摘要:

For helium II in uniform rotation, the component of mutual friction along the rotational axisBzhas been studied. The attenuation of second sound transverse to the axis of rotation (characterized by the parameterB) has been compared with the attenuation in the direction of the axis (measured byBz). It is shown: thatB/Bz> 500 over a large range of temperature and frequency; thatBzis not very reproducible; thatBzis dependent on the second sound amplitude; and thatBzis not linear in &OHgr;, the rate of rotation. Within the temperature and frequency range covered by Hall and Vinen the present data onBagree with the results of these authors. Near the &lgr; point,Bincreases rapidly. The anomalous dependence ofBon &OHgr; near 2.0°K as reported by Hall and Vinen is not observed. Some preliminary measurements of the parameterB′ are mentioned.

ISSN:0031-9171    

DOI:10.1063/1.1706810

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The thermodynamic properties of He3and He4solutions in the temperature range 2.2 °K to 2.6 °K have been investigated on the basis of some of the classical theories of nonideal solutions. Calculations have also been made of the excess chemical potentials from the vapor pressure data using some general thermodynamical considerations. These results are then compared with those obtained from the theories considered.

ISSN:0031-9171    

DOI:10.1063/1.1706811

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

Variational principles are developed for the dynamics of a fluid under initial stress in an arbitrary potential field and disturbed from equilibrium. They are formulated in terms of the fluid displacement. Two distinct principles are obtained which are mathematically equivalent but differ fundamentally from the physical viewpoint. The difference results from expressing the potential energy in terms of buoyancy forces or strain energy. A very general stability criterion is obtained. An important new feature is the inclusion of surface integrals in the potential energy. The simplified principle for the case of a liquid is interpreted by means of an analog model. Lagrangian equations and methods of normal coordinates for the evaluation of transient propagation are applicable along with general theorems on the equivalence of group velocity and energy flux. As an illustration the case of a constant gravity field is discussed.

ISSN:0031-9171    

DOI:10.1063/1.1706812

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

General equations for acoustic‐gravity waves in a fluid are derived as a particular case of the theory of elasticity of initially stressed continua. The differential equations for the fluid dynamics and the corresponding variational principles are obtained from the more general results for the elastic solid established earlier by the writer. The transition from solid to fluid is illustrated for the special case of a constant gravity field. The dynamics of a fluid under initial stress is thus brought within the scope of the theory of elasticity providing a unified treatment of wave propagation in composite fluid‐solid systems.

ISSN:0031-9171    

DOI:10.1063/1.1706813

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The continuum, inviscid‐flow equations of gas dynamics are used to predict the effect of thermal radiation on the internal structure of a shock wave. Numerical solutions of the governing equations show that considerable variation in the nature of the temperature and velocity profiles occurs, depending on the magnitude of the over‐all velocity change and the relative strengths of the radiative and convective energy fluxes. A unique feature of the work is the demonstration that, for a range of parametric values, discontinuities necessarily arise in the temperature and velocity profiles. The results include: (a) numerical integration of the basic equations for a representative range of parameters; (b) an analytic study of the equations by means of expansion procedures; (c) a study of the uniqueness of the solutions; (d) proof that previously published investigations cannot be generally applicable since they are restricted to continuous solutions; (e) prediction within a strong shock of a temperature maximum considerably larger than that corresponding to the Rankine‐Hugoniot conditions.

ISSN:0031-9171    

DOI:10.1063/1.1706814

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The case of one‐dimensional magnetogasdynamic flow under the influence of wall friction is investigated. In particular, the case of an infinitely conducting, compressible plasma is studied when the flow direction and the direction of the magnetic field are at right angles to one another. It is shown that all flow variables can be expressed as functions of the ratio of the local flow velocity to the Alfve´n velocity. It is shown that the flow has a variety of regimes delineated by specific singularities and extremities. A typical magnetogasdynamic Fanno flow chart is presented and it is noted that the flow differs markedly from that encountered in classical gasdynamics.

ISSN:0031-9171    

DOI:10.1063/1.1706815

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The finite difference equations utilized to solve the entry problem in laminar magnetohydrodynamic flow are analyzed according to the Lax stability theory to determine the restrictious on velocity and mesh sizes required to permit a stable and convergent system when it is utilized on a computation device.

ISSN:0031-9171    

DOI:10.1063/1.1706816

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The reflection and refraction of plane magnetohydrodynamic waves at an interface separating two different media is studied for various orientations of the external magnetic field. It is pointed out that by making use of trace velocity plots it is a simple matter to determine the nature and disposition of the reflected and refracted waves which are generated by an incident wave of any given species.

ISSN:0031-9171    

DOI:10.1063/1.1706817

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

The effect of an applied electric field on the electrical conductivity of potassium‐seeded acetylene‐air and hydrogen‐oxygen flame plasmas at atmospheric pressure has been explored experimentally. These flames, of interest for magnetohydrodynamic studies, were produced on a Meker‐type burner designed to give a seeded cylindrical core surrounded by an unseeded shield flame. The flow system, unconfined by walls, was particularly advantageous for conductivity measurements. The voltage gradient was determined by means of a floating double probe. The effective flame diameter, seed partial pressure and gas temperature were determined spectroscopically. Good agreement between measured and calculated conductivities was obtained for low current densities. The enhancement of the conductivity observed for increasing current density can be accounted for on the basis of Joule heating of the gas in the case of C2H2/air/K. No simple explanation for the enhancement in the case of H2/O2/K has been found.

ISSN:0031-9171    

DOI:10.1063/1.1706818

出版商:AIP    

年代:1963

数据来源: AIP

摘要:

A factorization theorem is demonstrated for special types of contributions to the time‐dependent collision operatorG00(&tgr;) which plays a central role in the classical master equation derived by I. Prigogine and P. Re´sibois; this theorem expresses the mutual independence of two subgroups of particles when these groups are noninteracting with each other during a given time interval (&tgr;i, &tgr;j) of the collision process. The theorem is applied to rederive in a very direct way the kinetic equation of an homogeneous stable plasma, obtained first by R. Balescu. Other possible applications of the method are also discussed.

ISSN:0031-9171    

DOI:10.1063/1.1706819

出版商:AIP    

年代:1963

数据来源: AIP