摘要:

Calculations are carried out to describe the propagation of an acoustic wave which absorbs energy from an external radiation flux applied instantaneously at the gas boundary. This external radiation is considered to be far out of equilibrium with the gas; therefore, emission of radiation by the gas may be neglected. Two analyses are carried out: (1) a perturbation calculation with the radiation affecting the acoustic wave only through second‐order terms, i.e., radiation only slightly perturbs the acoustic wave; (2) an analysis for the transparent limit with the radiation producing a first‐order interaction with the acoustic wave, i.e., the acoustic wave is appreciably changed.

ISSN:0031-9171    

DOI:10.1063/1.1692176

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Equations for the trajectory and overpressure of the shock front of the intermediate strength blast wave(10 < &Dgr;p/p0⪝ 0.02)are developed for spherical, cylindrical, and plane blasts. These equations are based on the correct limit method that provided the trajectory of the blast wave from the inverse pinch to velocities below Mach number 1.16(&Dgr;p/p0 = 0.4). The correct limit equations are an extension of the strong shock similarity solution of G. I. Taylor for the spherical blast and A. Sakurai and S. C. Lin for the cylindrical case. It is now possible, given the energy and ambient gas conditions, to trace the shock front trajectory and overpressure from the very strong through the very weak regimes. Conversely, the shock wave energy can be found from measurement of overpressure or arrival time. Comparisons with experimental data as well as the calculations of H. L. Brode verify the validity of the correct limit equations.

ISSN:0031-9171    

DOI:10.1063/1.1692177

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The linearized problem of heat flow to a cooled plate embedded in a gas is considered and a variational principle for the temperature slip coefficient is given. This variational principle is then applied to a number of special cases analogous to those considered in an earlier paper on momentum slip coefficient. It is found that the temperature slip coefficient is only slightly model‐dependent so that heat‐flow calculations with simple models are not likely to be very incorrect.

ISSN:0031-9171    

DOI:10.1063/1.1692178

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The asymptotic behavior at small Knudsen number for two problems involving the flow of rarefied gas through a circular pipe, Poiseuille flow and thermal creep is treated using the Boltzmann‐Krook equation. By a matching procedure the outer solution for the continuum regime and the solution for the Knudsen layer are determined simultaneously. Actual calculations have been carried out up to second order. A short discussion on second‐order slip condition is also given.

ISSN:0031-9171    

DOI:10.1063/1.1692179

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

An electron‐beam x‐ray technique was used to obtain precise measurements of the density along the stagnation streamline of spherical models tested in aM = 4.2(nominal Mach number) nitrogen stream and aM = 3.8argon stream. Variation of the total pressure and the model radius provided a Re range (based on free‐stream properties and model radius) of 30‐500 in nitrogen, 100‐2000 in argon. The measurements were made with model surface temperatures of 300° K (equal to the total temperature of the flow) and 78° K.

ISSN:0031-9171    

DOI:10.1063/1.1692180

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

To obtain criteria for the validity of the constant coefficient electron diffusion equation, the problem of the positive column is treated using the Boltzmann equation for the electrons. The problem is solved completely for the case of a constant electron‐neutral recoil collision time for momentum transfer, in the limit where inelastic collisions play a weak role in determining the shape of the body of the electron distribution function. Here the bulk of electrons is confined by a space charge potential well, and except for a thin boundary layer near the wall, the electron density assumes a Boltzmann distribution, and the electron temperature and diffusion coefficient are constant. For a general collision frequency it is established that, unless the electron energy relaxation length is small compared with the macroscopic length scale, these results are correct only if the following conditions exist: the recoil collision time is reasonably constant over the domain which makes the major contribution to the velocity space moments of the electron distribution function, and the electron fluxes in configuration and velocity spaces are appropriately small.

ISSN:0031-9171    

DOI:10.1063/1.1692182

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

The stability of the interface between a highly conducting liquid and a flowing, nonconducting gas is studied, supposing a magnetic field to be parallel to the interface. Arbitrary angles are allowed between magnetic field, flow direction and wave vector.

ISSN:0031-9171    

DOI:10.1063/1.1692183

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A study of the stability of a self‐gravitating fluid of variable density with finite resistivity is described. A variational technique is established, and it is proved that the system cannot be overstable. It is also shown that the system is unstable for all wavenumbers and finite resistivity.

ISSN:0031-9171    

DOI:10.1063/1.1692184

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

When the solar wind interacts with the moon, the plasma shadow region on the dark side of the moon forms a long lunar wake. In the plasma umbra a detectable plasma flow is absent and in the penumbra the plasma flux increases from the void condition in the umbra to the interplanetary condition outside. A theoretical model for perturbations of the magnetic field in the plasma shadow is studied by directly solving Maxwell's equations for steady‐state solutions. The perturbation of the field is assumed to be due to the magnetization current, the gradient drift current, and the curvature drift current. Numerical solutions are obtained to describe the variations of the magnetic field, and the results are in good agreement with experimental observations from the Explorer 35 satellite.

ISSN:0031-9171    

DOI:10.1063/1.1692185

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

Equations are set up to describe the quasilinear behavior of a collisionless, relativistic plasma immersed in a uniform, homogeneous magnetic field. Use of the adiabatic assumption, together with an approximation to resonant denominators, enables an estimate to be given of the change of the distribution function due to the turbulent waves. In the particular cases of pure electrostatic waves, magneto‐sonic waves, and cyclotron waves, estimates are made of the rate of energy change of resonant particles. It is shown that some modes exhibit resonant diffusion only when relativistic particles are present and for which there is no nonrelativistic counterpart. It is believed that this calculation may be of some interest in situations where relativistic particles play, or are suspected of playing, a major role; for example, the galactic cosmic ray gas and nonthermal radio sources.

ISSN:0031-9171    

DOI:10.1063/1.1692186

出版商:AIP    

年代:1968

数据来源: AIP