Wyniki wyszukiwania - Biblioteka Nauki

1

Two-dimensional modelling of wave motion in shallow-water areas

100%

Kapiński J.

Archives of Hydro-Engineering and Environmental Mechanics

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2004

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tom Vol. 51, nr 1

3-24

EN

A new mathematical model for prediction of a two-dimensional wave motion in shallow water is presented herein. It can be applied to investigate shoaling, diffraction, refraction, breaking, bottom friction and wave run-up on a beach, as well as mass transport and orbital motion. The model also includes an oblique wave approach to the shore and irregular bottom topography. Such engineering constructions as seawalls, breakwaters and groins are simulated numerically. Simple results of computations, shown in graphic form, indicate possible practical applications of the model.

2

Ecological modeling and Lagrangian approach

86%

Arkhipov B. , Solbakov V. , Solov’ev M. , Shapochkin D.

Open Mathematics

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2013

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tom 11

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nr 4

734-745

EN

A mathematical model is proposed for a quantitative estimation of the damage to biological resources resulting from a pollutant discharge into an aqueous environment. On the basis of the Lagrangian description of fluid motion a set of hydrophysical parameters is introduced with help of which hydrobiologists can estimate the damage. The computation of parameters introduced is illustrated by the example of a model problem of a pollutant spreading in a canal. For the discretization of the problem a deformable Lagrangian grid is used. A special grid reconstruction procedure with the subsequent interpolation of the parameters computed is proposed, which ensures computational stability and preserves the values of the most important hydrophysical parameters. Numerical results are presented.

3

3D Lagrangian modelling of saltating particles diffusion in turbulent water flow

86%

Bialik R. , Nikora V. , Rowiński P.

Acta Geophysica

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2012

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tom Vol. 60, no. 6

1639-1660

EN

A 3D Lagrangian model of the saltation of solid spherical particles on the bed of an open channel flow, accounting for turbulence-induced mechanisms, is proposed and employed as the key tool of the study. The differences between conventional 2D models and a proposed 3D saltation model are discussed and the advantages of the 3D model are highlighted. Particularly, the 3D model includes a special procedure allowing generation of 3D flow velocity fields. This procedure is based on the assumption that the spectra of streamwise, vertical and transverse velocity components are known at any distance from the bed. The 3D model was used to identify and quantify effects of turbulence on particle entrainment and saltation. The analysis of particle trajectories focused on their diffusive nature, clarifying: (i) the effect of particle mobility parameter; (ii) the effect of bed topography; and (iii) the effect of turbulence. Specifically, the results of numerical simulations describing the abovementioned effects on the change in time of the variance are presented. In addition, the change in time of the skewness and kurtosis, which are likely to reflect the turbulence influence on the spread of particles, are also shown. Two different diffusion regimes (local and intermediate) for each of the investigated flow conditions are confidently identified.

4

Seismic analysis of Fractured Koyna Concrete Gravity Dam

86%

Ouzandja D. , Messaad M. , Berrabah A. T. , Belharizi M.

Archives of Hydro-Engineering and Environmental Mechanics

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2023

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tom Vol. 70, nr 1

29--47

EN

Seismic analysis of a fractured dam is a generally complex problem. This paper presents an earthquake behavior investigation of a fractured concrete gravity dam considering dam-reservoir-foundation rock interaction. The Koyna dam profile, located in India, is adopted in this study. The nonlinear finite element analyses are conducted taking into account empty and full reservoir cases, to exhibit the hydrodynamic effect of reservoir water on the dam earthquake response. The hydrodynamic pressure is modeled by fluid finite elements based on a Lagrangian approach. Transient analyses take into account material and connection nonlinearity. Drucker-Prager model is employed in nonlinear analyses for the dam concrete and foundation rock. The structural crack between the top and bottom blocks of the dam is presented by surface-to-surface contact elements based on Coulomb’s friction law in order to simulate the behavior of contact joints and deformation of blocks. The distribution of horizontal displacements and principal stresses along the dam height is investigated for empty and full reservoir cases.The failure processes of two potential failure modes of cracked dam, i.e, the separation and sliding of top block during an earthquake, are examined.

5

Description of dispersed two-phase turbulent flow in the Lagrangian approach

72%

Pozorski J. , Minier J.-P.

Turbulence : international journal

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1998

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tom Vol. 4

7-32

EN

Turbulent two-phase participate flows are considered. Emphasis is put on the modelling issue and, in particular, on the class of models based on the Langevin equation. New model for particle dispersion in the Lagrangian approach is introduced. Physical arguments behind this model are quite different from those previously proposed in the literature, for some averaged characteristics of the relative motion of solid-fluid particle pairs are considered rather than instantaneous relative velocities. The model takes both particle inertia and external force effects into account. Its performance is examined by comparison with existing experimental data on particle dispersion in grid turbulence and with the outcome of a numerical experiment (the Large-Eddy Simulation). The obtained results are found to be satisfactory.