Investigation of the influence of nonbreaking waves on the turbulence using PIV methods within laboratory modelling of the upper layer ocean dynamics

The influence of nonbreaking waves on the mixing processes in the upper layer of the ocean during wind-wave interaction was investigated under the conditions of laboratory modeling at the Thermostratified Wind Wave Tank (TSWiWaT) of IAP RAS. Experiments of three types were performed. In the first experiment, shear flow in water was induced using a weak wind to avoid the excitation of surface waves. In the second experiment, in the absence of wind, only a long smooth surface wave was generated using an underwater paddle wavemaker. The third type of experiment combined the conditions of the previous two, i.e. at the same time the wave generator was working and the wind was blowing. In all experiments, the underwater flow characteristics were measured using the PIV method. Vertical profiles of the mean velocity and fluctuations for two components were obtained. It was shown that the presence of waves leads to an increase in the average drift current, as well as, more importantly, on the level of fluctuations over the entire depth of the recorded profile by more than 3 times. This was observed for horizontal and vertical turbulent velocity components both.

Nivelul de acumulare al unor microelemente în peștii Cyprinidae, Percidae și Esocidae din fl. Nistru

The paper includes the results of the laboratory modelling of accumulation of selenium in early ontogenesis of carp and of investigation of the accumulation of a range of trace elements in the skeletal muscles, gonads, liver, gills and skin in fish of Cyprinidae, Percidae and Esocidae families from the Dniester River.

An Application of the Visualization Methods for Investigation Small Scale Processes in the Atmosphere-hydrosphere Boundary Layer within Laboratory Experiments on the Wind-wave Facilities

Hydro/aerodynamic laboratory experiment aimed at the laboratory modelling of the physical processes marine atmospheric boundary layer is one of the most complicated. Especial features as spray of droplets, the bubbles in the water and foam generated during the breaking of the waves should be taken into account when modelling extreme weather conditions caused by severe winds. Thus, in the experiment we are dealing with a multiphase turbulent flow with a free boundary. This investigation describes developing approaches to the use of optical methods based on visualization for performing these investigations. Presented results were obtained in experiments carried out on wind-wave facilities. To study the processes of fragmentation of the water surface leading to the formation of droplets and foam, high-speed multi-angle video taking is used in combination with the shadow imaging method.

Properties of toroidal magnetic fields in axial plasma flow on the PF-1000U plasma focus facility

This paper presents the results of studies of plasma flow parameters on the PF-1000U facility. A distinctive feature of this facility is the ability to create profiled initial gas distributions using gas puffs. In the experiments described, a combined system for filling the vacuum chamber with a working gas was used, in which an additional injection of various gases (deuterium, helium, neon and their mixtures) into the axial region of the chamber prefilled with deuterium was performed using a pulse valve. Thus, both the pinching processes and, accordingly, the generation of axial plasma flows and the conditions of their propagation in the background gas of the facility chamber were affected. Regimes with the generation of compact stable plasma formations propagating over long distances were found. The results obtained can be used in laboratory modelling of astrophysical jets from young stellar objects.