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8632. NTproBNP u seniorov – iniciálny pohľad z reálnej klinickej praxe
- Creator:
- Zhuková, D., Dolanová, N., Jánošiová, J., and Dúbrava, Martin
- Format:
- print, text, and regular print
- Type:
- model:article, article, Text, abstrakt z konference, and TEXT
- Language:
- Czech and Slovak
- Description:
- D. Zhuková, N. Dolanová, J. Jánošiová, M. Dúbrava
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
8633. 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
8634. 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
8635. 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
8636. 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
8637. Numerical modelling of hydrodynamics and sediment transport processes during storm events in a non-perennial river
- Creator:
- Ramsankaran, Raaj, Maerker, Christian, and Malcherek, Andreas
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- runoff event modelling, SediMorph, sediment transport, TELEMAC-2D, modelovanie odtoku, and transport sedimentov
- Language:
- Slovak
- Description:
- This article presents the numerical modelling of hydrodynamics and sediment transport processes in the seasonal Pathri Rao River, which flows in the Northern part of India. Modelling is made by the coupled application of the hydrodynamic model called TELEMAC-2D and the morphodynamic model called SediMorph. The hydrodynamic model results are validated with the observed data and it has been found that the present model provides reasonable predictions. Likewise, the validation of the morphodynamic model is also presented. For this purpose, the suspended and bed load transport modules are validated separately for four runoff events observed during the investigations. The validation of the former is approached by comparing the depth-averaged suspended transport concentrations against experimental measurements made at the make-shift gauging station and subsequent comparison against experimental measurements. On the other hand, due to non-availability of the observed values on bed load sediment transport, the bed load sediment transport and bed evolution numerical results could not be validated quantitatively and was approached only on qualitative basis. In general, both validations present an acceptable agreement with measurements and scientific facts. Further, this study demonstrates that the coupled TELEMAC-2D/SediMorph system could be used with confidence for practical applications in the Pathri Rao River. and Príspevok obsahuje výsledky numerického modelovania hydrodynamických javov a transportu sedimentov v občasnom toku Pathri Rao, v severnej časti Indie. Procesy boli modelované zdvojenou aplikáciou hydrodynamického modelu TELEMAC-2D a morfodynamického modelu SediMorph. Výsledky modelovania hydrodynamickým modelom boli verifikované s využitím pozorovaných hodnôt; bolo zistené, že model dáva akceptovateľné výsledky. Prezentuje sa tiež verifikácia morfodynamického modelu. Počas epizód odtoku bol transport suspendovaných častíc a častíc transportovaných po dne toku verifikovaný osobitne. Verifikácia transportu suspendovaných častíc bola uskutočnená porovnaním hĺbkovo spriemerovanými koncentráciami suspendovaných častíc s meranými hodnotami na prietokomerných staniciach. Pre nedostatok pozorovaných údajov o dnovom transporte, údaje o ňom a o zmenách morfológie toku mohli byť verifikované len kvalitatívne. Záverom, obe verifikácie dali akceptovateľnú zhodu s výsledkami meraní a existujúcimi vedeckými poznatkami. Okrem toho výsledky štúdie demonštrujú schopnosť zdvojených modelov TELEMAC-2D/SediMorph získavať spoľahlivé výsledky pri aplikácii na rieke Pathri Rao.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8638. Numerical modelling of the velocity distribution in a compound channel
- Creator:
- Othman, F. and Valentine, E. M.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- compound channel, Navier-Stokes equation, non-linear k-ε turbulence model, reynolds stress model (RSM), velocityc distribution, secondary currents, zložený profil, rovnice Naviera-Stokesa, nelineárny k-ε model turbulencie, model Reynoldsových napätí (RSM), rozdelenie rýchlostí, and druhotné prúdy
- Language:
- Slovak
- Description:
- Uniform flow in compound channels has been studied in terms of a numerical model, called the NKE model. The model uses the three dimensional Navier-Stokes equations in conjunction with the non-linear k-ε turbulence model. The latter is used for the calculation of the Reynolds stress components responsible for the generation of the secondary currents. This model is based on the SIMPLE technique, and computes the six parameters U, V, W, P, k, and ε using wall functions on a Cartesian grid. The NKE model was used to simulate the compound open channel flows of the UK Flood Channel Facility run 080301 (Shiono and Knight, 1989). The Reynolds Stress Model (RSM) of FLUENT was also used as a comparison. The results obtained have shown that the NKE and RSM models can reasonably predict the primary mean velocity and secondary currents. Although agreement is certainly not perfect in every detail, the main features of the flow are reproduced. The bulging of the contours at the bottom corner of the main channel, the inclination of the contours near the free surface towards the channel centre, and the depression of the maximum velocity below the free surface can be seen. These are consistent with the pattern of the secondary flows, which are mainly formed by two vortices, namely the main channel vortex and flood plain vortex. These vortices, which originate near the main channel-flood plain junction, can be reproduced by the NKE and RSM models. and Štúdia pomocou numerického modelu NKF analyzuje ustálený rovnomerný prúd vody v koryte zloženom z kinety a dvoch symetrických beriem so zvislými stranami. Model využíva tri rovnice Naviera- Stokesa a nelineárny k-ε model turbulencie, ktorý simuluje Reynoldsove napätia, zodpovedné za druhotné prúdy. Tento model, založený na tzv. SIMPLE technike, počíta šesť parametrov U, V, W, P, k a ε pri použití stenových funkcií a karteziánskej siete. NKE model simuloval prúdenie, experimentálne pozorované na zariadení UK Flood Channel Facility ako séria č. 080301 (Shiono a Knight, 1989). Model pre Reynoldsove napätia (RSM) z balíka FLUENT bol tiež využitý na porovnanie. Výsledky ukázali, že modely NKE a RSM sú schopné predpovedať ako základné rýchlostné pole, tak aj vyvolané druhotné prúdenia. Aj keď zhoda s experimentom nie je v každom detaile úplná, hlavné znaky rýchlostného poľa sú zobrazené. Na simulácii možno vidieť zaoblenie rýchlostného poľa v rohoch dna hlavného kanála, sklon poľa v blízkosti hladiny smerom do stredu, ako aj pokles maxima rýchlosti pod voľnú hladinu. Tieto efekty sú v súlade s obrazom druhotných prúdov, ktoré sú tvorené hlavne dvoma vírmi - vírom kinety a vírom bermy. Tieto víry, vznikajúce pri spojení kinety s bermou, môžu byť reprodukované modelmi NKE a RSM.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
8639. Numerical modelling of two-layer shallow water flow in microtidal salt-wedge estuaries: Finite volume solver and field validation
- Creator:
- Krvavica, Nino, Kožar, Ivica, Travaš, Vanja, and Ožanić, Nevenka
- Type:
- article, model:article, and TEXT
- Subject:
- finite volume method, q-schemes, salt-wedge estuaries, two-layer flows, shallow water equations, and Rječina Estuary
- Language:
- Slovak
- Description:
- A finite volume model for two-layer shallow water flow in microtidal salt-wedge estuaries is presented in this work. The governing equations are a coupled system of shallow water equations with source terms accounting for irregular channel geometry and shear stress at the bed and interface between the layers. To solve this system we applied the Qscheme of Roe with suitable treatment of source terms, coupling terms, and wet-dry fronts. The proposed numerical model is explicit in time, shock-capturing and it satisfies the extended conservation property for water at rest. The model was validated by comparing the steady-state solutions against a known arrested salt-wedge model and by comparing both steady-state and time-dependant solutions against field observations in Rječina Estuary in Croatia. When the interfacial friction factor was chosen correctly, the agreement between numerical results and field observations was satisfactory.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
8640. Numerical simulation of fly-ash transport in three sands of different particle-size distributions using HYDRUS-1D
- Creator:
- Kodešová, Radka, Kapička, Aleš, Lebeda, Jakub, Grison, Hana, Kočárek, Martin, and Petrovský, Eduard
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- sand, fly-ash migration, magnetic susceptibility, numerical simulation, attachment/detachment concept, filtration theory, písek, migrace úletového popílku, magnetická susceptibilita, numerická simulace, attachment/detachment koncept, and filtrační teorie
- Language:
- Slovak
- Description:
- Study is focused on the numerical modeling of fly-ash transport in three sands, which was experimentally studied in the laboratory. Sands were packed in glass cylinders with diameter of 5.52 cm and height of 18 cm. Sands were also packed in plastic cylinders with diameter of 30 cm and height of 40 cm. The fly-ash and pulse infiltrations were applied on the top of all cylinders. Visually observed and gravimetrically evaluated fly-ash migration in small cylinders corresponded to fly-ash mobility in large columns detected using the SM400 Kappameter. The HYDRUS-1D code was used to simulate observed fly-ash transport. Parameters of soil hydraulic functions were either obtained using the Tempe cells and the RETC program or estimated using numerical inversion of transient water flow data measured in both types of columns using HYDRUS-1D. Parameters characterizing colloid transport in sands were then estimated from the final fly-ash distribution in sandy columns using attachment/detachment concept in HYDRUS-1D. Fly-ash mobility increased with increasing sand particle sizes, e.g. pore sizes. Particle sizes and pore water velocity influenced the attachment coefficient, which was calculated assuming filtration theory. The same longitudinal dispersivity, sticking efficiency and detachment coefficient sufficiently characterized fly-ash behavior in all sands. and Studie je zaměřena na numerické modelování transportu úletového popílku ve třech píscích, který byl experimentálně studován v laboratoři. Písky byly nahutněny ve skleněných válcích o průměru 5,52 cm a výšce 18 cm. Písky byly také nahutněny v plastových válcích o průměru 30 cm a výšce 40 cm. Na povrchu válců byly aplikovány jednorázové infiltrace vody s popílkem. Migrace úletového popílku pozorovaná vizuálně a zjištěná gravimetricky v malých válcích odpovídala mobilitě úletového popílku detekované Kappametrem SM400 ve velkých válcích. Pozorovaný transport úletového popílku byl simulován programem HYDRUS-1D. Parametry hydraulických funkcí byly získány buď pomocí Tempských cel a programu RETC nebo odhadovány numerickou inverzí transientních data měřených na obou typech válců programem HYDRUS-1D. Parametry charakterizující transport koloidů v píscích byly potom odhadovány z konečné distribuce úletového popílku v písčitých sloupcích užitím konceptu attachment/detachment (připojení/odpojení) v programu HYDRUS-1D. Mobilita úletového popílku se zvyšovala se zvyšující se velikostí písčitých zrn, tj. s velikostí pórů. Velikost zrn a pórová rychlost ovlivnila depoziční (attachment) koeficient, který byl počítán na základě filtrační teorie. Stejné hodnoty podélné disperze, efektivity blokování (sticking efficiency) a mobilizačního (detachement) koeficientu charakterizovaly chování úletového popílku ve všech píscích.
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public