In this paper we are concerned with a linear problem of hydroelastic instability in a turbulent boundary layer over a compliant coating of a ribbon-like material. A dispersion relation for hydroelastic waves is written in terms of complex stiffness coefficients that characterize the deformation of the compliant surface and the turbulent flow response to the wavy surface flexure. A membrane-type approximation is proposed for the stiffness coefficient of solid coating at sufficiently low frequencies. In order to evaluate the turbulent flow response, the eddy-viscosity model in a curvilinear coordinate system is employed. The quasipotential approximation for the description of flow stiffness is confirmed on the basis of the computations. The critical flow speed and the parameters of the hydroelastic waves at the instability threshold are determined both within general definitions for the stiffness coefficients and for their approximations. The computational results are compared with available experimental observations.
An algorithm is proposed for determining water level in inland water bodies and coastal zones of seas and oceans. The algorithm was tested for the water area of the Gorki Reservoir, for which radioaltimeter databases show considerable data losses. A model was constructed, describing the shape of a mean impulse reflected from a statistically heterogeneous piecewise constant underlying surface (topographic model). The model was used to substantiate criteria for data choice for the Gorki Reservoir and to construct a regional algorithm for estimating water level using data from Jason 1 satellite and based on the analysis of the shape of telemetric impulses (retracking). Water level was calculated with the use of an algorithm of regional adap tive retracking Sensor Geophysical Data Record databases for the Gorki and Rybinsk reservoirs. Algorithm application has been shown to considerably increase the amount of actual data and significantly improve the accuracy of water level evaluation. The general principles of retracking of a complex domain (a coastal zone, an inland water body, etc.) are discussed. The principles are based on the calculation of signal with allowance made for the roughness of the reflecting surface and they can be applied to different geographic regions.
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