Related Experiment Video
Updated: May 15, 2026
08:27
Aqueous Droplets Used as Enzymatic Microreactors and Their Electromagnetic Actuation
Published on: August 28, 2017
Ultra-quick dynamics and acrobatics of viscous marbles
Auriane Huyghues Despointes1, Yui Takai1,2, Shoko Ii1
1Physique et Mécanique des Milieux Hétérogènes, UMR 7636 du CNRS,PSL Research University, ESPCI, Paris, France.
Nature Communications
|May 13, 2026
Summary
Non-wetting viscous drops move surprisingly fast. A new threshold in driving force causes a tenfold speed increase due to dynamic contact reduction, enhancing mobility.
Area of Science:
- Fluid dynamics
- Soft matter physics
Background:
- Non-wetting viscous drops exhibit high speeds due to minimal substrate contact and internal dissipation.
- Previous models and experiments did not fully capture the dynamics at higher driving forces.
Purpose of the Study:
- To investigate the behavior of non-wetting viscous drops beyond previously studied limits.
- To identify the mechanism behind the significant speed increase observed at a critical driving force threshold.
Main Methods:
- Theoretical modeling of drop dynamics under varying driving forces.
- Experimental observation of fast-revolving drop behavior.
Main Results:
- A critical driving force threshold was identified, leading to a tenfold increase in drop speed.
- This speed enhancement is attributed to a dynamic reduction in contact area.
- The dynamics become non-stationary due to geometrical transformations of the rapidly rotating drops.
Conclusions:
- Viscosity plays a paradoxical role, enabling faster dynamics by slowing contact equilibration and reducing substrate interactions.
- The findings reveal a new regime of non-wetting drop motion with potential implications for microfluidics and material science.
Related Concept Videos
01:15Elastic Collisions: Case Study
Elastic collision of a system demands conservation of both momentum and kinetic energy. To solve problems involving one-dimensional elastic collisions between two objects, the equations for conservation of momentum and conservation of internal kinetic energy can be used. For the two objects, the sum of momentum before the collision equals the total momentum after the collision. An elastic collision conserves internal kinetic energy, and so the sum of kinetic energies before the collision equals...
01:00Elastic Collisions: Introduction
An elastic collision is one that conserves both internal kinetic energy and momentum. Internal kinetic energy is the sum of the kinetic energies of the objects in a system. Truly elastic collisions can only be achieved with subatomic particles, such as electrons striking nuclei. Macroscopic collisions can be very nearly, but not quite, elastic, as some kinetic energy is always converted into other forms of energy such as heat transfer due to friction and sound. An example of a nearly...
01:19Viscosity of Fluid
Viscosity measures the resistance a fluid offers to flow and deformation. It results from internal friction between layers of fluid moving relative to one another. Dynamic viscosity, denoted by the Greek letter mu (μ), quantifies the force needed to move one fluid layer over another. For Newtonian fluids like water and air, the relationship between the shearing stress and the rate of shearing strain is linear, meaning their viscosity remains constant regardless of the applied stress.
02:57Surface Tension, Capillary Action, and Viscosity
Surface Tension
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
01:26Kinetic Friction
Consider a truck trying to pull a stationary car. As the truck exerts a force on the car, static friction is created at the point of contact between the two surfaces. This frictional force resists the car's movement and keeps it at rest. However, when the applied force by the truck surpasses the limiting static frictional force, an interesting phenomenon occurs. The frictional force at the interface reduces to a lower value, known as the kinetic frictional force. At this point, the car begins...
01:17Viscosity
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...