摘要:

The coupling between vibrational relaxation and dissociation in nitrogen is studied. The conservation of vibrational energy equation is derived and the form of the source terms is determined for physically consistent coupling models. Using a computational fluid dynamics method, the results from three current coupling models are compared to existing experimental interferograms for spherical geometries. It is found that the coupling models of Park, Treanor and Marrone, and Macheret and Rich are able to accurately predict the shock standoff distances and reproduce the experimental interference patterns for these conditions. However, there are differences in the vibrational temperature profiles among the coupling models. The experimental interferograms are not sensitive to these differences, though. ©1995 American Institute of Physics.

ISSN:1070-6631    

DOI:10.1063/1.868491

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In a previous paper it was shown that repulsive/attractive forces arise between evaporating/ condensing particles in the free‐molecular regime. Here we obtain explicit expressions for these forces in the case of spherical particles with equal temperatures. The temperature of the surrounding vapor is, generally speaking, different from that of the particles. Numerical results are obtained for different values of the ratios between particle and vapor temperatures and pressures, of the particles radii and of the evaporation coefficients. In the case when the evaporation coefficient equals unity, an exact expression is obtained for the force between particles of different radii. A simple model describing coagulation processes and taking the above‐mentioned forces into account is proposed. It is shown that for large values of the vapor supersaturation, the influence of these forces on the coagulation rate may be very pronounced. ©1995 American Institute of Physics.

ISSN:1070-6631    

DOI:10.1063/1.868492

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Measurements of highly accelerated turbulent boundary layers with and without mean cross‐flow are presented and compared. The accelerated mean longitudinal velocity profiles suggest that the Reynolds shear stress,u’v’, is greater in the two‐dimensional case than in the three‐dimensional case. The measured normal longitudinal Reynolds stress,u’u’, is greater in the three‐dimensional accelerated boundary layer case. The measurements indicate that the Reynolds stress tensor components decouple in the three‐dimensional case; hence, the three‐dimensionality alters the characteristic of nondecoupling observed in highly accelerated two‐dimensional boundary layers. ©1995 American Institute of Physics.

ISSN:1070-6631    

DOI:10.1063/1.868493

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The nonlinear coupling between inertial and Rossby waves is considered accounting for the action of the low‐frequency nonlinear force associated with the inertial waves. It is found that this interaction is governed by a pair of equations, which can be useful for studying the modulational instability of a constant amplitude inertial wave as well as the dynamics of nonlinearly coupled inertial and Rossby waves. ©1995 American Institute of Physics.

ISSN:1070-6631    

DOI:10.1063/1.868494

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The stability of the axisymmetric Burgers vortex solution of the Navier–Stokes equations to two‐dimensional perturbations is studied numerically up to Reynolds numbers,R=&Ggr;/2&pgr;&ngr;, of order 104. No unstable eigenmodes for azimuthal mode numbersn=1,..., 10 are found in this range of Reynolds numbers. Increasing the Reynolds number has a stabilizing effect on the vortex. ©1995 American Institute of Physics.

ISSN:1070-6631    

DOI:10.1063/1.868495

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Recent theoretical results on the behavior of high‐frequency modes in two‐dimensional incompressible turbulent flows are reported. These results show that high‐frequency modes in the dissipation range are slaved to the low‐frequency modes. The physical significance of the results is discussed, as well as its utilization for the numerical simulation of turbulent flows. ©1995 American Institute of Physics.

ISSN:1070-6631    

DOI:10.1063/1.868496

出版商:AIP    

年代:1995

数据来源: AIP