- Electrohydrodynamic (EHD) effects: When charged surfaces or particles move in a liquid, they create an electric field that induces a flow of ions in the liquid. This flow of ions can generate additional forces on the charged surfaces or particles, known as electrohydrodynamic (EHD) forces. These forces can be attractive or repulsive, depending on the direction of the electric field and the charge of the surfaces or particles.
- Shear-induced migration: When a liquid flows past a charged surface or particle, it can drag the surface charge along with it. This phenomenon is known as shear-induced migration. It can lead to the accumulation of charge at certain locations, which can give rise to additional forces on the charged surfaces or particles.
- Viscoelastic effects: In viscoelastic liquids, the flow of liquid can induce elastic stresses that can affect the forces between charged surfaces or particles. These viscoelastic effects can be particularly important in concentrated suspensions or solutions of polymers.
Flow effects on surfactants in liquids:
- Marangoni effects: Surfactants are molecules that have both hydrophilic (water-loving) and hydrophobic (water-hating) regions. When surfactants are dissolved in a liquid, they tend to accumulate at interfaces between the liquid and air or another immiscible liquid. This accumulation of surfactants can lead to gradients in surface tension, which can generate forces known as Marangoni forces. These forces can drive flows in the liquid and affect the behavior of the surfactants themselves.
- Shear-induced micellization: When a surfactant solution is subjected to shear flow, the shear forces can cause the surfactants to aggregate into micelles. This process is known as shear-induced micellization. The formation of micelles can change the properties of the surfactant solution, such as its viscosity and surface tension.
- Viscoelastic effects: In viscoelastic liquids, the flow of liquid can induce elastic stresses that can affect the behavior of surfactants. These viscoelastic effects can be particularly important in concentrated surfactant solutions or in the presence of polymers.
