Overview

A rigorous, first-principles based understanding of complex fluids and interfaces is a necessary pre-requisite to formulate the macroscopic rheology of complex fluids, and to describe interfaces in a physically useful and mathematically consistent manner.

The IUTAM symposium on the Dynamics of Complex Fluids and Interfaces aims to bring together leading researchers to discuss recent developments and future challenges in:

1. Complex fluids: Rheology and stability of flows of grains, polymers and suspensions.
2. Interfaces (a) between fluids and soft solids, and (b) driven by phase change.

Background & Motivation

Complex fluids (e.g. polymers, grains, etc.) are of much interest to engineers, physicists, and mathematicians. At the same time, fluids interact with the environment, other complex fluids, or with soft and highly deformable solids across interfaces. Sometimes, the interface is a site for phase change, and is influenced by dissolved solutes. Such interfaces are complex in nature, and not all the physics has been unraveled, e.g. is interfacial tension uniquely defined at a soft solid-liquid interface?

A fundamental challenge in complex fluids arises due to inter-particle interactions, which leads to a, generally intractable, `many-body’ problem. Often, such interactions are mediated by a background fluid, or affected by a boundary. Then there are possibilities such as the transitioning of colloidal suspensions to granular suspensions, where lubricated inter-particle contacts are replaced by frictional contacts. These aspects make the description of complex fluids very challenging.

Interfaces in simpler systems (e.g. gas-liquid) are well understood, but interfaces involving a complex fluid and another medium less so. The microstructural length scale in the complex fluid may become comparable to the scale characterizing interfacial thickness, and this may introduce discontinuities in fields across the nominal interface. Sometimes, the interface itself has to be treated as a separate continuum.

Thus, both complex fluids and interfaces require understanding founded on first principles, and constitute the main goal for this IUTAM symposium.