- Published on 12 October 2022
When a temperature difference, or gradient, is applied over a bulk fluid mixture at equilibrium, the phenomenon known as thermodiffusion, or the Ludwig-Soret effect, may occur. The thermal force will in general cause the components in the mixture to migrate until the thermal force is balanced by concentration gradients. If the thermal force is applied to a colloidal suspension, the colloids drift towards cold or hot regions. This phenomenon is commonly referred to as thermophoresis. If the fluid is soaked in a porous medium, an additional effect known as thermos-osmosis may occur. Thermo-osmosis leads to a pressure difference. These effects are different from normal diffusion and osmosis, where a concentration difference is the driving force.
The complexity of acquiring, understanding, and modeling thermodiffusion is a continuous challenge. Even the sign of the Soret coefficient is hard to predict. Several ternary systems have been measured in recent years, and new results are included in this issue. Systematic selections of components and compositions give trends in the data that show the effects of the components’ chemical nature.
The EPJ E topical issue “Thermal non-equilibrium phenomena in fluid mixtures” includes new results presented at the International Meeting on Thermodiffusion (IMT14) organized by The Norwegian University of Science and Technology, Trondheim, Norway on May 25-27, 2021.
New results on
- Thermodiffusion in multicomponent fluid mixtures and solutions
- Theories and empirical models
- Methodological developments
- Thermophoresis of colloids
- Thermodiffusion in porous systems