No abstract

Abstract.Results of flood modelling for three cities located in different parts of Russia: (1) Veliky Ustyug at the Northern Dvina river (Europe); (2) Mezhdurechensk at the Tom river (Siberia); and (3) Blagoveschensk at the Amur river (Far East) are presented. The two-dimensional hydrodynamic model of flow in channels and on floodplain STREAM_2D on the basis of the numerical solution of two-dimensional Saint-Venant equations on a hybrid curvilinear quadrangular and rectangular mesh was used for the simulations. Verification of the model through a comparison of simulated inundated areas with outlines of flooded zones from satellite images for known hydrologic situations demonstrate close correspondence (relative errors of 7-12 % in terms of the area for peaks of the analysed floods). Analyses of embankment influence of large-scale levees on the water flow demonstrate that, in some cases, water levels could rise by more than 1 m and the patterns of the flooding zones could significantly differ.

No abstract

The spatial structure of radiation of a surface sliding discharge with a duration of ~ 300 ns (plasma sheet) in inhomogeneous supersonic air flows including oblique shock wave in a discharge chamber of shock tube was experimentally investigated. The flows were created behind plane shock waves with Mach numbers 2.8-4.2; flow Mach numbers were 1.30-1.60. The flow in the discharge chamber included an oblique shock wave generated by the interaction of a supersonic flow with a small obstacle, and then reflected from the upper wall of the discharge chamber. In this case, the shock wave interacted with the boundary layer of the supersonic flow, which formed on the streamlined wall. A surface sliding discharge with a length of 100 mm and 30 mm wide was initiated on a streamlined surface at a certain moment in time. The discharge current, emission spectra, and spatial characteristics of the radiation under various conditions of discharge initiation were obtained and analyzed in experiments. The time dependence of geometry of the discharge glow region was obtained by digital processing of discharge images in flows. CFD simulation was performed to determine the shock-wave structure of the flow in the channel with an obstacle under experimental conditions. The comparison of experimental data with the results of numerical calculation of the supersonic flow field was done. It was shown that the spatial distribution of radiation from a surface sliding discharge visualizes the low density areas and the separation zone formed under the interaction of an oblique shock wave with a boundary layer.