Related Experiment Video
Updated: May 14, 2026
06:24
High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Dynamic coupling between a multistable defect pattern and flow in nematic liquid crystals confined in a porous medium
1Department of Physics, Kyoto University, Kyoto 606-8502, Japan.
Physical Review Letters
|February 2, 2013
Summary
Nematic liquid crystals in porous media form stable topological defects. Lattice Boltzmann simulations show these defects dynamically couple with flow, enabling flow path recording and nonlinear rheology.
Area of Science:
- Soft Matter Physics
- Fluid Dynamics
- Materials Science
Background:
- Nematic liquid crystals confined in porous media exhibit stable topological defects (disclinations) due to strong anchoring.
- These defect configurations possess significant energy barriers, leading to multistability within the system.
Purpose of the Study:
- To investigate the dynamic coupling between multistable defect patterns and fluid flow in regular porous matrices.
- To explore the influence of flow speed on defect behavior and the resulting rheological properties.
- To determine if flow can control defect patterns and record flow paths.
Main Methods:
- Utilized lattice Boltzmann simulations to model the behavior of liquid crystals in porous media.
- Analyzed the dynamic interactions between topological defects and fluid flow at varying speeds.
- Examined the role of topological constraints within the porous network on defect motion and rheology.
Main Results:
- At low flow speeds, topological defects remain pinned; at higher speeds, they exhibit cyclic motions.
- Observed nonlinear rheological properties dependent on topological constraints.
- Demonstrated that flow can control defect patterns, effectively recording flow paths within the porous channels.
Conclusions:
- Dynamic coupling exists between liquid crystal defect patterns and fluid flow in porous media.
- The multistability of defect patterns allows for the recording of flow history within the porous structure.
- Flow control offers a method to manipulate defect configurations, with implications for microfluidic devices and materials science.
Related Concept Videos
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects
Schottky defects arise when some lattice points in a crystal, such as those in NaCl, remain unoccupied, creating lattice vacancies without disturbing the overall electrical neutrality of the crystal. This defect is common in ionic crystals where the positive and negative ions are similar in size, as seen in sodium chloride and cesium chloride. The presence of Schottky defects enables the crystal to conduct electricity to a small extent through an ionic mechanism. Electric fields cause nearby...
01:34The Fluid Mosaic Model
The fluid mosaic model was first proposed as a visual representation of research observations. The model comprises the composition and dynamics of membranes and serves as a foundation for future membrane-related studies. The model depicts the structure of the plasma membrane with a variety of components, which include phospholipids, proteins, and carbohydrates. These integral molecules are loosely bound, defining the cell’s border and providing fluidity for optimal function.
01:25Imperfections in Crystal Structure: Point, Line and Plane Defects
A perfect crystal, in theory, has a uniform structure with the same unit cell and lattice points throughout. However, any deviation from this periodic arrangement is known as an imperfection or defect. These defects can be categorized into three types: point, line, and plane defects.Point defects occur when there is a deviation from the ideal due to missing atoms, displaced atoms, or additional atoms. These imperfections might occur due to imperfect packing during crystallization or because of...
01:22Couette Flow
Couette flow represents the flow of fluid between two parallel plates, with one plate fixed and the other moving with a constant velocity. This configuration allows for a simplified analysis using the Navier-Stokes equations, which govern fluid motion under conditions of viscosity and incompressibility. For Couette flow, the assumptions include a steady, laminar, incompressible flow with a zero-pressure gradient in the flow direction. This flow type is beneficial for understanding shear-driven...