Magnetostatic relations including fluctuation fields - the local expansion

Using the approach of local expansion, we analyze the magnetostatic relations in the case of conventional turbulence. The turbulent relations are obtained consisten tly for themomentum equation and induction equation of both the average and fluctuation relations.In comparison with the magnetostatic relations as discussed usually, turbulent fluctuationfields produce forces, one of which 1/(4π)(α1×B0)×B0 may have parallel and perpendicular components in the direction of magnetic field, the other of which 1/(4π)K×B0 is introduced by the boundary value of turbulence and is perpendicular to the magnetic field. In the case of 2-dimensional configuration of magnetic field, the basic equation will be reduced into a second-order elliptic equation, which includes some linear and nonlinear terms introduced by turbulent fluctuation fields. Turbulent fields may change the configuration of magnetic field and even shear it non-uniformly. The study on the influence of turbulent fields is significant since they are observed in many astrophysical environments.

Phase relaxation model for 2-phase flows

A phase relaxation model (PRM) for 2-phase flows is presented in this paper on the basis of three principal assumptions. The basic equations for PRM arc derived from the Boltzmann equations for gas-partlcle mixture, The general characteristics and solving process of the PRM's basic equations are also presented and discussed. Many terms in the PRM's basic equations contain a factor ε= ρgρp/ρg+ρp2 which is an intrinsic small parameter for 2-phase mixture, with ρg and ρp being respectively the densities of gas and particle phases.This makes it possible to simplify the computation of the PRM's basic equations. The model is applied to for example, studying file steady propagation of shock waves in gas-particle mixture. The analysis shows that with an increase of shock wave strength the relaxation process behind a gasdynamics shock front becomes a kind of dynamics relaxation instead of the standard exponential relaxation process. A method of determining experimentally the velocity and tem...更多perature relaxation rates (or times) of gas-particle flows is suggested and analyzed.

Evolution and propagation of density waves on galactic disk .1. General evolution equation of wavelet and discussion of its solution

This paper presents a general self-consistent theory of evolution and propagation of wavelets on the galactic disk. A simplified model for this theory, i. e. the thin transition-layer approximation is proposed.There are three types of solutions to the basic equation governing the evolution of wavelets on the disk: (ⅰ) normal propagating type; (ⅱ) swing type; (ⅲ) general evolving type. The results show that the first two types are applicable to a certain domain on the galactic disk and a certain region of the wave number of wavelets. The third is needed to join the other two types and to yield a coherent total picture of the wave motion. From the present theory, it can be seen that the well-known "swing theory" of the G-L sheet model holds only for a certain class of basic states of galaxies.

Effect of current on the evolution of a solitary wave

In this paper, the effect of current on the evolution of a solitary wave is studied. The governing equation in the far field, KdV equation with variable coefficients, is derived. A solitary wave solution is obtained. The fission of a solitary wave is discussed, and the fissible region on the Q～h2-plane and the criterion of the number of the solitary waves after fission are found.

Evolution and propagation of density waves on galactic disk .2. An approximation of the thin transition layer

In this part of the present work, a simplified model—the thin transition layer theory is proposed. The comparison of this model with the G-L sheet model is made.

The magnetohydrostatic equilibrium of horizontal prominence of torus configuration

There are several examples of horizontal ringlike prominences in the observations of Ha monochromatic image of the sun. In the present paper the statie equilibrium of the plasma loop is discussed. The analytic solutions to magnetic field and density are obtained for the axisymmetrie case under the closed boundary condition. Results show the great influence of the gravity and different force-free factors on the configurations of magnetic surfaces and the distributions of thermodynamical quantities for the prominence.

The catastrophic change of steady flow in collapsible tubes

Based on a general background we have developed a mechanical model of the catastrophic change of steady flow in collapsible tubes and got the critical conditions for the catastrophic change analyzing the effects of viscosity, gravity and the longitudinal gradient of external pressure. Several simple flows have been discussed. Furthermore, we conducted three types of model experiments, Results agree with the theoretical critical conditions qualitatively.

Gain saturation in gas flow and chemical lasers

A theoretical model for gain saturation in gas flow and chemical lasers is presented. The theory is applicable to all possible numerical values of τ/τc, where τ is the characteristie flow time for the flowing gas to move across the laser action region and τc is the characteristic collision relaxation time. The saturation effects of the convection and the "source flow" of the inverted population are revealed. A general relation of gain coefficient and some new gain saturation laws are obtained. For the special case of τ/τc1, the present theoretical results agree with the experimental results on the "anomalous" saturation phenomena in the supersonic diffusion HF chemical laser determined recently by Gross and Coffer[8]. The theory also agrees with the measured results of saturation intensity varying with τ/τc in gas flow CO2 lasers[7]. For the special case of τ/τc1, the present theory is consistent with both the standard theory[1] for gas lasers where the gas has no macroscopic motion and the known gain saturation theory[2-5] for gas flow and chemical lasers.

Complete solution of the columbus problem for large-disturbance cases

The Columbus problem has been rigorously solved by Lyapunov's direct approach to the continuous system in gencral cases of large disturbance and the theory has proved to be in strict consistency with Kelvin's experiments.

Naive asymptotic expansion of the water wave generated by a slowly moving body

It is pointed out that the naive asymptotic expansion does not satisfy all the body boundary condition. A nonhomogeneous body boundary condition is obtained from this expansion. It is this condition that the additional wave term must satisfy. Moreover, because of this condition, the wave term must appear. It is pointed out that the zeroth approximation in the naive asymptotic expansion has weak singularity and the singularities become still stronger in the subsequent approximations.

Some comments on the stability theory of mhd shock waves

The stability (evolutionarity) problem for a kind of MHD shock waves is discussed in this paper. That is to solve the interaction problem of MHD shock waves with (2-dimensional) oblique incident disturbances. In other words, the result of gasdynamic shocks is generalized to the case of MHD shocks. The previous conclusion of stability theory of MHD shock waves obtained from the solution of interaction problem of MHD shock wave with (one-dimensional) normal shock wave is that only fast and slow shocks are stable, and intermediate shocks are unstable. However, the results of this paper show that when the small disturbances are the Alfven waves a new stability condition which is related to the parameters in front of and behind the shock wave is derived. When the disturbances are entropy wave and fast and slow magneto acoustic waves the stability condition is related to the frequency of small disturbances. As the limiting ease, i. e. when a normal incident (reflection, refraction) is consid...更多ered, the fast and slow shocks are unstable. The results also show that the conclusion drawn by Kontorovich is invalid for the stability theory of shock waves.

T.E. wave in inhomogeneous magnetized plasma-filled cylindrical waveguide

The T. E. wave in cylindrical wavegulde filled with inhomogeneous plasma immersed in the external uniform longitudinal magnetic field is investigated. The analytic solution expressed in polynomial formed by cutting the confluent hypergeometric function is obtained. Furthermore the eigenfrequency of T. E. wave is obtained.

Short-surface waves radiated by a partially-immersed 3-dimensional oscillating body

The short-surface waves generated by a 3-D arbitrarily oscillating body floating onwater are discussed. In the far-field off the body, the phase and the amplitude functions ofthe radiated waves are determined by the ray method. An undetermined constant is includ-ed in the amplitude function. From the result of Ref. [1], the near-field boundary layersolution near the body waterline is obtained. The amplitude of this solution depends on thewhole wall shape of the body and the slope at the body waterline on the cross-sections per-pendicular to the waterline. By matching the far-field solution with the near-field bound-ary layer solution, the undetermined constant in the amplitude function of the far-fieldradiated waves is determined. For the special case of a half-submerged sphere which per-forms vertical oscillating motion, the result obtained in this paper is in agreement withthat of Ref. [ 2 ].

Magnetic field configurations of radio jets in the double source of radio galaxy

As an improvement of resolution of observations, more and more radio galaxies with radiojets have been identified and many fine structures in the radio jets yielded. In the presentpaper, the two-dimensional magnetohydrodynamical theory is applied to the analysis of themagnetic field configurations in the radio jefs. Two-dimensional results not only are con-sistent theoretically, but also explain the fine structures of observations. One of the theo-retical models is discussed in detail, and is in good agreement as compared with the observedradio jets of NGC6251. The results of the present paper also show that the magneticfields in the radio jets are mainly longitudinal ones and associate with the double sources ofQSOs if the magnetic field of the central object is stronger; the fields in the radio jets aremainly transverse ones and associate with the double sources of radio galaxies if the fieldof the central object is weaker. The magnetic field has great influence on the morphol-ogy and dynamic process.

Steady axi-symmetrical thermocapillary motion of a short melting column

This paper deals with the steady axi-symmetric thermo-capillary motion in a short meltingcolumn.with the assumptions that the Marangoni number M<<1, the Reynolds number Re<<1 andthe capillary number C<<1, at the leading order, the solutions of the problem are obtained inthe form of series. For two kinds of typical cases, symmetric and anti-symmetric distributionof air temperature, the numerical calculations are made. The results describe the effect ofendwalls on thermo-capillary flow.