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The evolution properties of free convective motion of air in a heated space have been investigated by numerical modeling. The air motion is always nonstationary and turbulent. The existing technical constraint on the grid scale makes it possible to observe only large-scale eddies. In actual practice, eddies have different dimensions and are always in motion near the midposition; they can disappear and appear again. The larger the eddy size, the smaller the amplitude of fluctuations of the air temperature and velocity in them. The most intense motion is near the window and the heating appliance. At low outdoor temperatures, it is highly likely that a flow of cold air moving over the lower part of the space will appear from the window. [ABSTRACT FROM AUTHOR]

Numerical simulation was carried out in three-dimensional and axisymmetric formulations for the hydrodynamics and mixing of bottom- and tangentially blown air with different temperatures in a cyclone chamber with local supply of tangentially blown air. To calculate vortex flows in the chamber, use was made of the most popular turbulence models k-ε, k-ω, and SA. It has been established that the best correspondence between the results of calculation and experimental data on hydrodynamic parameters (velocity and pressure) and air mixing under nonisothermal conditions is furnished by the k-ε and k-ω models of turbulence. Good agreement of the results of numerical simulation of vortex flows in the indicated chamber in three-dimensional and axisymmetric formulations has been obtained. [ABSTRACT FROM AUTHOR]

The results of the first measurements in Russia of the vortex wakes left by different types of airplanes with the aid of 1.5-μm range home-made commercially manufactured coherent Doppler lidars are presented. The characteristic features of the measurement of vortex wakes by such lidars are considered. The dynamics of the vortex wake left by a Boeing 737-800 is shown. [ABSTRACT FROM AUTHOR]

Different variants of ventilation of the cab of a truck were investigated by numerical simulation methods. An unsteady viscous gas flow was numerically simulated using the VP2/3 package. In the process of numerical simulation of this flow, the Reynolds equations closed with the use of the differential k- ω model of turbulence in the SST modification of Menter were solved numerically. On the basis of analysis of the fields of the velocity, pressure, and turbulence characteristics of the air flows in the truck cab, obtained as a result of their numerical simulation, the efficiency of ventilation of this cab was estimated. [ABSTRACT FROM AUTHOR]

A numerical investigation of the influence of the opening angle of a circular cavity in an U-shaped channel and the Reynolds number of a fluid fl ow in this channel on the local characteristics and turbulence of this fl ow has been performed based on the solution of the Reynolds equations, closed by the old and new Menter shear-stress transfer models and two variants of this model accounting for the curvature of streamlines, with the use of multiblock computational technologies realized in the VP2/3 package. The results of calculations were compared with each other and with experimental data of I. Castro and R. Savelsberg. This comparison has shown that the best agreement between the numerical predictions and experiments is obtained in the case where calculations are performed within the framework of the Leshtsiner-Rody-Isaev approach with correction for the eddy viscosity of the fluid fl ow. It was established that with increase in the Reynolds number and in the opening angle of the cavity the circulation flow in the near-wall layer of the vortex trapped in the cavity intensifies at a practically constant vorticity in the core of the vortex. [ABSTRACT FROM AUTHOR]

Comparative analysis of the results of solution of the steady-state Reynolds equations closed with the use of the shear-stress transfer model for the air fl ow in a divergent channel with suction of the air from the surface of the cylindrical central body positioned in the circular vortex cavity built in the lower wall of the channel with the corresponding experimental data has been performed. [ABSTRACT FROM AUTHOR]

The action of a turbulent air flow on injected normally vertical elevated low-head axisymmetric jets has been investigated experimentally. Empirical formulas have been obtained for the geometry of the axes of isothermal and slightly nonisothermal jets and for dimensionless velocities and temperatures in their cross sections. It has been shown that the above jets are of a higher ejection ability in the transverse flow than submerged jets and wakes. [ABSTRACT FROM AUTHOR]

Parameters of the vortex air flow in an isothermal model of the cyclone chamber are studied. The effect of the air velocity in nozzles on the values and character of the distribution of pressure and tangential and longitudinal velocities of air in the chamber is determined. Numerical modeling of the flow is performed, and it is shown that numerical calculation by the k-w turbulence model is in agreement with experimental data. [ABSTRACT FROM AUTHOR]

The stationary problem on formation of a vapor cloud as a result of evaporation above a liquefied-gas spillage under the action of the wind has been considered. It has been shown that the cloud parameters are influenced by the wind velocity, the degree of turbulence of the incident flow, and the geometric dimensions of the spillage. The results of numerical two-dimensional and three-dimensional calculations of the equation of convective diffusion with allowance for the wind-velocity profile have been presented. The effect of the Knudsen layer above the evaporating liquid on the cloud formation is discussed. [ABSTRACT FROM AUTHOR]

Based on the anisotropic-turbulence model, the velocity profile and the temperature distribution in the flow in the case of steady-state air flow in a circular pipe have been obtained. [ABSTRACT FROM AUTHOR]

The action of a turbulent flow on an injected normally low-head axisymmetric jet has been investigated experimentally. Empirical dependences describing the geometry of the jet axis in a transverse air flow have been obtained. It has been shown that the maximum temperature and velocity curves do not coincide; the thermal axis lies lower than the dynamic axis. The expressions obtained describe a change in the axial values of the velocity and the temperature in the direction of propagation of the jet. It has been shown that the attenuation of dimensionless axial parameters in the jet carried away by the transverse flow is more rapid than that in the case of a submerged jet and a wake. [ABSTRACT FROM AUTHOR]