# Relationship between Characteristic Lengths and Effective Saffman Length in Colloidal Monolayers near a Water-Oil Interface

## TL;DR

This study experimentally investigates how hydrodynamic interactions in colloidal monolayers near a water-oil interface are characterized by anisotropic characteristic lengths, revealing universal behavior through effective Saffman length analysis.

## Contribution

The paper introduces an experimental method to measure characteristic lengths in colloidal monolayers near a liquid-liquid interface and relates these to hydrodynamic interactions using an effective Saffman length.

## Key findings

- Characteristic lengths are anisotropic near the interface.
- Universal master curves describe cross-correlated diffusion.
- Hydrodynamic interactions are effectively characterized by the Saffman length.

## Abstract

The hydrodynamic interactions (HIs) in colloidal monolayers are strongly influenced by the boundary conditions and can be directly described in terms of the cross-correlated diffusion of the colloid particles. In this work, we experimentally measured the cross-correlated diffusion in colloidal monolayers near a water-oil inter-face. The characteristic lengths of the system were obtained by introducing an effec-tive Saffman length. The characteristic lengths of a particle monolayer near a water-oil interface were found to be anisotropic in the longitudinal and transverse directions. From these characteristic lengths, the master curves of cross-correlated diffusion are obtained, which universally describe the HIs near a liquid-liquid interface.

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Source: https://tomesphere.com/paper/1812.10712