Rheotropism of the dowser texture

Area of Science:

• Liquid Crystal Physics
• Soft Matter Science
• Fluid Dynamics

Background:

• Nematic liquid crystals confined between surfaces with homeotropic anchoring can form a pseudo-planar texture, known as the dowser texture.
• This texture is metastable yet can be preserved under specific conditions.
• The dowser texture has been previously shown to be cuneitropic, aligning with thickness gradients.

Purpose of the Study:

• To investigate the rheotropic behavior of the dowser texture.
• To demonstrate the tendency of the dowser texture to align with Poiseuille flows.
• To explore the potential applications of this rheotropic behavior in generating and annihilating nematic monopoles.

Main Methods:

• Observation of the dowser texture's deformation under a slowly alternating linear Poiseuille flow.
• Study of rheotropic effects using elliptical flow patterns generated by modulating the gap thickness between a rigid lens and a flexible glass slide.

Main Results:

• The dowser texture exhibits weathercock behavior, aligning with the direction of Poiseuille flows.
• Deformation of a wound-up dowser texture was observed when subjected to linear Poiseuille flow.
• Elliptical flows were shown to effectively wind the dowser texture.

Conclusions:

• The dowser texture is rheotropic, demonstrating a tendency to follow Poiseuille flows.
• The observed rheotropic behavior, particularly the winding of the texture by elliptical flows, can be utilized in the study of nematic monopole generation and annihilation.