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This paper presents the results of an experimental study of the turbulent structure of the flow of two parallel jets from long round tubes in the near field of the flow. Measurements were performed for distances between the axes of the tubes s/d = 1.2, 1.8, and 2.4 and for Reynolds numbers Re =5.5x103 and 1.1x104. It is shown that in the near field of the closely spaced twin jets, the longitudinal velocity component on their axis decreases more slowly than in single jets. In this case, the distance between the jets s/d has practically no effect on the transverse scale of the jet and turbulent fluctuations of the longitudinal velocity component. Turbulence anisotropy is practically absent throughout the flow field, except in the outer regions of the jets.

A partially invariant solution of a three-dimensional problem with a free boundary for the Navier-Stokes equations is studied. The flow domain under consideration is a horizontal layer bounded by a solid plane from below and by a flat free surface from above. The vertical velocity and pressure are independent of the x and y coordinates. Three flow modes can be formed for different initial velocities of the flow: stabilization to the quiescent state with time, solution blow up within a finite time, and self-similar regime in which the layer thickness unboundedly increases with time.

Model buoyancy frequency distribution and the Wentzel-Kramers-Brillouin method are used to obtain an asymptotic solution to a problem of constructing solutions that describe internal gravity waves in a stratified medium with a background shear flow slowly varying in depth. Dispersion relation asymptotics are expressed in terms of the Airy functions. Asymptotics for various model distributions of background shear flows are used to obtain analytical representations of dispersion relations and eigenfunctions. Exact and asymptotic results are compared for various distributions of background shear flows and generation regimes typical of a real ocean.

The turbulent mixing on interfaces of three-layer gas systems after shock-wave passage has been studied. The influence of the initial roughness of interfaces on the development of instability and mixing of gases with different density has been investigated. The development of Richtmyer-Meshkov instability has been simulated using the implicit large eddy method and the MIMOZA code. The results of the study have been compared with available experimental data. It has been shown that the width of the mixing region and the enstrophy and mass of mixed gases depend significantly on the degree of interface roughness.

The physical grounds of droplet breakdown in a flow behind a transient shock wave in accordance with one of possible sheet stripping mechanisms (shedding of a liquid boundary layer) are considered. The analysis is performed on the basis of data of high-speed shadowgraphy of the droplet behavior behind the shock wave in the range of the Weber numbers We = 200-2200, measurements of the breakdown induction period, and registration of the ablation character. The condition of instability of the liquid surface by the sheet stripping mechanism and the criterion of interface breakdown are formulated with the use of parameters of an adjoint boundary layer in the fluid. On this basis and with due allowance for previous investigations, a dependence of the delay of droplet breakdown by this mechanism on the fluid characteristics and flow parameters is derived.

Results of optical and gas-dynamic investigations of the microwave discharge plasma under conditions of gas-jet synthesis of diamond are reported. The data are analyzed for determining the temperature and composition of the mixture in the discharge chamber for the purpose of further optimization of the method. The influence of the flow rate of the injected gas mixture on the macroparameters of the gas mixture flow at the exit of the discharge chamber is studied. The temperature and pressure measured in the discharge chamber are used for the numerical analysis of the mixture composition depending on the injected gas flow rate. It is demonstrated that the mixture composition at the exit of the discharge chamber correlates with the rate of diamond synthesis.

Numerical analyses of turbulent boundary layer parameters and skin-friction drag reduction on a flat plate under the effect of air micro-blowing with the use of the SST k-w turbulence model are performed. The macroscale characteristics of a huge number of microjets are simulated by using a microporous wall model (MPWM) incorporated into ANSYS FLUENT by user-defined functions. Numerical results obtained within the Mach number range M=0.2-0.5 (Reynolds number Re=2.88x106-7.20x106) confirm the experimental data of other researchers. Furthermore, a slight increase in the boundary layer thickness, displacement thickness, and momentum thickness, as well as a decrease in the velocity gradient and shear friction are well captured. In comparison to a simple flat plate, applying air micro-blowing reduces the skin-friction coefficient by 51% at the Mach number M=0.4 and blowing fraction of 0.008. Additionally, the skin-friction coefficient decreases as the blowing fraction and Mach number increase.

This paper describes a problem of measuring a gas flow temperature using thermocouples for which the time it takes to reach an equilibrium temperature is shorter than the duration of the measurement process. Results for the numerical simulation of a gas flow in a sensor used to measure a stagnation temperature in short-term wind tunnels are presented. The conjugate problem of a sensor in a supersonic flow is solved and the flow field inside the stagnation chamber is calculated. The temperature of the thermocouple place at the end of the stagnation chamber is determined. The results of simulating the thermocouple readings depend on time and the oncoming flow parameters. The obtained readings of the stagnation temperature sensor are taken as virtual experiment data, which are processed using experimental aerodynamics methods. The “step process” and “two thermocouples” methods are used to restore the stagnation temperature. A difference in thermocouple readings is a normalized thermocouple hardware function. True temperature readings are restored by deconvolution. The restored readings are compared with the initial values of the stagnation temperature in the incoming flow to the sensor. The sources of measurement errors are determined, and the applicability of experimental methods for determining the stagnation temperature in short-term aerodynamic installations, including those with parameters decreasing with time, is substantiated.

The present study elaborates the response of a heat source along with thermomechanical loading in a modified Green-Lindsay generalized thermoelastic half-space with nonlocal and two-temperature parameters. The problem is formulated for the model under consideration by reducing the governing equations into a dimensionless form. The problem is solved by using the Laplace and Fourier transforms. The physical field quantities, such as the stresses, displacement vector components, thermodynamic temperature, and conductive temperature, are found in the domain obtained after the Laplace and Fourier transforms. Numerical inversion techniques are used to recover the equations in the physical domain. Results obtained by using various thermoelasticity theories are compared.

The world experience of applying of medicinal plants shows the prospect for development preparations based on the plant raw materials, including wild ones. In this regard it is necessary the field study for assessment current state of medicinal plants’ populations for rational use and preservation of biological diversity. For the populations of Althaea officinalis , we evaluated the botanical features, ontogenetic spectrum and morphological indicators of plants. So, structural indicators of four populations of А . officinalis in valleys of the rivers Altolkyn, Uter, Sergek and Koneu (Kurmangazysky rayon of Atyrau region) were investigated. It was determined that species composition of communities had 54 species from 50 genera and 26 families. The leading families by number of species were Poaceae , Asteraceae и Fabaceae . The most common species (category I) included 37 taxa; category II included 10 taxa; category III included 4 species; and category IV-V included 2 species. Mesophytes, mesoxerophytes and xeromesophytes dominated among ecological groups; herbaceous perennial, annual and biennial plants dominated among life forms. The maximum morphometric indicators of А . officinalis were noted for populations in the valley of the rive Aktolkyn; the minimum - floodplain of the river Sergek. Analysis of age spectrum made possible to determine, that population in the valet of the river Altolkym was characterized as stable, medium-age; in the floodplain of the river Sergek was stable and young; in the floodplain of the river Uter was non-stable, aging; in the valley of the river Koneu was young. As the results of field investigations, it is possible to recommend implementing action for collection of medicinal raw material of А . officinalis in the populations of the valleys of the rivers Altolkyn, Koneu and Sergek. It is not possible to collect raw material in the valley of the river Uter; actions for reconstruction of its structure are needed.