Kutateladze Institute of Thermophysics of the Siberian Branch of the Russian Academy of Sciences (Russian: Институт теплофизики имени С. С. Кутателадзе СО РАН) is a research institute based in Novosibirsk, Russia. It was founded in 1957..
The paper describes the response of a viscoelastic layer glued onto a solid base to a non-stationary convective pressure wave. A complete equation of motion of coating material particles in the case of two-dimensional deformations is derived and it takes into account the viscosity of the medium. A system of equations for calculating the longitudinal and transverse dynamic compliance, determined by the ratio of the displacement components to the applied pressure, is obtained. The derived equations allow the description of not only stationary oscillations of the coating, but also the process of their stabilization. It is noted that, in addition to viscosity and Poisson ratio, stationary and dynamic compliances depend only on two parameters: the ratio of the disturbance wave velocity to the propagation velocity of shear oscillations in the coating and the ratio of the wavelength to the coating thickness. An example of calculating stationary compliance for a typical case of a silicone rubber coating is given. Attention is drawn to the need to take into account the transition period of the forced oscillation stabilization, since the coating cannot oscillate instantly due to inertia and viscosity. Known attempts to calculate this process have been analyzed.
The results of direct numerical simulation (DNS) of the effect of a horizontal surface temperature gradient on the dynamics of a thermal convective flow are presented. A series of simulations was performed at moderate Rayleigh numbers (105–108). The computational domain was rectangular and its two horizontal walls had a specified mean temperature difference, leading to the formation of a free-convective flow. The temperature on the lower wall was nonuniformly distributed along one of the horizontal axes. Convective cells formed due to the vertical density gradient were subjected to a weak horizontal temperature gradient, which led to their deformation and transfer towards the central axis of the computational domain. As a result, intense coherent horizontal oscillations of the position of the central updraft at a low frequency were observed. This frequency depended weakly on the Rayleigh number, while the oscillations amplitude was increasing with the increase in Ra. This low-frequency oscillation effect is not evident in two-dimensional modeling and arises from the interaction of adjacent three-dimensional convective cells entering the central updraft. The authors propose an asymptotic estimate for the period of these fluctuations. It is shown that the fluctuations do not disappear with increasing Rayleigh number, suggesting their influence on heat and mass transfer in natural flows.
It is known that passive heat transfer intensification in tubes is carried out by acting on the flow with inserted intensifiers or by changing the shape of the heat exchange surface. The presented work deals with the study of the intensification process using spherical turbulators located in a horizontal stainless steel channel. Experimental data were obtained on the heat transfer intensity and pressure drop during circulation of an alcohol-water mixture with a concentration of 30
The influence of the mass flow rate ratio of the inlet flows of distilled water on the efficiency of liquid mixing within a T-shaped microchannel was studied using numerical and experimental modeling. The model was verified by comparing the calculated results with experimental data. High-resolution particle image velocimetry was used to measure the flow velocity characteristics. Computer modeling was used to obtain and describe the flow structure and the dynamics of flow pattern changes at unequal mass flow rates. The possibility of increasing the efficiency of liquid mixing by varying the mass flow rate ratio is demonstrated.
This work deals with the study of cavitation in a slit channel when flowing around NACA 0012 hydrofoils with a smooth and periodic-textured surface. The research was aimed at the description of the dynamics of cavitation development on smooth and rough hydrofoils and determination of differences between them. Computer modeling of cavitating flow in a slit channel formed behind an obstacle in the form of a hydrofoil was performed in the modern CFD package STAR-CCM+. Visualization was obtained, computer modeling was carried out in a wide range of parameters and a comparison with experimental data on the cavitating flow was made. The effect of periodic texture on the features of occurrence and development of a cavitation on the hydrofoil is described. The flow structure in cells of hydrofoil textured surface is shown. The obtained results can be used to control effectively the cavitation process in slit channels of various hydraulic engineering devices.
