Measurement of the Bulk Viscosity of Liquid by Brillouin Scattering (CAT#: STEM-ST-0092-YJL)

Name: Measurement of the Bulk Viscosity of Liquid by Brillouin Scattering
SKU: STEM-ST-0092-YJL
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Introduction

Bulk viscosity is an important parameter used in fluid dynamics. Classically, viscosity was measured via the absorption of supersonic waves; the bulk viscosity was determined from the difference between measured and theoretical values of absorption by the liquid. Recently the approach has been to measure shear viscosity at different temperatures and calculate the bulk viscosity according to the theories relating shear and bulk viscosities. Consequently, there are little data on the bulk viscosity of liquid over a wide range of temperatures.

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Principle Applications Procedure Materials

Principle

From a quantum point of view, Brillouin scattering is an interaction of light photons with acoustic or vibrational quanta (phonons), with magnetic spin waves (magnons), or with other low frequency quasiparticles interacting with light. The interaction consists of an inelastic scattering process in which a phonon or magnon is either created (Stokes process) or annihilated (anti-Stokes process). The energy of the scattered light is slightly changed, that is decreased for a Stokes process and increased for an anti-Stokes process. This shift, known as the Brillouin shift, is equal to the energy of the interacting phonon and magnon and thus Brillouin scattering can be used to measure phonon and magnon energies.