CRITICAL SHEAR VISCOSITY EXPONENT: EXPERIMENT AND THEORY

Static and dynamic responses can become singular near the critical point, because of the long ranged fluctuations in the system. In a gas-liquid system near the critical point or a binary liquid near the consolute point, this leads to divergent transport properties at the critical temperature. While the thermal conductivity and bulk viscosity exhibit strong divergence, the shear viscosity exhibits a weak divergence. The divergence of shear viscosity, being characterised by a small exponent, requires careful theoretical and experimental study. Since experiments, carried out in space shuttle, are not plagued by gravity induced stratification, it is possible to approach the critical point closely and thus carry out an accurate determination of the small exponent. The precise measurement demands a careful calculation. In this article, we will try to elaborate on the experimental and theoretical progress done so far on the critical shear viscosity exponent .