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2215. Nový britský Flood Estimation Handbook: rozšírená recenzia

Creator:
Čunderlík, Juraj
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
hydrology, Flood Estimation Handbook, pooling scheme, at-site and pooled estimation, N-year rainfalls and floods, hydrológia, regionálna typizácia, lokálny a regionálny odhad, and N-ročné zrážky a prietoky
Language:
Slovak
Description:
The recently published new British Flood Estimation Handbook (FEH) is a unique hydrological publication, giving guidance on rainfall and river flood frequency estimation in the United Kingdom. The FEH is an outcome of a five-year research programme at the Centre of Ecology and Hydrology in Wallingford. The FEH provides novel statistical and geostatistical methods and new hydrological approaches used for assessing the rarity of extreme rainfall and flood events. The publication is accompanied by software (WINFAP-FEH) and digital data (FLOOD DATA CD-ROM). The procedures are clearly explained, and supporting theory and examples are included. The FEH clearly deserves the attention of hydrologists around the world. The main objective of this review is to provide our hydrological community with a brief description of the major methodological approaches used in FEH for rainfall and flood frequency analysis. and Nedávno publikovaný nový britský Flood Estimation Handbook predstavuje vo svete jedinečnú hydrologicků príručku podávajúcu ucelený návod - smernicu pre odhad návrhových zrážok a prietokov vo Veľkej Briránii. Toto dielo je výsledkom päťročnej intenzívnej práce tímu odborníkov z Institute of Hydrology vo Wallingforde. Do príručky sú implementované najnovšie metódy matematickej štatistiky a geoštatistiky. Autori v nej tvorivo inovujú a dopĺňajú hlavné metodické postupy používané momentálně vo svete pri odhade N-ročných srážok a prietokov. Celý projekt má aj softverovú podobu. Príručka si zasluhuje oprávnenú pozornosť hydrológov a klimatológov, a preto hlavným cieľom tohto článku je aspoň veľmi stručne oboznámiť našu odbornú verejnosť s týmto významným dielom a priblížiť jej najvýznamnejšie metodické postupy analýzy extrémnych zrážok a prietokov.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2217. Numerical and physical model study of a vertical slot fishway

Creator:
Bombač, Martin, Novak, Gorazd, Rodič, Primož, and Četina, Matjaž
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
eddy viscosity, hydraulic model, numerical diffusion, numerical model PCFLOW2D, turbulence model, and vertical slot fishway
Language:
Slovak
Description:
This paper presents the results of an experimental and numerical study of a vertical slot fishway (VSF). A 2-D depth-averaged shallow water numerical model PCFLOW2D coupled with three different turbulent models (constant eddy viscosity, Smagorinsky and k - ε) was used. A detailed analysis of numerical parameters needed for a correct simulation of the phenomenon was carried out. Besides the velocity field, attention was paid to important hydraulic parameters such as maximum velocity in the slot region and energy dissipation rate ε in order to evaluate the performance of VSF. A scaled physical hydraulic model was built to ensure reliable experimental data for the validation of the numerical model. Simulations of variant configurations of VSF showed that even small changes in geometry can produce more fishfriendly flow characteristics in pools. The present study indicates that the PCFLOW2D program is an appropriate tool to meet the main demands of the VSF design.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2218. Numerical and physical modeling of water flow over the ogee weir of the new Niedów barrage

Creator:
Herrera-Granados, Oscar and Kostecki, Stanisław W.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
hydraulic similarity, Ogee weir, discharge coefficient, physical modeling, 2D and 3D numerical modeling, and cofferdam
Language:
Slovak
Description:
In this paper, two- and three-dimensional numerical modeling is applied in order to simulate water flow behavior over the new Niedów barrage in South Poland. The draining capacity of one of the flood alleviation structures (ogee weir) for exploitation and catastrophic conditions was estimated. In addition, the output of the numerical models is compared with experimental data. The experiments demonstrated that the draining capacity of the barrage alleviation scheme is sufficiently designed for catastrophic scenarios if water is flowing under steady flow conditions. Nevertheless, the new cofferdam, which is part of the temporal reconstruction works, is affecting the draining capacity of the whole low-head barrage project.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2219. Numerical investigation of solid-liquid slurry flow through an upward-facing step

Creator:
Messa, Gianandrea Vittorio and Malavasi, Stefano
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
two-fluid model, numerical analysis, slurries, two-phase flow, and upward-facing step
Language:
Slovak
Description:
The flow of a solid-water mixture through an upward-facing step in a channel is numerically investigated. The effect of expansion ratio, mean solids volume fraction and particle diameter on the velocity field, pressure distribution and solid volume fraction field is studied. Expansion ratios of 0.50 and 0.67, particle diameter of 125 µm and 440 µm and mean solid volume fraction between 0.05 and 0.20 are considered. Particle density is 2465 kg m-3 . An Eulerian twofluid model is used to simulate the flow. Due to the lack of experimental data, the model was validated by comparison to other numerical investigations and to experimental data about the horizontal pipe case. Afterwards, it is studied the effect of the above mentioned parameters upon the degree of coupling between the phases and the extension of the disturbance region in the pressure and solid volume fraction fields downstream the step. Parameters of engineering interest, such as the reattachment length and the pressure recovery downstream the enlargement, are investigated.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

2220. Numerical model of spherical particle saltation in a channel with a transversely tilted rough bed

Creator:
Lukerchenko, Nikolay, Piatsevich, Siarhei, Chára, Zdeněk, and Vlasák, Pavel
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
saltation, transversely tilted bed, particle-bed collision, particle sorting, saltace, příčně skloněné dno, kolise částice-dno, and třídění částic
Language:
Slovak
Description:
This paper deals with the numerical simulation of spherical particle saltation in a channel with a rough transversely tilted bed. The numerical model presented is based on the 3D model of spherical particle saltation developed by the authors, which takes into account the translational and rotational particle motion. The stochastic method and the concept of a contact zone were used for the calculation of a particle trajectory and its dependence on the bed lateral slope, particle diameter, and shear velocity. The effect of the bed lateral slope results in a deviation of the particle trajectory from the downstream direction. Some examples of the calculation are presented. The trajectories of the saltating particles starting their movements from one point were calculated and it was shown that they are of random character and together create a bundle or fascicle of trajectories. It was found that the centrelines of the bundles can be approximated by the straight lines for low and moderate values of the bed transverse slope, i.e. slopes less than 20°. The angle of deviation of the centreline from the downstream direction increases when the bed lateral slope and/or the particle diameters increase. However, with increasing shear velocity, the deviation angle decreases. Due to the lateral bed slope the particles are sorted according to their size, and the criteria for sorting particles were defined. An example of the particle sorting was calculated and the separable and nonseparable regions were determined. and Studie popisuje numerickou simulaci saltačního pohybu kulovité částice v korytě s příčně skloněným drsným dnem. Předložený numerický model je založen na autory vyvinutém 3D modelu saltačního pohybu kulovité částice, který počítá s translačním i rotačním pohybem částice. Pro výpočet trajektorie částice a její závislosti na příčném sklonu dna koryta, průměru částice a smykové rychlosti nosné kapaliny byla použita stochastická metoda a koncept kontaktní zóny. Vlivem příčného sklonu dna koryta dochází k odchylce trajektorie částice od směru proudu. Trajektorie částic začínajících svůj pohyb v jednom bodě byly vypočteny a bylo ukázáno, že trajektorie jsou náhodného charakteru a tvoří společně svazek trajektorií, jehož osa může být pro nízké a střední hodnoty příčného sklonu dna koryta aproximována přímkou. Vlivem příčného sklonu dna koryta může dojít k roztřídění částic podle velikosti. Bylo spočteno několik příkladů třídění, definováno kriterium třídění a určeny oblasti třídění podle velikosti částic a sklonu dna koryta.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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