Critical dynamics of an isothermal compressible nonideal fluid.
A pure fluid at its critical point shows a dramatic slow-down in its dynamics, due to a divergence of the order-parameter susceptibility and the coefficient of heat transport. Under isothermal conditions, however, sound waves provide the only possible relaxation mechanism for order-parameter fluctuations. Here we study the critical dynamics of an isothermal, compressible nonideal fluid via scaling arguments and computer simulations of the corresponding fluctuating hydrodynamics equations. We show that, below a critical dimension of 4, the order-parameter dynamics of an isothermal fluid effectively reduces to "model A," characterized by overdamped sound waves and a divergent bulk viscosity. In contrast, the shear viscosity remains finite above two dimensions. Possible applications of the model are discussed.
Interdisciplinary Centre for Advanced Materials Simulation, Ruhr-Universität Bochum, Universitätsstr 90a, 44789 Bochum, Germany. markus.gross@rub.de
Markus
M
Gross
Fathollah
F
Varnik
D016880:Anisotropy; D001703:Biophysics / Q000379:methods*; D002462:Cell Membrane / Q000378:metabolism; D003198:Computer Simulation; D005583:Fourier Analysis; D057446:Hydrodynamics; D015233:Models, Statistical; D008962:Models, Theoretical; D011312:Pressure; D013696:Temperature; D013816:Thermodynamics; D014783:Viscosity