and temperature and connect them to global transport processes. This will enable us to arrive at a fundamental understanding of such Stefan problems in multicomponent systems.