Related Experiment Video
Updated: Jul 4, 2026
09:31
Surface Properties of Synthesized Nanoporous Carbon and Silica Matrices
Published on: March 27, 2019
Theoretical model for the wetting of a rough surface
K M Hay1, M I Dragila, J Liburdy
1Department of Physics, Oregon State University, Corvallis, OR, USA. hayk@onid.orst.edu
Journal of Colloid and Interface Science
|July 1, 2008
Summary
Surface roughness significantly impacts fluid spreading on surfaces, influencing hydrophobic and hydrophilic behaviors. A new model explains fluid invasion into rough surfaces, predicting spreading based on surface geometry and fluid properties.
Area of Science:
- Fluid dynamics
- Surface science
- Geophysics
Background:
- Understanding fluid movement on rough surfaces is crucial for applications like contaminant transport in rock fractures.
- Surface roughness is known to enhance both hydrophobic and hydrophilic fluid behaviors, affecting spreading dynamics.
Purpose of the Study:
- To theoretically investigate the influence of surface roughness on fluid spreading mechanisms.
- To develop a model classifying fluid spreading regimes on rough surfaces.
- To derive an analytical equation for fluid invasion into roughness.
Main Methods:
- A theoretical model was developed, classifying spreading into microscopic, mesoscopic, and macroscopic regimes.
- An analytical equation was derived based on the balance of capillary and frictional forces.
- Viscous dissipation estimation methods were compared against experimental data for fluid rise on roughness.
Main Results:
- The study identified three spreading regimes: microscopic precursor film, mesoscopic invasion, and macroscopic reaction.
- An analytical solution predicts fluid movement with a square root of time dependence, akin to diffusion.
- Accurate accounting for roughness shape, particularly using a hydraulic diameter approximation, best explains experimental data.
Conclusions:
- The developed theory highlights a critical contact angle dependent on roughness geometry, determining spreading or resistance.
- The findings provide a framework for predicting fluid invasion dynamics in unsaturated rough-walled fractures.
- Improved models for viscous dissipation, considering detailed roughness, enhance the accuracy of fluid spreading predictions.
Related Concept Videos
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...
01:09Theories of Dissolution: The Danckwerts' Model and Interfacial Barrier Model
Various dissolution theories provide insight into the factors that influence the dissolution rate. Danckwerts' Model suggests that turbulence, rather than a stagnant layer, characterizes the dissolution medium at the solid-liquid interface. In this model, the agitated solvent contains macroscopic packets that move to the interface via eddy currents, facilitating the absorption and delivery of the drug to the bulk solution. The regular replenishment of solvent packets maintains the concentration...
01:22Surface Tension of Fluid
Surface tension is a fundamental property of fluids, occurring at the boundary between a liquid and a gas or between two immiscible liquids. This phenomenon arises from the cohesive forces between molecules at the fluid's surface, creating an effect similar to a stretched elastic membrane. Inside each fluid, molecules are equally attracted in all directions by neighboring molecules, but surface molecules experience a net inward force, resulting in surface tension.
Surface tension varies with...
Surface tension varies with...
01:16Surface Tension and Surface Energy
When a paint brush is immersed in water, the bristles wave freely inside the water. When it is taken out, the bristles stick together. The reason behind this effect is surface tension.
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
Consider a beaker filled with liquid. The bulk molecules in the liquid experience equal attractive forces on all sides with the surrounding molecules. However, the surface molecules experience a net attractive force downward due to the bulk molecules. The surface of the liquid behaves like a stretched membrane,...
01:13Contact Angle
When a solid is dipped inside a liquid, the liquid surface becomes curved near the contact. For some solid–liquid interfaces, the liquid is pulled up along the solid, while for others, the liquid surface is convex or depressed near the solid surface. This phenomenon can be explained using the concept of cohesive and adhesive forces.
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
The adhesive force is the molecular force between molecules of different materials, that is, between the molecules of the solid and the liquid. The cohesive force...
01:24Surface Tension
Surface tension is defined as the force per unit length (γ) acting along the surface of a liquid. It arises due to strong intermolecular forces of attraction. A molecule located inside the bulk of the liquid is surrounded by other molecules and experiences equal forces in all directions. However, a molecule at the surface experiences unbalanced forces because there are more neighboring molecules below than above. This creates a net inward force that pulls surface molecules toward the interior,...