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Využití meteorologických dat v hydrologickém modelování na příkladu malého povodí horní Vydry
Vlček, Lukáš; Šípek, Václav
2019 - Czech
Příspěvek se zabývá hodnocením malého výzkumného povodí tvořeným dvěma dominantními půdními typy (kryptopodzol, organozem) pramenné oblasti Vydry. Hydrometeorologická a hydropedologická měření jsou doplněná hydrologickým modelem HBV ve snaze odhadnout míru zapojení různých složek povrchového a podpovrchového proudění vody a jejich vliv na odtokový proces. Data byla získána přímým měřením v terénu v průběhu 5-ti hydrologických let (2013-2017). Jde o data půdní vlhkosti odvozené z ret. křivek a z měření potenciálu půdní vody ve dvou hloubkách (20 a 60 cm) na dvou lokalitách, hladiny podzemní vody na 5 místech ve vrchovišti. Vodní stav byl měřen automaticky v závěrovém profilu a také manuálně u dvou pramenů.\nPomocí hydrologického modelu došlo k uspokojivé reprezentaci srážko-odtokového procesu v povodí, režimu půdní vody i kolísání podzemní vody ve svrchní části vrchoviště (organozemi). Celkově je větší množství odtoku z povodí generováno z organozemi a to zejména díky nižší evapotranspiraci rašeliniště oproti ploše kryté kryptopodzolem. V suchých periodách naopak většina odtoku pochází z organominerální půdy (v této studii kryptopodzol) a organozem se na odtoku podílí jen pomalým výtokem ze spodní, dlouhodobě nasycené zóny (část katotelmu).\n This paper deals with an evaluation of runoff formation at a small catchment (0.6 km2) consisting of two dominant soil types of the Vydra headwaters. Several Hydro-meteorological parameters have been measured at the study catchment and used in a hydrological model in an effort to estimate a proportion of surface or subsurface flow components and their effects on the outflow process. Chosen hydrological model showed that a greater proportion of an outflow from the catchment is generated, in general, from a peat bog area, mainly due to the lower evapotranspiration from the peatland compared to the mineral soil. On the contrary, during dry periods most of the outflow comes from a mineral soil and a peat bog contributes only to the outflow from the lower, permanently saturated layer.
Keywords:
runoff generation; peat bog; soil; Šumava mountains
Available at various institutes of the ASCR
Využití meteorologických dat v hydrologickém modelování na příkladu malého povodí horní Vydry
Příspěvek se zabývá hodnocením malého výzkumného povodí tvořeným dvěma dominantními půdními typy (kryptopodzol, organozem) pramenné oblasti Vydry. Hydrometeorologická a hydropedologická měření jsou ...
Local velocity scaling in upward flow to tooth impeller in a fully turbulent region
Šulc, R.; Ditl, P.; Fořt, I.; Jašíková, D.; Kotek, M.; Kopecký, V.; Kysela, Bohuš
2018 - English
The hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical flat bottom vessel 400 mm in inner diameter agitated by a tooth impeller 133 mm in diameter. Distilled water was used as the agitated liquid. The velocity fields were investigated in the upward flow to the impeller for three impeller rotation speeds – 300 rpm, 500 rpm and 700 rpm, corresponding to a Reynolds number in the range 94 000 < Re < 221 000. This means that fully-developed turbulent flow was reached. This Re range secures the fully-developed turbulent flow in an agitated liquid. In accordance with the theory of mixing, the dimensionless mean and fluctuation velocities in the measured directions were found to be constant and independent of the impeller Reynolds number. On the basis of the test results the spatial distributions of dimensionless velocities were calculated. The axial turbulence intensity was found to be in the majority in the range from 0.4 to 0.7, which corresponds to the middle level of turbulence intensity.
Available at various institutes of the ASCR
Local velocity scaling in upward flow to tooth impeller in a fully turbulent region
The hydrodynamics and flow field were measured in an agitated vessel using 2-D Time Resolved Particle Image Velocimetry (2-D TR PIV). The experiments were carried out in a fully baffled cylindrical ...
Plasty v pitné vodě
Čermáková, Lenka; Novotná, Kateřina; Peer, Petra; Janda, V.; Pivokonský, Martin
2018 - Czech
Výzkum byl zaměřen na výskyt mikroplastů ve zdrojích vody a v samotné pitné vodě. V poslední době je téma výskytu plastů ve vodě velice aktuální. Většina prací je včak zaměřena na kvantifikaci mikroplastů ve vodě mořské, sedimentech či povrchových vodách, které nejsou zdrojem surové vody pro úpravu na vodu pitnou, a zároveň se téměř vždy zabývají analýzou částic ve velikostním rozmezí 0,3-5 mm. Předmětem předkládané studie bylo kvantifikovat mikroplasty již od velikosti 0,2 μm, a to v surové a upravené vodě ze třech nejmenovaných úpraven vody v České republice, určit jejich velikostní distribuci, tvar a materiálové složení. Bylo zjištěno, že v závislosti na zdroji vody a technologii dané úpravny se počet mikroplastů pohyboval v rozmezí 1414-7006 částic I-1 v surové vodě a 305-921 částic I-1 ve vodě upravené. Velikostně dominovaly částice menší než 10 μm a tvarově ve dvou zdrojích fragmenty a v jednom zdroji vlákna. Z hlediska materiálového složení analyzovaných mikroplastů převládal poyethylentereftalát a polypropylén. The research was focused on microplastics occurring in water sources and in drinking water. Recently, the topic of microplastics in water is very up to date. However, most of the studies are focused on quantification of microplastics in sea water, sediments or surface waters, which are not a source of raw water for drinking water treatment, and at the same time the most of studies deal with the analysis of particles in the size range of 0.3 - 5 mm. The subject of the present study was to quantify microplastics from 0.2 μm in raw and treated water from three unnamed water treatment plants in the Czech Republic and to determine their size distribution, shape and material composition. It has been found that the number of microplastics ranged from 1414-7006 L-1 particles in raw water and 305-921 L-1 particles in treated water. Microplastics smaller than 10 μm were the most plentiful in both raw and treated water samples. Fragments clearly prevailed at two of the water treatment plants and fibres together with fragments predominated at one case.
Keywords:
microplastics; drinking water; water treatment; raw water
Available at various institutes of the ASCR
Plasty v pitné vodě
Výzkum byl zaměřen na výskyt mikroplastů ve zdrojích vody a v samotné pitné vodě. V poslední době je téma výskytu plastů ve vodě velice aktuální. Většina prací je včak zaměřena na kvantifikaci ...
Droplets breakage in flow conditions of an agitated tank
Kysela, Bohuš; Konfršt, Jiří; Chára, Zdeněk; Šulc, R.; Kotek, M.
2018 - English
Production of two immiscible liquid dispersions used in chemical or metallurgical industry is usually performed by a mixing process. The droplets of secondary liquid are predominantly dispersed by the shear flow forces to the primary liquid. It is well known, that the real droplet size distribution is limited by the physical properties of both liquids, the acting forces and residence time. This phenomenon is investigated experimentally or numerically simulated by several methods. In this study, the simplified mixing test case was studied. The single droplet dispergation was simulated using finite volume method and multiphase VOF (Volume-of-Fluid) model. The capability of the local remeshing method was investigated. The increase of calculation performance and the phases mass imbalance during automatic mesh refinement is summarized.
Keywords:
immiscible liquid dispersion; mixing process; droplet size distribution
Available at various institutes of the ASCR
Droplets breakage in flow conditions of an agitated tank
Production of two immiscible liquid dispersions used in chemical or metallurgical industry is usually performed by a mixing process. The droplets of secondary liquid are predominantly dispersed by the ...
Vliv organických látek na charakter agregátů tvořených koagulací/flokulací při úpravě vody
Filipenská, Monika; Pivokonská, Lenka; Vašatová, Petra; Pivokonský, Martin
2018 - Czech
Cílem práce bylo popsat vliv různých znečišťujících příměsí (kaolinitové částice, COM peptidy/proteiny a jejich směs) na velikost, velikostní distribuci, tvar a strukturu agregátů tvořených v proměnných hydrodynamických podmínkách (různá gradient rychlosti) v konečné fázi vývoje agregace, tzv. steady state. Jako míchací zařízení byl zvolen Taylor-Couettův reaktor, který umožňuje neinvazivní pozorování agregátů. Vlastnosti agregátů byly vyhodnocovány metodou obrazové analýzy. Bylo zjištěno, že velikost a tvar agregátů je závislá na typu koagulačního činidla, typu koagulované přímesi a aplikovaném gradientu rychlosti. Železité koagulační činidlo produkuje větší a méně pravidelné agregáty než činidlo hlinité. Podle příměsi roste velikost (zároveň klesá kompaktnost a roste neuspořádanost) agregátů v pořadí kaolinit < COM < kaolinit + COM. Bylo zjištěno, že velikost agregátů se na aplikovaném gradientu rychlosti nemění plynule, jak bylo doposud předpokládání, ale při překročení hodnoty tzv. kritických gradientů rychlosti, dochází k její prudké změně. Změny ve velikosti agregátů se liší v závislosti na charakteru koagulovaných příměsí a byly vysvětleny pomocí rozdílných interakcí mezi znečišťující příměsí a koagulačním činidlem. Characteristics of aggregates (size, shape, density and porosity) affect separation efficiency. These characteristics come from properties of impurities (molecular weight and structure, charge density, affinity to water, etc.), coagulation parameters (pH, type and concentration of coagulants, etc.) and by physical conditions (shear rate and time of mixing). In this work, we describe relations between the size of aggregates and shear rate and moreover dependency on the characteristics of coagulated compounds. In order to understand dependency on compounds, flocs formed by kaolinite, Algal Organic Matter (AOM) and a mixture of the same were studied. There was found aggregates are bigger and more porous when AOM is present. The most striking result is that aggregates size changes in dependence on shear rate are not smooth in progress. A rapid change for the kaolinite-coagulant suspension and two rapid changes for the suspensions containing AOM were observed. These were attributed to various intermolecular interactions between floc components participating in coagulation at the different shear rate.
Keywords:
AOM; Algal Organic Matter; coagulation; aggregation; shear rate; aggregate structure; water treatment
Available at various institutes of the ASCR
Vliv organických látek na charakter agregátů tvořených koagulací/flokulací při úpravě vody
Cílem práce bylo popsat vliv různých znečišťujících příměsí (kaolinitové částice, COM peptidy/proteiny a jejich směs) na velikost, velikostní distribuci, tvar a strukturu agregátů tvořených v ...
Dispersion kinetics in mechanically agitated vessel
Bucciarelli, E.; Formánek, R.; Kysela, Bohuš; Fořt, I.; Šulc, R.
2018 - English
Agitation of two immiscible liquids or solid-liquid suspension is a frequent operation in chemical and metallurgical industries. Prediction of mean drop/particle size and drop/particle size distribution (DSD) is vital for emulsification, suspension polymerization, solid particle dispersion or crystallization. Simulation of particulate systems requires the knowledge of DSD and its time evolution. The time evolution of drop size distribution was investigated in baffled vessel mechanically agitated by a Rushton turbine and a high-shear tooth impeller. The system water –silicone oil was used as a model liquid. The volume fraction of the dispersed phase was 0.047 %. The drop sizes were determined by image analysis. The time evolution of the drops size dp32 was studied for both impellers tested. The model used involves the first order kinetics. Finally, the following correlations predicted by the Kolmogorov-Hinze theory were evaluated at steady state: dp32/D = C1.We-0.6 and dpmax/D = C2.We-0.6, where We is the impeller Weber number.
Available at various institutes of the ASCR
Dispersion kinetics in mechanically agitated vessel
Agitation of two immiscible liquids or solid-liquid suspension is a frequent operation in chemical and metallurgical industries. Prediction of mean drop/particle size and drop/particle size ...
Measurement of drop size distribution time rate for liquid-liquid dispersion using IPI method
Jašíková, D.; Kotek, M.; Kysela, Bohuš; Šulc, R.; Kopecký, V.
2018 - English
The liquid-liquid dispersion properties are studied mainly by image analysis (IA) and Interferometric Particle Imaging (IPI). Drop sizes will be investigated in dilute dispersion since in this case the break up phenomena is the dominating and is not affected by phase fraction. Characteristics of the size distribution and the evolution of two liquid-liquid phase’s disintegration were studied. The IPI method was used for subsequent detailed study of the disintegrated droplets. We compared two liquids: Rhodosil Oil 47V50, and Silicone Oil AP1000 under stirrer rate of 540 rpm, and 760 rpm. The experiment run in the scaled model of agitated tank with Rushton turbine.
Available at various institutes of the ASCR
Measurement of drop size distribution time rate for liquid-liquid dispersion using IPI method
The liquid-liquid dispersion properties are studied mainly by image analysis (IA) and Interferometric Particle Imaging (IPI). Drop sizes will be investigated in dilute dispersion since in this case ...
Vodní režim v minulosti a současnosti – postřehy k zamyšlení
Buchtele, Josef; Slámová, Romana; Chlumecký, M.
2018 - Czech
The variability of the water regime is ascertained as being influenced by the frequent natural evolutions in the span of decades and also by some abrupt changes in the recent periods, including the damages or grows of vegetation cover or human influence in the historical decades. Analysis of such natural or man-made impacts in the context of historical evolution could clarify uncertainties and oscillations in basin water regime. The events as changes in vegetation cover, resp. evapotranspiration, land-use changes, building of new reservoirs and disappearing the old ones, effect of water management changing the condition of the water supply should be evaluated taking into account the influencing of the natural water regime. The modeling of rainfall-runoff process could be used to identify such impacts, especially for the cases when the long term complex monitoring is missing. The difference between observed and simulated streams flow appears as the helpful tool for the assessments of the resulting water regime. The variability of the water regime is ascertained as being influenced by the frequent natural evolutions in the span of decades and also by some abrupt changes in the recent periods, including the damages or grows of vegetation cover or human influence in the historical decades. Analysis of such natural or man-made impacts in the context of historical evolution could clarify uncertainties and oscillations in basin water regime. The events as changes in vegetation cover, resp. evapotranspiration, land-use changes, building of new reservoirs and disappearing the old ones, effect of water management changing the condition of the water supply should be evaluated taking into account the influencing of the natural water regime. The modeling of rainfall-runoff process could be used to identify such impacts, especially for the cases when the long term complex monitoring is missing. The difference between observed and simulated streams flow appears as the helpful tool for the assessments of the resulting water regime.
Keywords:
water regime; climate change; water resources
Available at various institutes of the ASCR
Vodní režim v minulosti a současnosti – postřehy k zamyšlení
The variability of the water regime is ascertained as being influenced by the frequent natural evolutions in the span of decades and also by some abrupt changes in the recent periods, including the ...
Modelling of non-monotonous course of shear viscosity
Filip, Petr
2018 - English
A number of parameters appearing in the 'classical' empirical constitutive equations usually oscillate between two and five. With the onset of new rheologically more complex materials exhibiting non-monotonous behaviour of flow curves this range (2-5) is no longer tenable and more additional parameters are required for a proper description of the flow curves. An 8-parameter model is presented and testified.
Keywords:
viscosity; flow curve; constitutive equation; empirical modelling
Available at various institutes of the ASCR
Modelling of non-monotonous course of shear viscosity
A number of parameters appearing in the 'classical' empirical constitutive equations usually oscillate between two and five. With the onset of new rheologically more complex materials exhibiting ...
Redukce šumu z experimentálních časových řad
Chára, Zdeněk; Kysela, Bohuš
2018 - Czech
Příspěvek se zabývá redukcí šumu z časových řad. Pozornost je zaměřena především na časové řady získané metodou PIV. Metoda redukce šumu je testována pro PIV data získaná při měření rychlostních polí v míchané nádobě. This article deals with the denoising of experimental time series. Attention is focused primarily on the time series obtained by the PIV method. The noise reduction method is tested for the PIV data obtained by measuring the velocity fields in the stirred vessel.
Keywords:
denoising; PIV; time series
Available at various institutes of the ASCR
Redukce šumu z experimentálních časových řad
Příspěvek se zabývá redukcí šumu z časových řad. Pozornost je zaměřena především na časové řady získané metodou PIV. Metoda redukce šumu je testována pro PIV data získaná při měření rychlostních polí ...
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