液体黏度测定实验的Flash仿真

应用Flash软件设计制作了模拟医用物理实验--奥氏黏度计法测酒精的黏度,对应用仿真方法进行医用物理实验教学进行了尝试,并将仿真结果与在同等条件下进行的真实实验结果做了对比.     

Temperature and density-dependence of shear viscosity in fluids

The shear viscosity is shown to consist of a gas- and a solid-like contribution by using a relaxation theory for fluids. It is evaluated for liquid argon near the triple point, and found to be in good agreement with experiments. The possibility of observing a minimal shear viscosity as in the classical one-component plasma is discussed.     

Power law of shear viscosity in Einstein-Maxwell-Dilaton-Axion model

We construct charged black hole solutions with hyperscaling violation in the infrared(IR) region in Einstein-Maxwell-Dilaton-Axion theory and investigate the temperature behavior of the ratio of holographic shear viscosity to the entropy density. When translational symmetry breaking is relevant in the IR, the power law of the ratio is verified numerically at low temperature T, namely, η/s ～ Tκ, where the values of exponent κ coincide with the analytical results. We also find that the exponent κ is not affected by irrelevant current, but is reduced by the relevant current.     

Sonically produced heat in a fluid with bulk viscosity and shear viscosity

In a viscous fluid, sound produces heat in a spatial pattern which, in general, depends on the relative magnitudes of the shear viscosity coefficient eta and the bulk viscosity coefficient B'. It is well known that when the particle velocity components ui relative to Cartesian coordinates xi are given for an arbitrary sound field, or any field of flow, the volume rate of heat production qv can be determined from a dissipation function in the form B'T1 + eta T2. Here, T1 and T2 are quadratic functions involving derivatives of the type delta ui/delta xj. In this paper, examples are discussed for continuous monofrequency sound fields, including crossed plane waves, as well as focused and unfocused fields. In these examples, spatial distributions of the time-averaged quantity [qv] for media in which the loss mechanism is primarily bulk viscosity are compared to those for media in which shear viscosity dominates.     

Universal behavior of shear viscosity near the freezing point

The dynamics of liquids above the freezing point is studied. It is demonstrated that the available experimental data on shear viscosity of simple liquids can be described in the framework of the so-called weak crystallization theory. The theory predicts that, in the main approximation, shear viscosity is proportional to the (T/T _*−1)^−3/2, where T _* is the temperature close to the freezing temperature. This prediction is in good agreement with experimental data for many substances.     

Universal behavior of shear viscosity near the freezing point

The dynamics of liquids above the freezing point is studied. It is demonstrated that the available experimental data on shear viscosity of simple liquids can be described in the framework of the so-called weak crystallization theory. The theory predicts that, in the main approximation, shear viscosity is proportional to the (T/T _*−1)^−3/2, where T _* is the temperature close to the freezing temperature. This prediction is in good agreement with experimental data for many substances. The text was submitted by the author in English.     

Wave anisotropy of shear viscosity and elasticity

The paper presents the theory of shear wave propagation in a “soft solid” material possessing anisotropy of elastic and dissipative properties. The theory is developed mainly for understanding the nature of the low-frequency acoustic characteristics of skeletal muscles, which carry important diagnostic information on the functional state of muscles and their pathologies. It is shown that the shear elasticity of muscles is determined by two independent moduli. The dissipative properties are determined by the fourth-rank viscosity tensor, which also has two independent components. The propagation velocity and attenuation of shear waves in muscle depend on the relative orientation of three vectors: the wave vector, the polarization vector, and the direction of muscle fiber. For one of the many experiments where attention was distinctly focused on the vector character of the wave process, it was possible to make a comparison with the theory, estimate the elasticity moduli, and obtain agreement with the angular dependence of the wave propagation velocity predicted by the theory.     

Critical scaling of shear viscosity at the jamming transition

We carry out numerical simulations to study transport behavior about the jamming transition of a model granular material in two dimensions at zero temperature. Shear viscosity eta is computed as a function of particle volume density rho and applied shear stress sigma, for diffusively moving particles with a soft core interaction. We find an excellent scaling collapse of our data as a function of the scaling variable sigma/|rho(c)-rho|(Delta), where rho(c) is the critical density at sigma=0 ("point J"), and Delta is the crossover scaling critical exponent. We define a correlation length xi from velocity correlations in the driven steady state and show that it diverges at point J. Our results support the assertion that jamming is a true second-order critical phenomenon.     

Early stage kinetics in a unified model of shear-induced demixing and mechanical shear banding instabilities

We present a unified model of shear-induced demixing and "mechanical" shear banding instabilities in polymeric and surfactant solutions, by combining a simple flow instability with a two-fluid approach to concentration fluctuations. Within this model, we calculate the "spinodal" limit of stability of initially homogeneous shear states to demixing/banding, and predict the selected length and time scales at which inhomogeneity first emerges after a shear start-up "quench" into the unstable region, finding qualitative agreement with experiment. Our analysis is the counterpart, for this driven phase transition, of the Cahn-Hilliard calculation for unsheared fluid-fluid demixing.     

Frequency-dependent shear viscosity, sound velocity, and sound attenuation near the critical point in liquids. III. The shear viscosity

We compare theoretical results for the shear viscosity calculated in one-loop order within the field-theoretical method of the renormalization-group theory with experiments. Our expressions describe the nonasymptotic crossover in both temperature and density, and allow us to consider effects of finite gravitation and finite frequency at which the experiments are performed. In doing so we treat the critical exponent x(eta) of the shear viscosity as an independent parameter, keeping the one-loop value of the Kawasaki amplitude fixed. Within our model we also consider the temperature and density dependence of the thermal diffusion including gravitational effects.     

Suppression of the shear viscosity near the critical temperature in hot QCD

We consider QCD near but above critical temperature T_c. The pressure, susceptibilities and the renormalized Polyakov loop — which is an order parameter for the deconfining phase transition — dramatically change up to temperatures a few times T_c. We refer to this region as a “semi”-QGP, where partial confinement plays important role. We show that the shear viscosity η is suppressed by two powers of the Polyakov loop. This suggests that η/T³ decreases markedly as QCD cools down to temperatures near T_c. We also show a ratio of the viscosity to the entropy becomes small near T_c [Y. Hidaka and R.D. Pisarski, Phase," arXiv:0803.0453 [Phys. Rev. D (to be published)]].     

On the shear viscosity of a strongly coupled one-component plasma

It is shown on the basis of a microscopic theory that the shear viscosity of a one-component plasma exhibits a minimum as a function of temperature.     

The shear viscosity of a trapped Bose-condensed gas

By obtaining Kubo formula type and using nonequilibrium Green’s functions, we calculate the shear viscosity of a trapped Bose-condensed gas below and above the Bose-Einstein condensation temperature (T_BEC). The contributions of the interactions between condensate and noncondensate atoms and between noncondensate atoms take into account to the viscous relaxation time, by evaluating second order self-energies in Beliaev approximation.     

Kinetics calculation on the shear viscosity in hot QEDat finite density

The shear viscosity of QED plasma at finite temperature and density is calculated by solving Boltzmann equation with variational approach. The result shows the small chemical potential enhances the viscosity in leading-log order by adding a chemical potential quadratic term to the viscosity for the pure temperature environment. Arrival of the final proofs: 25 November 2005 PACS: 52.25.Fi, 05.20.Dd, 11.10.Wx     

Lecture notes on shear viscosity in heavy ion collisions

These notes are a summary of a lecture delivered at the 30th Erice School in Nuclear Physics and provide an elementary introduction to shear viscosity as it is applied to heavy ion collisions. After a qualitative review of the ideal and viscous space-time evolutions, I calculate the elliptic flow and discuss how viscosity affects the results.