This review discusses the physical properties of nematic, cholesteric, and smectic liquid crystals. Molecular theories of the liquid crystal phases are discussed and the molecular field theories of the phase transitions between the various liquid crystal phases are presented. The elastic theory and hydrodynamics of liquid crystals is developed. A wide variety of phenomena in liquid crystals, including elastic distortions, disclinations, flow properties, fluctuations, light scattering, wave propagation, nuclear magnetic resonance, effects of magnetic and electric fields, electrohydrodynamics, and optical properties, is discussed.

Physics of liquid crystals

Publisher Summary This chapter discusses the fluid dynamics and science of magnetic liquids. Fluid media composed of solid magnetic particles of subdomain size colloidally dispersed in a liquid carrier are the basis for the highly stable, strongly magnetizable liquids known as magnetic fluids or ferrofluids. The number density of particles in suspension is in the order of lO23/m3. It is the existence of these synthetic materials that makes the study of magnetic liquid fluid dynamics (ferrohydrodynamics) possible. There are two broad ways to make a magnetic fluid: size reduction of coarse material and chemical precipitation of small particles. Size reduction has been done by spark evaporation–condensation, electrolysis, and grinding. Chemical routes include decomposition of metal carbonyls and precipitation from salt solutions. The fluid dynamics of magnetic fluids differ from that of ordinary fluids in that stresses of magnetic origin appear and, unlike in magnetohydrodynamics, there need not be electrical currents. Magnetic fluid pushes the nonmagnetic fluid in the presence of tangential applied field. The fluid motion is normal to the interfacial boundary between the two fluids.

Fluid Dynamics and Science of Magnetic Liquids

Magnetic fluid motion in rotating field

Fluids containing colloidal dispersions of magnetic particles exhibit new phenomena, including a reduction in viscosity under some conditions. In his Perspective, Rosensweig reviews the theoretical and experimental state of magnetic fluid studies.

“Negative Viscosity” in a Magnetic Fluid

Antisymmetric stresses induced by the rigid-body rotation of dipolar suspensions: Vortex flows

Using a simple continuum model for a paramagnetic fluid we analyze a simple shearing flow and parallel flow through a pipe. We also examine the possibility of maintaining a steady circular flow in a circular cylinder by rotating a homogeneous magnetic field.

https://hal.archives-ouvertes.fr/jpa-00207192/document

J.T. Jenkins

Papers

Some simple flows of a para-magnetic fluid