Serge Semin | Nizhny Novgorod State Technical University (original) (raw)
Researcher of water waves dynamics with 5 years of experience in the numerical and mathematical modeling of the internal and surface, fully/weakly nonlinear and linear waves in closed and opened water areas, PhD in Physics and Mathematics, Master’s degree in Applied Mathematics and Informatics with comprehensive experience in IT industry as senior software developer
• Extensive experience in numerical modeling of the fully nonlinear/linear internal waves dynamic, surface waves and sediment transport processes
• Expertise in the numerical models of the various complexity: MITgcm, Gerris, ROMS, SWASH, SWAN
• Skilled in numerical models research and development using Matlab/Scilab, Fortran, C/C++
• Extensive knowledge of the multithreaded and distributed software development
• Experience of work as part of the multinational and remotely distributed teams
Phone: +79200318881
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Papers by Serge Semin
The problem of transformation of quasimonochromatic wavetrains of surface gravity waves with narr... more The problem of transformation of quasimonochromatic wavetrains of surface gravity waves with narrow spatial-temporal spectra on the bottom shelf is considered in the linear approximation. By means of numerical modeling, the transmission and reflection coefficients are determined as functions of the depth ratio and wave number (frequency) of an incident wave. The approximation formulae are proposed for the coefficients of wave transformation. The characteristic features of these formulae are analyzed. It is shown that the numerical results agree quite satisfactorily with the proposed approximation formulae.
We analyze in detail the problem of the transformation of surface gravity waves over a bottom ste... more We analyze in detail the problem of the transformation of surface gravity waves over a bottom step in a basin of arbitrary depth in the linear approximation. We found that strict analytical results can be obtained only when a denumerable set of modes condensed near the step is taken into account. At the same time, one can use the formulas suggested in this work for the practical calculations. They provide an accuracy of 5% for the wave transmission coefficient. The specific peculiarities of transformation coefficients are discussed, including their nonmonotonic dependence on the parameters, asymptotic behavior at strong depth variations, etc. The data of a direct numerical simulation of wave transformation over a step are presented, which are compared with the exact and approximate formulas. The coefficients of excitation of modes condensed near the step by an incident quasimonochromatic wave are found. A relationship between the transformation coefficients that follows from the conservation law of wave energy flux is found.
Transformation of internal gravity waves on the oceanic shelf is studied theoretically and numeri... more Transformation of internal gravity waves on the oceanic shelf is studied theoretically and numerically within the framework of the linear approximation. It is assumed that internal waves pass over the continental shelf experiencing partial transmission and reflection. The problem is studied for the simplified model of the shelf represented by the sharp bottom ledge. The fluid stratification is assumed to be a two-layer with the density of the upper layer being r0, and the density of the lower layer being r1. The theoretical approximate formulae are proposed for the transmission and reflection coefficients as the functions of an incoming wave number, density ratio, a depth of the interface between the layers, and depth ratio before and after the ledge edge. Results of direct numerical modelling of linear internal waves transformation are presented as functions of all aforementioned parameters. The modelling was undertaken by means of the numerical code MITgcm. The results obtained are analysed in details and compared against the proposed formulae.
The transformation of small-amplitude internal waves on the oceanic shelf is studied numerically.... more The transformation of small-amplitude internal waves on the oceanic shelf is studied numerically. The transmission and reflection coefficients are found for the simplified step-wise model of the oceanic shelf in a two-layer fluid. The approximate formulae are proposed for the transformation coefficients as functions of incident wavenumber, density ratio of layers, depth of the pycnocline and height of the bottom step. Results of direct numerical modelling of internal wave transformation are obtained and presented as functions of all aforementioned parameters. It is shown that there is a good agreement between the outcomes of approximate theory and numerical data. Both the theoretical and the numerical results agree well with the law of energy flux conservation.
The problem of transformation of quasimonochromatic wavetrains of surface gravity waves with narr... more The problem of transformation of quasimonochromatic wavetrains of surface gravity waves with narrow spatial-temporal spectra on the bottom shelf is considered in the linear approximation. By means of numerical modeling, the transmission and reflection coefficients are determined as functions of the depth ratio and wave number (frequency) of an incident wave. The approximation formulae are proposed for the coefficients of wave transformation. The characteristic features of these formulae are analyzed. It is shown that the numerical results agree quite satisfactorily with the proposed approximation formulae.
We analyze in detail the problem of the transformation of surface gravity waves over a bottom ste... more We analyze in detail the problem of the transformation of surface gravity waves over a bottom step in a basin of arbitrary depth in the linear approximation. We found that strict analytical results can be obtained only when a denumerable set of modes condensed near the step is taken into account. At the same time, one can use the formulas suggested in this work for the practical calculations. They provide an accuracy of 5% for the wave transmission coefficient. The specific peculiarities of transformation coefficients are discussed, including their nonmonotonic dependence on the parameters, asymptotic behavior at strong depth variations, etc. The data of a direct numerical simulation of wave transformation over a step are presented, which are compared with the exact and approximate formulas. The coefficients of excitation of modes condensed near the step by an incident quasimonochromatic wave are found. A relationship between the transformation coefficients that follows from the conservation law of wave energy flux is found.
Transformation of internal gravity waves on the oceanic shelf is studied theoretically and numeri... more Transformation of internal gravity waves on the oceanic shelf is studied theoretically and numerically within the framework of the linear approximation. It is assumed that internal waves pass over the continental shelf experiencing partial transmission and reflection. The problem is studied for the simplified model of the shelf represented by the sharp bottom ledge. The fluid stratification is assumed to be a two-layer with the density of the upper layer being r0, and the density of the lower layer being r1. The theoretical approximate formulae are proposed for the transmission and reflection coefficients as the functions of an incoming wave number, density ratio, a depth of the interface between the layers, and depth ratio before and after the ledge edge. Results of direct numerical modelling of linear internal waves transformation are presented as functions of all aforementioned parameters. The modelling was undertaken by means of the numerical code MITgcm. The results obtained are analysed in details and compared against the proposed formulae.
The transformation of small-amplitude internal waves on the oceanic shelf is studied numerically.... more The transformation of small-amplitude internal waves on the oceanic shelf is studied numerically. The transmission and reflection coefficients are found for the simplified step-wise model of the oceanic shelf in a two-layer fluid. The approximate formulae are proposed for the transformation coefficients as functions of incident wavenumber, density ratio of layers, depth of the pycnocline and height of the bottom step. Results of direct numerical modelling of internal wave transformation are obtained and presented as functions of all aforementioned parameters. It is shown that there is a good agreement between the outcomes of approximate theory and numerical data. Both the theoretical and the numerical results agree well with the law of energy flux conservation.