Related Experiment Video
Updated: May 27, 2026
08:45
Glass-Based Devices to Generate Drops and Emulsions
Published on: April 5, 2022
Transient electrohydrodynamics of a liquid drop.
Asghar Esmaeeli1, Payam Sharifi
1Department of Mechanical Engineering and Energy Processes, Southern Illinois University, Carbondale, Illinois 62901, USA. esmaeeli@engr.siu.edu
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|November 9, 2011
Summary
A leaky dielectric liquid drop deforms into an ellipsoid when subjected to a weak electric field. The deformation follows a predictable time-dependent pattern, characterized by a specific time constant.
Area of Science:
- Fluid dynamics
- Electromagnetism
- Materials science
Background:
- Understanding the behavior of liquid drops in electric fields is crucial in various applications.
- Dielectric liquid drops exhibit complex responses to external electrical forces.
Purpose of the Study:
- To investigate the transient deformation of a leaky dielectric liquid drop under a uniform electric field.
- To determine the characteristic time and steady-state deformation of the drop.
- To analyze the contributions of electrical stresses to deformation and fluid flow.
Main Methods:
- Theoretical analysis of a leaky dielectric liquid drop.
- Mathematical modeling of drop deformation under a uniform electric field.
- Derivation of equations for deformation dynamics and characteristic time.
Main Results:
- The drop deforms into an ellipsoid for small distortions from a spherical shape.
- The deformation follows the equation D=D(∞)[1-exp(-t/τ)].
- A formula for the characteristic time (τ) was derived, dependent on drop radius, surface tension, and viscosity ratios.
Conclusions:
- The study provides a quantitative description of the transient deformation of leaky dielectric liquid drops.
- Electrical stresses significantly influence the degree of deformation and internal fluid flow.
- The findings are relevant for microfluidics, electrohydrodynamics, and materials processing.
Related Concept Videos
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...
01:24Electrochemical Systems
Electrochemical systems provide a fascinating insight into the dynamic interplay of charged species within various phases. One notable example is the interaction between a membrane permeable to K⁺ ions but not to Cl⁻ ions, separating an aqueous KCl solution from pure water. As K⁺ ions diffuse through the membrane, they generate net charges on each phase, leading to a potential difference between them.Similarly, when a piece of Zn is immersed in an aqueous ZnSO₄ solution, the Zn metal, composed...
01:30The Electrical Double Layer
In the region where two bulk phases meet, an intricate electric charge distribution arises due to charge transfer, ion adsorption, molecular orientation, and charge distortion. This complex distribution is commonly referred to as the electrical double layer.When a solid electrode interfaces with ions in an electrolyte solution, the speed of electron transfer dictates the rates of oxidation and reduction. The electrode acquires a charge through the escape of atoms into the solution as cations or...
01:29Hydraulic Jump
A hydraulic jump is a sudden rise in fluid depth in open channels, occurring when high-velocity (supercritical) flow transitions to low-velocity (subcritical) flow. This phenomenon requires an upstream Froude number greater than 1, as flows with Fr1<1 remain subcritical, making a hydraulic jump impossible due to the need for negative head loss, which violates thermodynamic principles.The characteristics of a hydraulic jump depend on the upstream Froude number and are classified as...
01:13Excess Pressure Inside a Drop and a Bubble
The shape of a small drop of liquid can be considered spherical, neglecting the effect of gravity. This drop can further be considered as two equal hemispherical drops put together due to surface tension. The forces acting on the spherical drop are due to the pressure of the liquid inside the drop, the pressure due to air outside the drop, and the force due to the surface tension acting on the two hemispherical drops.
01:17Steady, Laminar Flow Between Parallel Plates
Understanding steady, laminar flow between parallel plates is essential for analyzing and designing flow in narrow rectangular channels, commonly found in various water conveyance and drainage systems. The Navier-Stokes equations govern fluid motion and are generally challenging to solve due to their nonlinearity. However, simplifications are possible in certain cases, like the steady laminar flow between parallel plates. For this scenario, we assume steady, incompressible, laminar flow.