ISSN:0031-9171    

DOI:10.1063/1.1724331

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

An attempt is made to analyze the factors which determine the operation of the bubble chamber. It is concluded that the majority of bubbles in conventional chambers are nucleated by moderately energetic free electrons produced by the incident particles in Coulomb encounters. Nuclei are displaced too infrequently by Coulomb encounters to account for the observed densities of bubbles. The electrons deposit their kinetic energy in highly localized regions which then are the source of explosions which produce bubbles of greater than critical size in a time of the order of 10−10or 10−11sec. The bubbles grow subsequently by evaporation of the fluid. The temperature of the fluid should be sufficiently close to the critical temperature that the energy required to produce the bubble of critical size can be provided by an electron with a range comparable to or less than the diameter of the bubble of critical size. Otherwise the electron will be unable to localize its energy in a sufficiently small volume in any but highly improbable cases. It is also concluded that the viscosity of the liquid plays a very important role in determining the threshold energy for forming a bubble of critical size when it has a value near 1 centipoise or larger.

ISSN:0031-9171    

DOI:10.1063/1.1724333

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

In order to study wall effects in shock tube flows, measurements have been made of shock strength, of average density across the tube, and of pressure at the walls. These measurements are compared with explicit predictions of Trimpi and Cohen and of Mirels and Braun. Under conditions where the theories should apply, they predict shock attenuation and values of the flow variables sufficiently well to justify as essentially correct the assumptions that the turbulent boundary layer produced by the shock is similar to the boundary layer observed in steady flows and that waves generated by wall effects can be considered as one‐dimensional. A need for some modification of the theories is indicated, however, by lack of quantitative agreement in certain cases. Considerable mixing of the hot and cold gases is observed to occur. Neither theory attempts to explain the mixing nor takes into account its effects on wave propagation.

ISSN:0031-9171    

DOI:10.1063/1.1724329

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The fundamental conservation equations governing fluid dynamics and including radiation are written down. The Rankine‐Hugoniot conditions are derived for shock waves subjected to radiation flux. Similarity solutions are obtained for the constant density and constant pressure cases. Some results are stated for the combined radiation‐fluid dynamics corresponding to a power law dependence of the temperature on the time.

ISSN:0031-9171    

DOI:10.1063/1.1724332

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

The theory of viscous flow between two rotating coaxial cylinders as developed by Taylor and Chandrasekhar is extended to the case when the fluid is an electrical conductor and a circular magnetic field (i.e., one whose lines of force are concentric with the cylinder walls) is present. The equations governing marginal stability are derived, and boundary conditions for perfectly conducting cylinders (Fermi boundary conditions) are formulated for two cases when the difference in cylinder radii is small compared to their mean. In the first case, co‐rotating cylinders, the underlying characteristic value problem is solved by a variational method developed by Chandrasekhar to show that convective instability rather than oscillatory overstability will occur for realizable magnetic field strengths. In the second case, co‐rotating and counter‐rotating cylinders, the underlying characteristic value problem is solved by an expansion in orthogonal functions method developed by Chandrasekhar to determine critical Taylor numbers for marginal stability. The magnetic field inhibits the onset of instability, but this effect is quite small as the hydromagnetic interaction involves displacement but not distortion of the magnetic lines of force.

ISSN:0031-9171    

DOI:10.1063/1.1724334

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

Under the restrictions of (A) isotropy in turbulent velocity and concentration fluctuation fields, (B) negligible effect of reaction on fluid motion, and (C) negligible effect of heat of reaction on local reaction rate, equations have been deduced for some statistical functions of the concentration of reactant. For a first‐order reaction the simplest equations do not differ in general character from those of pure mixing without reaction, but the nonlinear nature of second‐order reactions introduces decided differences. Solutions for the decay rates of mean concentration and fluctuations have been obtained in some limiting cases and with some simplifying assumptions. The principal hypothesis introduced is that a first‐order reaction has no effect on the size structure of the scalar field.

ISSN:0031-9171    

DOI:10.1063/1.1724335

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A chemically reactive species is emitted from the surface of a body located in a hydrodynamic flow field. It diffuses into the fluid where it undergoes a simple isothermal, homogeneous transformation. The analysis given enables one to trace the reaction history of this component in a laminar boundary layer flow which develops over the surface of a body.For illustration the development of a first‐order reaction in the neighborhood of a flat plate is calculated. Two reaction types are considered. In one case the reactant is destroyed; in the other, it is generated. The reaction histories show a number of interesting features which are discussed in some detail.

ISSN:0031-9171    

DOI:10.1063/1.1724336

出版商:AIP    

年代:1958

数据来源: AIP

摘要:

A systematic generalization of the Mayer cluster integral theory has been developed to deal with the quantum statistics of interacting particles. The grand partition function appears in a natural way and the cluster integrals are integrals over propagators which are derived from the Green's function solution of the Bloch equation (which follows from the Schroedinger equation by replacing it/ℏ by &bgr; = 1/kT). Every cluster integral can be represented by a hybrid of a Mayer graph and a Feynman diagram in (&bgr;,r) space.The generalization of classical ring cluster integrals has been analyzed. It is shown that in the case of the electron gas the classical limit of the contribution of these integrals to the grand partition function yields the Debye‐Huckel theory while the low temperature limit leads to the Gell‐Mann—Brueckner equation for the correlation energy of the ground state.A prescription is given for the construction of the cluster integral associated with any given diagram.

ISSN:0031-9171    

DOI:10.1063/1.1724337

出版商:AIP    

年代:1958

数据来源: AIP