Related Experiment Video
Updated: Oct 17, 2025
08:49
Impacts of Free-falling Spheres on a Deep Liquid Pool with Altered Fluid and Impactor Surface Conditions
Published on: February 17, 2019
6.7K
Attractive forces slow contact formation between deformable bodies underwater
Mengyue Sun1, Nityanshu Kumar1, Ali Dhinojwala2
1School of Polymer Science and Polymer Engineering, The University of Akron, Akron, OH 44325.
Summary
Underwater adhesion is surprisingly slow between hydrophobic surfaces due to trapped water. This contrasts with hydrophilic surfaces and impacts soft robotics and biomotion.
Area of Science:
- Physics
- Materials Science
- Tribology
Background:
- Thermodynamics predicts stronger adhesion between hydrophobic surfaces underwater.
- Water's presence affects dynamics of adhesion, including solid deformation and liquid evacuation.
- Underwater adhesion challenges exist in soft robotics, biolocomotion, and tire traction.
Purpose of the Study:
- Investigate underwater contact evolution with high resolution.
- Precisely measure film evacuation dynamics.
- Control surface wettability during contact.
Main Methods:
- High-resolution in situ frustrated total internal reflection imaging.
- Tracking underwater contact between soft-elastic hemispheres and smooth-hard surfaces.
- Varying surface stiffness and wettability.
Main Results:
- Hydrophobic-hydrophobic contact shows water evacuation rates three orders of magnitude slower than hydrophobic-hydrophilic contact.
- A transition in evacuation mode observed around zero thermodynamic adhesion, visualized with 3D height maps.
- Adhesive contact features sealed puddles; nonadhesive contact shows smooth, film-wise evacuation.
Conclusions:
- Underwater adhesive contact dynamics differ significantly from nonadhesive contact.
- Trapped water in adhesive contacts leads to instability and reduced solid-solid contact.
- Findings explain underwater biolocomotion patterns and inform technological applications.
Related Concept Videos
02:57Surface Tension, Capillary Action, and Viscosity
30.6K
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...
30.6K
01:11Buoyancy and Stability for Submerged and Floating Bodies
2.2K
In fluid mechanics, buoyancy and stability are key concepts for understanding the behavior of submerged and floating bodies. When a stationary body is fully or partially submerged in a fluid, the fluid exerts a force on the body known as the buoyant force. This force acts vertically upward through a point called the center of buoyancy, which is the center of the displaced fluid volume. According to Archimedes' principle, the magnitude of the buoyant force is equal to the weight of the fluid...
2.2K
01:07Cohesion
56.4K
Cohesion is the attraction between molecules of the same type, such as water molecules. Water molecules have an overall neutral charge but are polar molecule. An oxygen atom in one water molecule has a partial negative charge that can bind to a hydrogen atom with a partial positive charge in a second water molecule, forming a hydrogen bond. Each water molecule can form up to four hydrogen bonds with other water molecules. Hydrogen bonds are responsible for water's cohesive nature.
On a...
On a...
56.4K
01:24Van der Waals Interactions
67.7K
Atoms and molecules interact with each other through intermolecular forces. These electrostatic forces arise from attractive or repulsive interactions between particles with permanent, partial, or temporary charges. The intermolecular forces between neutral atoms and molecules are ion–dipole, dipole–dipole, and dispersion forces, collectively known as van der Waals forces.
67.7K
02:35Noncovalent Attractions in Biomolecules
59.3K
Noncovalent attractions are associations within and between molecules that influence the shape and structural stability of complexes. These interactions differ from covalent bonding in that they do not involve sharing of electrons.
Four types of noncovalent interactions are hydrogen bonds, van der Waals forces, ionic bonds, and hydrophobic interactions.
Hydrogen bonding results from the electrostatic attraction of a hydrogen atom covalently bonded to a strong-electronegative atom like oxygen,...
Four types of noncovalent interactions are hydrogen bonds, van der Waals forces, ionic bonds, and hydrophobic interactions.
Hydrogen bonding results from the electrostatic attraction of a hydrogen atom covalently bonded to a strong-electronegative atom like oxygen,...
59.3K
01:04Hydrostatic Pressure Force on a Curved Surface
2.2K
Hydrostatic pressure on curved surfaces is a fundamental concept in fluid mechanics with broad applications in the civil engineering field. When fluid is in contact with a curved surface, as in a reservoir, dam, or storage tank, it exerts pressure that varies in magnitude and direction along the curved surface. To assess the total hydrostatic force exerted by the fluid on a curved structure, engineers typically isolate the fluid volume adjacent to the surface and analyze the forces acting on...
2.2K