Wyniki wyszukiwania dla: surface flow
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Application of a cellular automata model to granular flow
PublikacjaPrzedstawiono wyniki modelowania przepływów granulowanych przy zastosowaniu automatu komórkowego. Obliczenia wykonano dla silosów ze wstawkami i ścianką szczelną. Przyjęto różne schematy propagacji ziaren.
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Investigations of resonance effects during silo flow.
PublikacjaOmówiono problem efektów rezonansowych podczas przepływu materiału sypkiego w silosie. Wykonano badania doświadczalne w dużych i małych silosach. Obliczenia MES wykonano dla płaskiego stanu odkształcenia. Zachowanie materiału sypkiego było modelowane mikropolarnym sprężysto-plastycznym prawem wg Mh hausa. W obliczeniach uwzględniono wpływ ścian. Wyniki numeryczne porównano z doświadczeniami w dużych i małych silosach.
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Heat transfer intensification by jet impingement – numerical analysis using RANS approach
PublikacjaJet impingement is a method of the heat transfer enhancement applied in the engineering systems. The idea is to generate fast-flow fluid jet which impinge on the heated (or cooled) surface, causing significantly higher heat transfer rate. Although some flat surface jet impingement cases are described in the literature, the validated data is still limited. The reason is coming from the fact, that these flows are hydrodynamically...
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Long-term operation of Kickuth-type constructed wetland applied to municipal wastewater treatment in temperate climate
PublikacjaThe purpose of this paper is to discuss the problem of changes of effectiveness of Kickuth-type constructed wetland with subsurface flow applied to domestic wastewater treatment. This study is based on an example of a wetland 3000 m2 in surface, serving 800 inhabitants, located in Poland. The results of chemical analysis showed that after an initial year of ‘start-up time’, the efficiency of pollutant removal gradually increased...
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Numeryczna analiza hydrauliki toru kajakarstwa górskiego w Drzewicy
PublikacjaW artykule zaproponowano wykorzystanie do analizy hydrodynamiki toru kajakarstwa górskiego symulacji numerycznej, wykorzystującej dwuwymiarowe równania ruchu wody w warunkach przepływu szybkozmiennego. Rozwiązanie równań hydrodynamiki wykonano samodzielnie z zastosowaniem metody objętości skończonych. Jako przykład zastosowania zaproponowanej metody przedstawiono analizę przepływu wzdłuż istniejącego, poddanego modernizacji toru...
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Silo music — Mechanism of dynamic flow and structure interaction
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Numerical aspects of improvement of the unsteady pipe flow equations
PublikacjaW pracy dokonano analizy zaproponowanych w ostatnich latach metod opisu oporów ruchu w przepływie nieustalonym w przewodach pod ciśnieniem. Wykazano,że modyfikacja współczynnika oporów liniowych nie może zapewnić pozytywnych efektów oraz ,że poprawa wyników wykazywana przez autorów modyfikacji wynika z błędu dyfuzji numerycznej generowanej przez metodę rozwiązania.
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Two-dimensional vertical analysis of dam-break flow
PublikacjaW artykule przedstawiono matematyczne modelowanie przepływów ze swobodną powierzchnią w kanałach otwartych. Do symulacji przepływu użyto dwuwymiarowy pionowy model RANS. Wchodzące w skład modelu równania Naviera-Stokesa rozwiązano stosując algorytm SIMPLE dla metody różnic skończonych. Do śledzenia zmian swobodnego zwierciadła wody zastosowano metodę MAC. Analizie poddano szybkozmienny przepływ po poziomym, gładkim dnie wywołany...
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Spetiation of organic matter in Vertical Flow Constructed Wetlands
PublikacjaThe object of the research were VFCWs which are a component of biological treatment of two hybrid hydrophyte systems located in Wieszyno and Wiklino, close to Słupsk, Poland. The facilities that are subject to analyses are unified in terms of structure (filtration material, depth of the bed and time of operation), but they differ in organic matter load, amounting respectively to: 8.0 gCOD/m2day and 31.0 gCOD/m2day.The intensity...
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Modeling lubricant flow between thrust-bearing pads
PublikacjaInlet temperature is one of the main inputs in all models for the analysis of fluid film bearing performance. At the same time, inlettemperature distribution and also oil velocity distribution at the inlet are the result of flow phenomena in the gap between the bearingpads. These phenomena are complex and in many cases further affected by any special arrangements of forced oil supply to the gapbetween pads. The reason for such...
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Thermal heat-balance mode flow-to-frequency converter
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Steady magnetohydrodynamic flow in a diverging channel with suction or blowing
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Turbulence Flow Modeling of One-Sharp-Groyne Field
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Analysis of 5-Hydroxymethyluracil Levels Using Flow Cytometry
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NUMERICAL SIMULATIONS OF GAP FLOW ABOVE ROTATING DISK
PublikacjaA rotating disk can be considered a basic configuration for the investigati ons of the impact of various conditions on the flow through the clearance between the s hrouded turbine blade and the casing. Numerical calculations using Fine/Turbo Numeca were conducted to examine the influence of the rotational velocity and the pressure differ ence across the disk on the flow conditions, especially the mass flow through the clearance....
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Pawlak's flow graph extensions for video surveillance systems
PublikacjaThe idea of the Pawlak's flow graphs is applicable to many problems in various fields related to decision algorithms or data mining. The flow graphs can be used also in the video surveillance systems. Especially in distributed multi-camera systems which are problematic to be handled by human operators because of their limited perception. In such systems automated video analysis needs to be implemented. Important part of this analysis...
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Estimation of the steam condensation flow via CFD methods
PublikacjaThe results of numerical simulations to predict the performance of different steam models have been presented. All of the considered models of steam condensation have been validated on the base of benchmark experiment employing expansion in nozzle and next on the low pressure part of the steam turbine stage. For numerical analysis three models have been finally used – the ideal steam model without condensation, an equilibrium steam...
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EXPERIMENTAL AND THEORETICAL FLOW OF THE FORCES IN DEEP BEAMS WITH CANTILEVAR
PublikacjaThis article presents the results of experimental research carried out on deep beams with cantilever which was loaded throughout the depth. The main deep beam was directly simply supported on the one side. On the other side the deep beam was suspended in another deep member situated at right angles. All deep beams created a spatial arrangement. The paper is focused on the analysis of the cracks morphology and flow of the internal...
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A System for Cooling Electronic Elements with EHD Coolant Flow
PublikacjaA system for cooling electronic components where the liquid coolant flow is forced with ion-drag type EHD micropumps was tested.
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Experimental investigations on condensation in flow in small diameter channels
PublikacjaW pracy przedstawiono innowacyjne podejście do eksperymentalnych badań kondensacji w przepływie oraz omówiono wstępne wyniki badań eksperymentalnych kondensacji etanolu w pionowej rurce srebrnej o średnicy wewnętrznej 2.3 mm.
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Experimental Verification of Storm Sewer Transient Flow Simulation
PublikacjaThe paper focuses mainly on laboratory investigations of transient and transcritical flow in a single pipe of a sewer system. The aim of this paper is to present a comparison between pressure values calculated by an improved McCormack scheme and those measured at the hydraulic laboratory of the Gdansk University of Technology, which were observed inside a pipe in an experiment for water flow with pressurization. The analysis proves...
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Acoustic heating produced in the thermoviscous flow of a Bingham plastic
PublikacjaThis study is devoted to the instantaneous acoustic heating of a Bingham plastic. The model of the Bingham plastic's viscous stress tensor includes the yield stress along with the shear viscosity, which differentiates a Bingham plastic from a viscous Newtonian fluid. A special linear combination of the conservation equations in differential form makes it possible to reduce all acoustic terms in the linear part of of the final equation...
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GENERALISED HERSCHEL MODEL APPLIED TO BLOOD FLOW MODELLING
PublikacjaThis paper introduces a new rheological model of blood as a certain generalisation of the standard Herschel-Bulkley model. This model is a rheological constitutive equation and belongs to the group of the so-called generalised Newtonian fluids. Experimental data is compared with results, obtained from the new model, to demonstrate that it allows for the best agreement together with Luo-Kuang model. The new model may be easily implemented...
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Alternative convolution approach to friction in unsteady pipe flow
PublikacjaIn the paper some aspects of the unsteady friction in pipe flow expressed by the convolution are analyzed. This additional term introduced into the motion equation involves the accelerations of fluid occurring in the past and a weighting function. The essence of such approach is to assume the appropriate form of weighting function. However, until now no fully reliable formula for this function has been found. To avoid some inconveniences...
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Electrohydrodynamic secondary flow in the electrostatic precipitator with spiked electrodes
PublikacjaIn this work, the results of electrohydrodynamic (EHD) secondary flow measurements in an electrostatic precipitator (ESP) with one-sidedspike electrodes are presented. The EHD secondary flow was measured for one-sided spike electrodes with the spike tips directed either upstream or downstream the primary flow. The results showed different flow patterns for different spike tips direction in respect to the primary flow direction....
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Graphene field-effect transistor application for flow sensing
PublikacjaMicroflow sensors offer great potential for applications in microfluidics and lab-on-a-chip systems. However, thermal-based sensors, which are commonly used in modern flow sensing technology, are mainly made of materials with positive temperature coefficients (PTC) and suffer from a self-heating effect and slow response time. Therefore, the design of novel devices and careful selection of materials are required to improve the overall...
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CFD analysis of fluid flow through the labyrinth seal
PublikacjaSteam and gas turbines are some of the fundamental means of power generation. The energy efficiency of the turbines, however, is not satisfactory. Ever since the start-up of the first turbine in the world, engineers have been striving for their increased efficiency. Multiple solutions to the problem of steam loss in an operating turbine are available. The use of seals is one of them. Empirical methods or numerical calculations...
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Flow cytometric assessment of homeostatic aging of reticulocytes in rats
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Estimation of flow for tissue perfusion of nutrient liquids in bioreactor.
PublikacjaPrzedstawione zostały problemy związane z wyznaczaniem pola prędkości w warstwie przyściennej opływanej tkanki miękkiej w bioreaktorze. Warunki brzegowe na powierzchni miękkiej tkanki o właściwościach porowatych zostały w niniejszej pracy sformułowane.
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Tracer investigations of dynamic properties of fluid flow reactor.
PublikacjaOmówiono podstawowe metody opisu rozkładu czasu przebywania cieczy w reaktorze oraz sposób jego wyznaczania metodą znacznikową. Szczegółowo omówiono wyniki badań laboratoryjnych dla separatora substancji olejowych i dla złoża biologicznego.
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Modelling of flow boiling process in small diameter tubes.
PublikacjaW pracy zastosowano standardową korelację wrzenia w przepływie (wyprowadzoną dla rur o konwencjonalnych wymiarach) do przypadków wrzenia w rurach o małych średnicach. Porównanie wyników obliczeń z danymi literaturowymi wykazało nieużyteczność tej korelacji. Wykazano zatem potrzebę prowadzenia badań podstawowych celem uzyskania korelacji pozwalającej umiejętnie przewidywać warunki wymiany ciepła w kanałach o małych średnicach.
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Acoustic heating produced in the thermoviscous flow of a bingham plastic
PublikacjaThis study is devoted to the instantaneous acoustic heating of a Bingham plastic. The model of the Bingham plastic's viscous stress tensor includes the yield stress along with the shear viscosity, which differentiates a Bingham plastic from a viscous Newtonian fluid. A special linear combination of the conservation equations in differential form makes it possible to reduce all acoustic terms in the linear part of of the final equation...
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Hydrodynamics and heat transfer in bubbly flow in the turbulent boundarylayer
PublikacjaW pracy przedstawiono oryginalne podejście do modelowania przepływu pęcherzykowego w warstwie przyściennej i w kanale. Podejście oparte jest na sumowaniu energii dyssypacji pochodzącej od przepływu ścinającego w kanale oraz dyssypacji pochodzącej od obecności pęcherzyków. W wyniku otrzymuje się naprężenia styczne ekwiwalentnego przepływu jednofazowego. Zaproponowano własne podejście do modelowania stopnia zapełnienia opisane równaniem...
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Dedicated scheduling of tasks to minimize mean flow time
PublikacjaThis paper investigates the complexity of scheduling biprocessor tasks on dedicated processors to minimize mean flow time. Since the general problem is strongly NP-hard, we assume some restrictions on task lengths and the structure of associated scheduling graphs. Of particular interest are acyclic graphs. In this way we identify a borderline between NP-hard and polynomially solvable special cases.
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Modeling of flow phenomena associated with polymer injection into a mold
PublikacjaPodczas wtrysku tworzywa do formy w strefie tworzywo-ścianka formy występują zjawiska, które są źródłem zwiększonej chropowatości powierzchni i wad wypraski. W pracy pisano powyższe zjawiska oraz zaprezentowano model numeryczny, umożliwiający symulację tych zjawisk. Symulację komputerową wykonano w CI TASK stosując program FIDAP. Wyniki badań symulacyjnych zweryfikowano badaniami doświadczalnymi, wykonując fotografie i profilogramy...
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Flow boiling of oil-refrigerant mixtures in smooth tubes
PublikacjaPrzedstawiono wyniki badań współczynnika przejmowania ciepła i spadku ciśnienia podczas wrzenia czynników R 22, R 134a i R 407C i ich mieszanin z olejem w rurach gładkich. Opisano procedurę badawczą. Udział masowy oleju w mieszaninie z czynnikiem wynosił 0,1% i 5%. Zaobserwowano negatywny wpływ obecności środka smarnego we wrzącym czynniku chłodniczym.
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Flow-induced stress corrosion failure of SS piping
PublikacjaPrzedstawiono uszkodzenie eksploatacyjne rurociągu ze stali austenitucznej typu 18Cr-10Ni-Ti w instalacji przepracowanych olejów napędowych w rafinerii ropy naftowej. Wyjaśniono mechanizm niszczenia środowiskowego stali w wyniku mechanicznego i elektrochemicznego działania strumieni procesowych.
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Steady magnetohydrodynamic flow in a diverging channel with suction or blowing
PublikacjaAn analysis is made of steady two-dimensional divergent flow of an electrically conducting incompressible viscous fluid in a channel formed by two non-parallel walls, the flow being caused by a source of fluid volume at the intersection of the walls. The fluid is permeated by a magnetic field produced by an electric current along the line of intersection of the channel walls. The walls are porous and subjected to either suction...
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Experimental investigations of R22 flow boiling in enhanced tubes.
PublikacjaPrzedstawiono wyniki badań eksperymentalnych wrzenia R22 podczas wrzenia w przepływie wewnątrz rur o rozwiniętej powierzchni przejmowania ciepła: miedzianej rury niskożebrowanej wewnętrznie, stalowej rury formowanej śrubowo oraz stalowej rury z pokryciem porowatym. Przeprowadzono także badania na dwóch rurach gładkich, o średnicy odpowiadającej maksymalnej średnicy wewnętrznej rur o rozwiniętej powierzchni. Średnie wartości...
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Discrete-continuous optimisation of an axial flow blood pump
PublikacjaThis paper presents results of discrete-continuous optimisation of an axial flow blood pump. Evolution Strategies (ES) are used as a global optimisation method in order to localise the optimal solution in relatively short time. The whole optimisation process is fully automated. This also applies to geometry modelling. Numerical simulations of the flow inside the pump is performed by means of the Reynolds-Average Navier-Stokes...
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Educational Dataset of Handheld Doppler Blood Flow Recordings
PublikacjaVital signals registration plays a significant role in biomedical engineering and education process. Well acquired data allow future engineers to observe certain physical phenomena as well learn how to correctly process and interpret the data. This dataset was designed for students to learn about Doppler phenomena and to demonstrate correctly and incorrectly acquired signals as well as the basic methods of signal processing. This...
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Inverse Flood Routing Using Simplified Flow Equations
PublikacjaThe paper considers the problem of inverse flood routing in reservoir operation strategy. The aim of the work is to investigate the possibility of determining the hydrograph at the upstream end based on the hydrograph required at the downstream end using simplified open channel flow models. To accomplish this, the linear kinematic wave equation, the diffusive wave equation and the linear Muskingum equation are considered. To achieve...
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Modeling of entrained flow steam gasification of sewage sludge
PublikacjaProper management of sewage sludge becomes increasingly problematic due to legal requirements aiming at diminishing environmental impact, as well as rationalizing the utilization from the point of view of logistics. Steam gasification of sewage sludge can result in very good quality of the producer gas. So far, the works have been focused on the gasification in fixed bed gasifiers. However, this does not allow to take full advantage...
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Analysis of the radiation dose in UV-disinfection flow reactors.
PublikacjaTheoretical considerations devoted to the variation of UV radiation doses in flow disinfection reactors are presented. The minimal time required by the fluid to pass the reactor was determined and combined with the radiation intensity. The active zones of the reactor were determined.
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River flow simulation based on the HEC-RAS system
PublikacjaThis work considers the problem of river floods, and presents a computer solution that can be used to predict such a threat. The basic tool, called Hydrologic Engineering Centers for River Analysis System (HEC-RAS), and created by the US Army Corps of Engineering, is well developed; and the models created in the system HEC-RAS are quite realistic. For the purpose of solving practical national flood problems, simplified static and...
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River Flow Simulation Based on the HEC-RAS System
PublikacjaThis work considers the problem of river floods, and presents a computer solution that can be used to predict such a threat. The basic tool, called Hydrologic Engineering Centers for River Analysis System (HEC-RAS), and created by the US Army Corps of Engineering, is well developed; and the models created in the system HEC-RAS are quite realistic. For the purpose of solving practical national flood problems, simplified static and...
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A Concept of Freight Traffic Flow Regulations in the City of Gdansk
PublikacjaThis paper presents a review of state-of-art efforts in urban freight transport modelling in the context of their requirements and applicability as a basis for evaluation of city's freight transport policy. Freight transport mirrors all aspects of the city's economic activity and for that reason its proper planning is of extreme importance. However, urban freight system may be considered as the most varied and fragmented element...
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CFD Simulations and Tests of a Prototype Flow Control Valve
PublikacjaIn this paper a prototype of a flow control valve is described and numerically simulated. The flow control valve is used in hydraulic systems to maintain constant fluid flow despite changing loads of a receiver. The standard construction of this type of valves is modified mainly by eliminating the spring. The prototype consists the hydrostatically unloaded throttle valve and pressure ratio valve substituting pressure difference...
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Material Flow Analysis in a cooked mussel processing industry
PublikacjaGalicia (NW Spain) is an ideal environment for mussel culture owing to its excellent natural conditions. It is the first Spanish and European mussel producer and the second worldwide after China. More than 50% of the mussel collected in Galicia is used in the processing industry, which produces different products, as cooked mussel that is canned, frozen or used in the food industry. In this paper a methodology based on Life Cycle...
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MODEL FOR MEASUREMENT OF FLOW INSTALLATION TIME IN SDN SWITCH
PublikacjaSDN is the approach in telecommunication networks that separates control plane from data forwarding plane by specifying a single network entity as a controller that defines rules (called flows) of traffic forwarding for the switches connected to it. The time that is required for installation of these rules might be a hindrance for the overall performance of SDN network. In the paper, a model for testing and evaluating the influence...