摘要:

Some aspects of dissipation due to viscosity and heat conduction are investigated for a linear two‐dimensional unbounded stratified flow over obstacles. Under the assumption of hydrostatics and small dissipation, an explicit formula for calculating the flow field in the vicinity of the obstacles is given, which is essentially nondissipative. Far above the obstacles, an asymptotic expression is obtained showing how the disturbance caused by the presence of the obstacles is damped.

ISSN:0031-9171    

DOI:10.1063/1.861290

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A semiclassical model for rotational transition probabilities in dilute gases is used to compute the relaxation of a gas to equilibrium. The governing Boltzmann equation is solved via the direct simulation Monte Carlo method.

ISSN:0031-9171    

DOI:10.1063/1.861291

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

An approximate theoretical solution is presented for the drag force on a small sphere moving through a gas. The result is based on a moment solution to the Boltzmann equation which places no restriction on the Knudsen number. The equation which is obtained for the drag force reduces to the exact solution in the case of both large and small Knudsen number and gives excellent agreement with experimental data.

ISSN:0031-9171    

DOI:10.1063/1.861292

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Numerically ’’exact’’ results for the thermal creep and viscous slip problems for the BGK model and Maxwellian diffuse specular reflection at the wall are obtained by using equations derived earlier by Cercignani, Loyalka, and Cipolla. Results obtained by the use of both the half range and the ’’full‐range’’ expansions are found to be in complete agreement and provide standards of comparison for various approximate methods.

ISSN:0031-9171    

DOI:10.1063/1.861293

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

It follows from an examination of the dispersion relation in the free‐molecule flow limit that the superposition of the different modes can lead to a solution of the boundary value problem of sound propagation in the low density limit. Therefore, a procedure, based on the moment method for solving the full Boltzmann equation, is developed to superimpose the modes found to be present from the dispersion relation. This procedure can be used to determine the boundary value sound distribution function to any order of approximation. Applying this technique to the 13‐moment equations, the boundary value problem of sound propagation in a monatomic gas is solved by superimposing the two modes associated with this approximation.

ISSN:0031-9171    

DOI:10.1063/1.861294

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Molecular‐beam scattering results are analyzed to obtain a consistent and reliable set of potentials for the atom‐molecule interactions N‐N2, N‐O2, O‐N2, O‐O2, N‐NO, and O‐NO, and the molecule‐molecule interactions N2‐N2, N2‐O2, O2‐O2, N2‐NO, O2‐NO, and NO‐NO. These are used to generate a set of transport collision integrals over the range 300–15 000 °K with an estimated uncertainty of about 5%.

ISSN:0031-9171    

DOI:10.1063/1.861295

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Ferromagnetic fluids are a colloidal suspension of subdomain iron particles dispersed in a carrier fluid. Experiments were performed to determine the pressure exerted by the fluid in a uniform and a gradient magnetic field. The pressure measurements were not the same as predicted by the continuum theory. An expression for the pressure jump at the surface of the fluid was proposed for the particular ferromagnetic fluid used based on the experimental measurements. This pressure jump was then used to predict the shape of the surface of the ferrofluid that results when a magnetic field is applied normal to an initially flat ferrofluid surface (ferrofluid spike). An expression for the radius of the shape &rgr; as a function of its distance from the basez, &rgr;=&rgr; (z), was calculated and compared to an enlarged photograph of the particular shape. In the region &rgr;≳0, a simple analytical solution was found. When &rgr; is zero or in the region close to zero, surface tension must be included and a numerical solution was necessary to determine the profile.

ISSN:0031-9171    

DOI:10.1063/1.861296

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The results of anM∞=2 shock wave propagating in air down a shock tube and impinging on a wedge were calculated using both a two‐dimensional Eulerian code and a two‐dimensional Lagrangian code. The air was considered to be an ideal gas with &ggr;=1.4. Both 2:1 and 1:2 wedges were used; these angles are known to generate regular and Mach reflected shock waves, respectively. The calculated results agreed quite well in both shock angle and overpressure with the appropriate theoretical or experimental results. A comparison of the two methods showed that the Eulerian calculation was easier and cheaper, gave equally good shock and expansion wave results, but ’’washed out’’ the slip line whose approximate position was still observable in the Lagrangian calculation.

ISSN:0031-9171    

DOI:10.1063/1.861297

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The structure of a plasma collisional shock wave is examined on the basis of the Navier–Stokes equations and simultaneously on the basis of the Fokker–Planck equation. The resultant structures are compared to check the validity of the Navier–Stokes equations applied to the structures of strong shock waves. The Navier–Stokes equations give quite correct structures for weak shock waves. For the strong shock waves, the detailed structures obtained from the Navier–Stokes equations differ from the results of the Fokker–Planck equation, but the shock thicknesses of the two shock waves are in relatively close agreement.

ISSN:0031-9171    

DOI:10.1063/1.861298

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Laser‐induced motion is calculated for an underdense magnetically confined plasma column subjected to axial laser heating. Perturbation velocities and densities are determined for small values of the disturbance parameter defined as the ratio of the speed of sound to the speed of plasma growth due directly to laser absorption. The calculation confirms that for small values of the disturbance parameter, laser‐induced plasma motion is unimportant. A number of relevant laser heating experiments are examined and classified with respect to induced plasma motions.

ISSN:0031-9171    

DOI:10.1063/1.861299

出版商:AIP    

年代:1975

数据来源: AIP