Rarefaction effects in thermally-driven microflows

Rarefied gas flow in a parallel-plate micro-channel is considered, where a streamwise constant temperature gradient is applied in the channel walls. An analytical approach to the problem is conducted based on linearized and semi-linearized forms of the regularized 13-moment equations (R13 equations), which are a set of macroscopic transport equations for rarefied gases at the super-Burnett order. Typical nonequilibrium effects at the boundary, i.e., velocity slip, temperature jump, and formation of Knudsen boundary layers are investigated. Nonlinear contributions lead to temperature, density, and normal stress profiles across the channel which are not reported elsewhere in literature.     

Stationary ‘V’ States for Preferred Motions of Many Particles

We use the discrete kinetic theory with the free-orientation parameter being fixed () to derive the macroscopic velocity field for many particles flowing through a microdomain. Our results resemble qualitatively other hydrodynamical solutions. The V-shaped velocity field changes as the dominant physical parameter (Knudsen number) varies. We also briefly discuss the possible mechanism due to the entropy production along the boundaries.The only author's address after 2007-Aug. is: P.O. Box 30-15, Shanghai 200030, PR China     

Global existence of smooth solutions to two-dimensional compressible isentropic Euler equations for Chaplygin gases

In this paper we investigate the two-dimensional compressible isentropic Euler equations for Chaplygin gases. Under the assumption that the initial data is close to a constant state and the vorticity of the initial velocity vanishes, we prove the global existence of the smooth solution to the Cauchy problem for twodimensional flow of Chaplygin gases.     

Global Existence and Asymptotic Behavior of Solutions to a Free Boundary Problem for the 1D Viscous Radiative and Reactive Gas

In this paper, we study a free boundary problem for the 1D viscous radiative and reactive gas. We prove that for any large initial data, the problem admits a unique global generalized solution. Meanwhile, we obtain the time-asymptotic behavior of the global solutions. Our results improve and generalize the previous work.     

Goldstone Boson Normal Coordinates in Interacting Bose Gases

Spontaneous symmetry breaking (SSB) is one of the basic aspects of collective phenomena such as phase transitions in statistical mechanics or ground-state excitations in field theory. In general, spectral analysis of SSB is related to the presence of a Goldstone boson particle. The explicit construction of the canonical variables (boson field operator and its adjoint) of this boson has so far been an open problem. In this paper, we consider the SSB of Bose–Einstein condensation in two models: the so-called imperfect or mean field Bose gas (which is nothing but a perfect ideal Bose gas including the property of equivalence of ensembles), and the Bogoliubov weakly interacting Bose gas. For both we construct explicitly the Goldstone boson field variables. The remarkable result is that in both cases the field and its adjoint field are formed as the fluctuation operators respectively of the order parameter operator and of the generator of the broken symmetry. The notion of fluctuation operator is essential for our mathematical construction. We find that although the order parameter has a critical fluctuation, the generator of the broken symmetry has a squeezed fluctuation of the same inverse rate. Furthermore, we prove that this canonical pair of variables decouples from the other variables of the system, and that these fluctuations behave dynamically as long-wavelength sound waves or as oscillator variables.     

Anisotropic Lattice Gases

We have studied lattice gases with a particle-conserving dynamic rule that involves two principal parameters. One of them has two limiting values that correspond, respectively, to a large, saturating constant field, which induces a positive particle current, and to a random field (zero net current). Varying the other parameter, either particle attractions or repulsions perpendicular to the field are simulated. The nature of ordering is shown to be independent of the value for the field parameter. In particular, the two indicated limiting cases of the latter lead to the same order-parameter critical behavior, consistent with 1/3, in the presence of a linear interface for attractions in two dimensions. Some qualitative features of the time relaxation are briefly described.     

Identification of phenyl-substituted polycyclic aromatic compounds in ring furnace gases using GC-MS and GC-AED

Summary The ring furnace baking process is an intermediate step in the production of graphite electrodes. In this process coal tar pitch is pyrolized to form amorphous carbon and volatile aromatic and polycyclic aromatic compounds (PACs). These gaseous ring furnace emissions were analysed by GC-MS and GC-AED. As a result of the pyrolytic reactions taking place, several phenyl-substituted PACs are generated, which were identified by their chromatographic retention indices and mass spectra. Pure reference compounds were analysed for verification if available. A number of phenyl-PACs are reported to be present in coal tar-related material, including phenylpyridines and phenyldibenzofurans previously unreported. A formation scheme for phenyl-dibenzofurans on the basis of a radical mechanism is proposed. Dedicated to Prof. Dr. Wolfgang Meyer zu Reckendorf, Münster, on the occasion of his 65th birthday. Presented at the 21^st ISC held in Stuttgart, Germany, 15^th–20^th September, 1996