摘要:

An exact similarity solution of the Navier–Stokes equations is found. The solution represents the three‐dimensional fluid motion caused by the stretching of a flat boundary.

ISSN:0031-9171    

DOI:10.1063/1.864868

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

A novel experiment is presented on two‐dimensional flows of mercury in a closed domain, in which three‐dimensional perturbations are suppressed by the effect of a uniform magnetic field. An elementary process of an inverse energy cascade is observed, which is approximately described by interaction of two triads in Fourier space. The experimental results are in good agreement with a finite difference numerical method.

ISSN:0031-9171    

DOI:10.1063/1.864869

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

A numerical simulation of large‐scale two‐dimensional turbulence fed in a narrow band of wavenumbers is presented. The development of the inverse energy cascade predicted by Kraichnan [Phys. Fluids10, 1417 (1967)] is observed.

ISSN:0031-9171    

DOI:10.1063/1.864870

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The effect of external noise on the transition of the radial electric field in a nonaxisymmetric torus is studied. Depending on the size of the fluctuations, the transition of the radial electric field can either exhibit hysteresis or choose the path for which the thermodynamic potential (generalized heat production rate)S˙lis an absolute minimum. Fluctuations other than the radial electric field are also studied.

ISSN:0031-9171    

DOI:10.1063/1.864871

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

An approximate scaling law for the linear growth rate of the Rayleigh–Taylor instability of a laser ablatively accelerated fluid slab is given based on two‐dimensional fluid simulations. It is shown that this scaling agrees with one obtained from recent theoretical analyses. This scaling law allows one to substantially reduce the dimensionality of the parameter space.

ISSN:0031-9171    

DOI:10.1063/1.864872

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The mechanism of critical velocity ionization is studied through electrostatic particle simulations which include a neutral‐particle ionization process. It is shown that the rapid ionization of neutral particles takes place when the flow velocity of the neutral particles across a magnetic field exceeds a certain threshold. The mechanism is explained in terms of lower‐hybrid wave excitation by a plasma instability, resultant electron energization, and neutral‐particle ionization. It is found that the phase space relationship between the most unstable wave and the particles remains appropriate for the operation of the above process.

ISSN:0031-9171    

DOI:10.1063/1.864873

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The effect of surface tension on the shape of a two‐dimensional jet emerging from an orifice is considered. It is shown that the slope of the surface profile of the jet is not continuous at the separation points. Both velocity and curvature are infinite at these points. The problem is solved numerically by series truncation. Jet profiles are presented for various values of the surface tension. In addition, perturbation solutions for both small and large values of the surface tension are derived.

ISSN:0031-9171    

DOI:10.1063/1.864874

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The Kelvin–Helmholtz stability of the cylindrical interface between the vapor and liquid phases of a fluid is studied when the vapor is hotter than the liquid and the two phases are enclosed between two cylindrical surfaces coaxial with the interface, and when there is a mass and heat transfer across the interface. Both axisymmetric and asymmetric disturbances are considered. A comparison of the results obtained here with those for the corresponding problem with plane geometry reveals that the plane geometry configuration is more stable than the cylindrical one, and, contrary to the case of Rayleigh–Taylor instability problem, the heat and mass transfer has a destabilizing influence on the system.

ISSN:0031-9171    

DOI:10.1063/1.864849

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The resonant interactions among internal wave trains in a flow consisting of a middle layer of homogeneous fluid in linear shear flow and continguous upper and lower stratified layers of constant velocities are investigated. Three wave trains satisfying the dispersion relations and the so‐called resonant conditions,k1=k2+k3and &sgr;1=&sgr;2+&sgr;3, are considered graphically, and the resonant triads of the same mode are found to exist. Some multiple resonances, i.e., the resonant interactions among waves which are the members of different triads, are also found to happen. The explosive and decay instabilities of multiple resonances are considered qualitatively, and energy exchange is expected to occur among the resonant triads.

ISSN:0031-9171    

DOI:10.1063/1.864875

出版商:AIP    

年代:1984

数据来源: AIP

摘要:

The effect of wind‐tunnel contraction on turbulence intensity is discussed. It is shown that only small eddies decay through contraction in agreement with the classical prediction, whereas large eddies are found to be amplified with an increase in the mean flow velocity. The latter effect becomes appreciable for a flow contraction ratio greater than 4, which is in good agreement with observations.

ISSN:0031-9171    

DOI:10.1063/1.864876

出版商:AIP    

年代:1984

数据来源: AIP