Dynamics of complex fluids

How can we make agricultural spraying more effective while reducing its environmental impact? Tiny droplets can drift away in the wind, while others bounce straight off plant leaves. Understanding how complex fluids behave offers new ways to tackle both challenges.

In the Soft Matter group, we combine high-speed imaging, fluid mechanics, and rheology to explore how polymers, surfactants, and emulsions influence droplet formation, impact, and flow. Our research connects fundamental fluid physics with smarter spray formulations.

01 / SPRAY FORMATION
Bigger droplets, less drift

We investigate how polymer additives alter liquid-sheet breakup and droplet size, helping reduce spray drift while maintaining effective coverage.

02 / DROPLET IMPACT
Making droplets stick

By studying droplet impacts on water-repellent surfaces, we reveal how dynamic surface tension controls spreading, retraction, and bounce-off.

03 / COMPLEX FLUID PHYSICS
When liquids behave differently

From stretching polymer filaments to stabilising emulsions, we uncover how elasticity, flow history, and interfacial interactions shape fluid behaviour.

Research Highlights

Selected publications from our work on sprays, droplet impact, and polymer dynamics.

SPRAY PHYSICS  ·  2022
What determines the drop size in sprays of polymer solutions? ↗

A. Gaillard, R. Sijs & D. Bonn · Journal of Non-Newtonian Fluid Mechanics

Revealing how polymer elasticity changes spray breakup and produces larger droplets with the potential to reduce drift.

POLYMER DYNAMICS  ·  2025
When does the elastic regime begin in viscoelastic pinch-off? ↗

A. Gaillard et al. · Journal of Fluid Mechanics

Identifying the critical moment when polymer elasticity begins to dominate the thinning and breakup of liquid filaments.

DROPLET DEPOSITION  ·  2021
Controlling droplet deposition with surfactants ↗

H. Hoffman, R. Sijs, T. de Goede & D. Bonn · Physical Review Fluids

Demonstrating why the rapidly changing surface tension of droplets is crucial for efficient wetting and deposition.

Research contact: Daniel Bonn  ·  d.bonn@uva.nl ↗

Postal Adress

Van der Waals-Zeeman Instituut
University of Amsterdam
P.O. Box 94485
1090 GL Amsterdam

Visit us

Science Park 904
C4.238 (4th floor)
1098 XH Amsterdam
The Netherlands

Contact us

Phone: +31 (0)20 525 6311
Fax:      +31 (0)20 525 5102
Email:   secr-iop-science(at)uva.nl