Wyniki wyszukiwania - Biblioteka Nauki

1

CFD simulation of short and long annular seals

100%

Kundera C. , Korczak A. , Zahorulko A. , Gerasimiva K. , Plykin M.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Nauki Techniczne

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2008

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tom Z. 7

77-89

2

Modelowanie CFD wypływu kropli z dystrybutora

80%

Sawiński W. , Feder-Kubis J. , Ludwig W.

Inżynieria i Aparatura Chemiczna

|

2014

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tom Nr 1

36--37

PL

W pracy przedstawiono symulację CFD powstawania kropli w pojedyn-czym dystrybutorze w kolumnie ekstrakcyjnej. Określono wpływ takich parametrów, jak średnica dystrybutora, temperatura oraz prędkość fazy w dystrybutorze na wielkość kropli, co pozwala na zaprojektowanie dystrybutora o optymalnym rozmiarze. Wyniki symulacji CFD mogą dać cenne informacje dotyczące tworzenia się kropli. Uzyskane wyniki symulacji zweryfikowano poprzez porównanie z wartościami obliczonymi z korelacji literaturowych.

EN

CFD simulation was used to investigate drop formation in a single hole of the distributor working in a solvent extraction column. Effect of various operating and design parameters on drop formation was investigated in order to optimize a distributor construction. Results indicated that CFD simulations could provide useful information on drop formation. Simulation results were verified by comparison to well-known correlation data.

3

Personal Ventilation Modeling Using a CFD Analysis

80%

Szczepanik-Ścisło N.

World Scientific News

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2016

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tom 57

298-307

EN

The growing trend for energy savings has resulted in tightening the building envelope, so the risk of contaminant accumulation and cross contamination is growing. Often, traditional mechanical ventilation systems that are installed in airtight buildings are not efficient in providing the proper amount of fresh air for individuals and do not protect them from cross contamination. Personal ventilation is an alternative to traditional ventilation systems as it provides fresh and purified air directly to the breathing zone. Not only does this method, in many cases, improve the thermal comfort of occupants, but also protects them from cross contamination from other occupants. In this study an air terminal device was tested to see if it would protect the occupant from cross contamination under changing conditions of the flow rate. Different velocities were simulated using the AnsysFluent CFD program, thanks to which the velocity around the occupants face was shown. The chosen velocities were 15 L/s, 10 L/s, 5L/s and 1L/s. The results showed that when the air flow was low, the personal ventilation system may not be effective in protecting against cross contamination.

4

Numerical investigation of particle separation in a centrifugal air separator

80%

Kaczyński J. , Kraft M.

Transactions of the Institute of Fluid-Flow Machinery

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2017

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tom nr 135

57--71

EN

This paper presents the modeling approaches and results of numerical investigations into particle separation in a production-scale industrial centrifugal air separator. The gaseous phase was modeled using an Eulerian formulation, while the particle phase was modeled using a Lagrangian particle tracking approach. Two-way coupling between continuous and disperse phase was included and turbulence modeled using the realizable k-ε model. The resulting comprehensive system model provides correct predictions of the power consumption and of pressure losses in the device over the full operation range, and proved ability of accurately predicting the size-dependent particle separation eﬃciencies down to nominal particle sizes of 2 µm.

5

Modeling of the Aeration System of a Sequencing Batch Reactor

80%

Zaburko J. , Głowienka R. , Widomski M. K. , Szulżyk-Cieplak J. , Babko R. , Łagód G.

Journal of Ecological Engineering

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2020

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tom Vol. 21, nr 7

249--256

EN

The use of modern methods as well as modeling and simulation tools in the design of bioreactors allows for the analysis of the flow phenomena in a short period of time without the need of physical model preparation, and thus for the optimization of existing solutions. The article presents the simulations of the aeration process in an SBR-type bioreactor, realized by means of computational fluid dynamics (CFD) and ANSYS 12.1 software. The subject of the analysis was a diffuser of own design. The Design Modeler 12.1 module was used for the preparation of geometry representing the analyzed design, and the discretization of the continuous domain was carried out with the ANSYS Meshing 12.1 tool. The ANSYS Fluent 6.3 solver was used For model calculations. On the basis of the results obtained from the conducted simulations, it is possible to predict the parameters which will increase efficiency and effectiveness without the need to build a real set of prototype models of aeration systems. The results obtained indicate that an increase in the aeration velocity results in a decrease in the minimum Y-axis velocity for both the mixture and air. The observed differences are caused by the shape of the geometric model and the velocity of the air outlet through the openings, which affects the hydraulic process in the chamber. These processes affect both the amount of oxygen dissolved in the bioreactor and the behavior of the suspension in volume. The turbulence intensity during the aeration process is concerned mainly in the range from 3.9 to 8.7% and is comparable with the average values of turbulence degree obtained by other researchers. The air bubble diameter ranged from 0.3 to 4.5 mm, in the case of aeration velocity 5.68 cm/s, a significant part of the chamber were air bubbles with a diameter of 2.6 to 3.9 mm, i.e. they were not the limit values.

6

Investigations of aerodynamics of Tesla bladeless microturbines

80%

Lampart P. , Jędrzejewski Ł.

Journal of Theoretical and Applied Mechanics

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2011

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tom Vol. 49 nr 2

477-499

EN

The paper presents an analysis of a Tesla bladeless turbine for a cogenerating micro-power plant of heat capacity 20 kW, which operates in an organic Rankine cycle with a low-boiling medium. Numerical calculations of the flow in several Tesla turbine models are performed for a range of design parameters. Results of the investigations exhibit interesting features in the distribution of flow parameters within the turbine interdisk space. The efficiency of the Tesla turbine depends on many parameters, including pressure, temperature and velocity conditions, rotational speed of the rotor as well as on the number, diameter, distance between the disks and the state of the disk surface and, finally, on the number and arrangement of the supply nozzles. The calculated flow efficiences of the investigated Tesla turbine models show that the best obtained solutions can be competitive as compared with classical small bladed turbines.

PL

W pracy przedstawiono analizę bezłopatkowej turbiny tarczowej Tesli pracującej w organicznym obiegu Rankine'a z czynnikiem niskowrzącym w mikrosiłowni kogene- racyjnej o mocy cieplnej 20 kW. Wykonano obliczenia numeryczne przepływu w turbinie Tesli w szerokim zakresie zmienności parametrów pracy turbiny. Wyniki badań obrazują szereg ciekawych cech w rozkładzie parametrów przepływu w przestrzeniach międzytarczowych turbiny. Sprawność turbiny Tesli zależy od wielu parametrów przepływowych, takich jak ciśnienie, temperatura, prędkość czynnika, prędkość obrotowa wirnika, oraz od wielu parametrów geometrycznych, m.in. od liczby i średnicy tarcz, odległości między tarczami, stanu powierzchni tarcz oraz układu dysz zasilających. Obliczone sprawności modeli turbiny Tesli wskazują, że najlepsze rozwiązania tej turbiny mogą konkurować z klasycznymi turbinami łopatkowymi.

7

The application of a jet fan for the control of air and methane streams mixing at the excavations cross - the results of numerical simulations

80%

Wrona P. , Różański Z. , Pach P. , Domagała L.

Management Systems in Production Engineering

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2016

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tom nr 3 (23)

156--162

EN

The paper presents the results of numerical simulations into the distribution of methane concentration at the intersection of two excavations with a fan (turned on) giving the air stream to the area of the crossing. Assumed case represents emergency situation related to the unexpected flow of methane from an excavation and its mixing with fresh air. It is possible when sudden gas outburst takes place, methane leaks from methane drainage system or gas leaks out the pipelines of underground coal gasification devices. Three options were considered – corresponding to three different speeds of the jet fan. They represent three stages of fan work. First – low air speed is forced by a pneumatic fan, when electricity is cut off after high methane concentration detection. Medium speed can be forced by pneumatic-electric device when methane concentration allows to turn on the electricity. Third, the highest speed is for electric fans. Simulations were carried out in the Fire Dynamics Simulator (FDS) belongs to the group of programs Computational Fluid Dynamics (CFD). The governing equations are being solved in a numerical way. It was shown that proposed solution allows partial dilution of methane in every variant of speed what should allow escape of the miners from hazardous area.

PL

W artykule przedstawiono wyniki symulacji komputerowych dotyczących zagadnienia rozkładu stężenia metanu przy skrzyżowaniu dwóch wyrobisk z włączonym wentylatorem kierunkującym strugę powietrza w rejon stropu skrzyżowania. Założona sytuacja dotyczyła awaryjnego wypływu metanu z zagazowanego wyrobiska do korytarza, którym płynie powietrze świeże. Taka sytuacja jest możliwa na przykład na skutek nagłego wyrzutu gazów, rozszczelnienia instalacji odmetanowania lub wycieku gazu z instalacji podziemnego zgazowania węgla. Rozpatrzono trzy warianty – odpowiadające trzem różnym prędkościom przepływu powietrza wywołanego pracą wentylatora pomocniczego. Pierwszy wariant dotyczy najmniejszej prędkości powietrza generowanej przez wentylator pneumatyczny, działający po odcięciu zasilania elektrycznego na skutek przekroczenia dozwolonego stężenia metanu. Drugi wariant to większą prędkość powietrza, generowana przez wentylator pneumatyczno-elektryczny. Trzeci wariant stanowi największą prędkość powietrza wytwarzaną przez wentylator elektryczny. Symulacje prowadzono w programie Fire Dynamics Simulator (FDS) należącym do grupy programów Computational Fluid Dynamics (CFD), rozwiązujących w swych algorytmach równania mechaniki płynów w sposób numeryczny. Wykazano, że zastosowanie proponowanego rozwiązania, umożliwi częściowe rozcieńczenie metanu w każdym z badanych wariantów, umożliwiając na przykład ucieczkę załogi z wyrobiska zagrożonego wybuchem.

8

PIV method as a means of optimization and validation of fluid flow in flue gas path

80%

Sulovcova K. , Papučík Š. , Patsch M. , Kapjor A. , Medvecký Š.

Structure and Environment

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2014

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tom Vol. 6, no. 3

41--44

EN

The production of flue gases and particulate matters also take part in combustion process. Solid particulate matters are dragged into the air with fumes and adversely affect the air quality, environment, human and animal health. Reducing of particulate matter emissions is very important not only for large particle sources but also for small sources that are involved in environmental pollution, too. Those small producers are for example small heat sources. In this paper reduction of particulate matter production in small heat source by modification of the flue gas path by using CFD simulation and PIV method is considered.

9

The analysis of distribution of the reaction mixture in ammonia oxidation reactor

80%

Moszkowski B. , Wajman T. , Sobczak K. , Inger M. , Wilk M.

Polish Journal of Chemical Technology

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2019

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tom Vol. 21, nr 1

9--12

EN

This article describes the influence of various design modifications of the ammonia oxidation reactor operating in nitric acid plant TKIV in Kędzierzyn-Koźle on flow distribution of an air-ammonia mixture. The CFD (Computational Fluid Dynamics) simulations of turbulent flow were carried out with SST k-ω turbulence model to close the system of RANS (Reynolds Averaged Navier-Stokes) equations. The simulation results show that the properly selected perforated plate screen and the conical diffuser ensure uniform flow of gas on the ammonia oxidation catalysts and on the catalysts for nitrous oxide decomposition. It was proved experimentally achieving uniform temperature of nitrous gases in different locations under the catalytic gauzes and high efficiency of ammonia oxidation and nitrous oxide decomposition.

10

Numerical Simulation of Emergency Release of Liquid Petroleum Gas on a Car Gas Station

80%

Salamonowicz Z. , Majder-Lopatka M. , Dmochowska A. , Piechota-Polanczyk A. , Polanczyk A.

Rocznik Ochrona Środowiska

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2021

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tom Tom 23

65--77

EN

LPG storage tanks may be seriously threatened by a fire coming from nearby fuels or by leakage appearance. The aim of the study was to prepare a three-dimensional model of LPG release on a car gas station under different environmental conditions. CFD simulations of liquid and gas phase release from a tank localized on a car gas station was performed. First, ALOHA software was applied to determine mass flow rate, while Ansys software was used to determine the shape and size of hazardous zone. To reflect real condition atmospheric stability classes were applied. It was observed that for classes A-D the hazardous zone was decreasing. While, for E and F class the range was increased. It was noticed that the location of the leakage affects the extent of the danger zone. For the leaking below the liquid surface analyzed LPG has liquid form. While, for the leaking above the liquid surface analyzed LPG has gas form. Furthermore, for liquid leakage the largest hazard zone of release was observed.

11

Application of Conjugate Simulation for Determination of Temperature and Stress Distributions During Curing Process of Pre-Impregnated Composite Fibers

80%

Golewski P. , Sadowski T.

Archives of Metallurgy and Materials

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2017

|

tom Vol. 62, iss. 4

2295--2301

EN

The composites made of continuous fibers in the form of unidirectional and fabric prepregs are widely used in many fields of engineering for the production of lightweight and durable parts or whole structures. To achieve this, we not only need to possess knowledge of the composite mechanics, but also have to master the technology. In most cases, particularly for parts with advanced geometric shapes, autoclaving technique is used. The success of the carried out process occurs when the prepreg reaches the proper temperature throughout its volume in the specified time, where there are no overheated or unheated zones as well as when the prepreg is correctly pressed against the mold. In order to ensure adequate stiffness, the mold has much greater thickness than formed composite and the stiffening ribs. The result is that the time required for prepreg heating is greatly extended. To prevent this, the appropriate electric heaters embedded in the silicone grips are used. The paper presents problems related to the mold structures and application of numerical methods aiming at early verification of the temperature and stress distribution. The coupled analysis of CFD (computational fluid dynamic) and heat transfer structural simulations were performed in Abaqus program. The studies were carried out for the airfoil fragment. A total of 12 simulations were conducted, 6 cases in which heat was supplied only from air flowing through the autoclave and 6 cases which included heaters inside the silicone grips. In the result the inhomogeneity of prepreg heating for each of the mold geometry was compared, and the average temperature was obtained after 60 seconds from the process initiation. Both the pressure inside the silicone grips (before inserting the mold into the autoclave) and the non-uniform temperature distribution result in the formation of stresses whose values were analyzed for molds made of aluminum. For this purpose the temperature dependent elastic – plastic material model was used for aluminum molds.

12

Determination of influence of internal surface roughness of a fan rotor onto its performance parameters

80%

Fortuna S.

Transactions of the Institute of Fluid-Flow Machinery

|

2014

|

tom nr 126

111--121

EN

Computional fluid dynamics study and experimental test using the standard methods on flow characteristics of the centrifugal fan, have been presented in this paper. This investigation was performed to determine the influence of internal surface roughness of fan rotor onto its performance parameters. The testing results are presented in form of graphs showing the efficiency, pressure and power in function of flow.

13

A numerical analysis of pollutant dispersion in street canyon: influence of the turbulent Schmidt number

70%

Abed B. , Bouarbi L. , Hamidou M. K. , Bouzit M.

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2017

|

tom Vol. 26, No. 4

423--436

EN

Realizing the growing importance and availability of motor vehicles, we observe that the main source of pollution in the street canyons comes from the dispersion of automobile engine exhaust gas. It represents a substantial effect on the micro-climate conditions in urban areas. Seven idealized-2D building configurations are investigated by numerical simulations. The turbulent Schmidt number is introduced in the pollutant transport equation in order the take into account the proportion between the rate of momentum turbulent transport and the mass turbulent transport by diffusion. In the present paper, we attempt to approach the experimental test results by adjusting the values of turbulent Schmidt number to its corresponding application. It was with interest that we established this link for achieving our objectives, since the numerical results agree well with the experimental ones. The CFD code ANSYS CFX, the k, e and the RNGk-e models of turbulence have been adopted for the resolutions. From the simulation results, the turbulent Schmidt number is a range of 0.1 to 1.3 that has some effect on the prediction of pollutant dispersion in the street canyons. In the case of a flat roof canyon configuration (case: runa000), appropriate turbulent Schmidt number of 0.6 is estimated using the k-epsilon model and of 0.5 using the RNG k-e model.

14

A Study of CFD Simulations of the Flow Pattern in an Agitated System with a Pitched Blade Worn Turbine

70%

Skočilas J. , Fořt I. , Jirout T.

Chemical and Process Engineering

|

2013

|

tom 34

|

nr 1

39-49

EN

This paper presents a numerical analysis of an agitated fully baffled cylindrical vessel with a down pumping four blade worn or unworn pitched blade impeller (α = 45° and 30°) under a turbulent flow regime. CFD simulations predict the pumping capacity of the system equipped by worn and unworn pitched blade impeller. Experimental data were taken from the authors’ previous work and compared with results of numerical computations. A good agreement with experimental data was obtained. The ensemble-average mean velocity field with worn and unworn impellers was computed. It follows from the simulation results that the wear rate of the impeller blade has a significantly negative effect on the velocity distribution in an agitated liquid. The greater the destruction of the worn blade, the higher is the deformation of the velocity field around the rotating impeller, with a simultaneous decrease in impeller pumping capacity.

15

Coupled finite volume and finite element method analysis of a complex large-span roof structure

60%

Szafran J. , Juszczyk K. , Kamiński M.

International Journal of Applied Mechanics and Engineering

|

2017

|

tom Vol. 22, no. 4

995--1017

EN

The main goal of this paper is to present coupled Computational Fluid Dynamics and structural analysis for the precise determination of wind impact on internal forces and deformations of structural elements of a longspan roof structure. The Finite Volume Method (FVM) serves for a solution of the fluid flow problem to model the air flow around the structure, whose results are applied in turn as the boundary tractions in the Finite Element Method problem structural solution for the linear elastostatics with small deformations. The first part is carried out with the use of ANSYS 15.0 computer system, whereas the FEM system Robot supports stress analysis in particular roof members. A comparison of the wind pressure distribution throughout the roof surface shows some differences with respect to that available in the engineering designing codes like Eurocode, which deserves separate further numerical studies. Coupling of these two separate numerical techniques appears to be promising in view of future computational models of stochastic nature in large scale structural systems due to the stochastic perturbation method.

16

Symulacja ruchu cieczy w zbiornikach przenośnych

60%

Domagała M.

Czasopismo Techniczne. Mechanika

|

2011

|

tom R. 108, z. 4-M/1

87-91

PL

W artykule przedstawiono symulację falowania cieczy znajdującej sie w zbiorniku podczas krótkotrwałego, wzdłużnego przyśpieszenia o wartości 2g. Symulacje przeprowadzono przy wykorzystaniu metod CFD w systemie Ansys CFX dla zbiornika bez przegród, jak i z różnymi konstrukcjami przegród. Przedstawiono wyniki symulacji w odpowiednich przedziałach czasowych, jak również wypadkową siłę wzdłużną działającą na zbiornik w zależności od rodzaju stosowanych przegród.

EN

This paper presents simulation of sloshing during short time longitudinal acceleration at mobile tank using CFD tools Ansys CFX. It was presented shape of free surface shape at various time steps as well as a resultant force acting on tank walls.

17

CFD modeling and rapid prototyping of liquid jet pump

60%

Momeni H. , Lisowski E.

Czasopismo Techniczne. Mechanika

|

2011

|

tom R. 108, z. 4-M/2

369-374

EN

This paper presents using Rapid Prototyping and CFD tools in modeling Liquid Jet Liquid pump. Prototype of LJL pump was made with FDM technology and was prepared to install measurement equipment and to perform experimental tests. Than results of test will be used to validate CFD model of LJL pump in order to design pump with required specification.

PL

W artykule przedstawiono metodę modelowania i projektowania pomp strumieniowych z wykorzystaniem narzędzi CFD oraz technologii szybkiego prototypowania. Wykonany w technologii FDM prototyp pompy przygotowano do zainstalowania aparatury pomiarowej i prowadzenia badań doświadczalnych.

18

Comparative analysis of assumptions for numerical simulation of the effects of fire - safety of evacuation from the building structure

60%

Dorsz A. , Rusowicz A. , Prawdzik A.

Inżynieria Bezpieczeństwa Obiektów Antropogenicznych

|

2020

|

tom Nr 4

1--15

EN

Ensuring a safe evacuation for the users of a building is a major goal when designing structures and systems protecting them against the effects of a fire. The article discusses the safety assessment for evacuation of users from a building exemplified by an analysis using computational fluid mechanics to reproduce the environmental conditions during a fire. It presents a way to evaluate the possibility of a safe evacuation of users from a facility by indicating the criteria for the assessment of conditions on the evacuation routes during emergency evacuation. In order to verify the criteria for assessing the evacuation safety, a three-dimensional model of the object under consideration has been prepared, for which a dedicated calculation solver of Fire Dynamic Simulator fluid mechanics has been used to recreate the fire conditions in the building. Prepared calculation model takes into account both the development of a fire on a given floor of the building and the simulation of the designed fire ventilation system in operation. In the paper the authors compare the assumptions used to create a calculation model and analyze their impact on the assessment of evacuation safety. Comparative analysis of the assumptions used to prepare the fire model allowed to draw conclusions particularly important for the people evaluating the evacuation safety on the basis of the analysis of the operation of fire ventilation systems using the computational fluids mechanics.

19

Analiza numeryczna CFD układów chłodzenia maszyn elektrycznych - weryfikacja doświadczalna. Cz. I

60%

Będkowski B. , Jarek T.

Maszyny Elektryczne : zeszyty problemowe

|

2013

|

tom Nr 1(98)

247-250

PL

W artykule przedstawiono analizę numeryczną CFD układu chłodzenia silnika z przewietrznikiem własnym. Zamodelowano w programie 3D układ chłodzenia maszyny o wzniosie 90 i przeprowadzono symulację numeryczną jego wydajności dla różnych prędkości obrotowych. Równocześnie wykonano badania laboratoryjne rzeczywistego modelu. Badania przeprowadzono dwoma metodami: za pomocą walca Thomasa (metoda kalorymetryczna) oraz przy użyciu termoanemometru. Na ich podstawie zweryfikowano możliwości analizy CFD maszyn chłodzonych za pomocą przewietrznika. W kolejnej części artykułu zostanie przedstawiona weryfikacja doświadczalna numerycznej analizy wodnego systemu chłodzenia.

EN

The numerical CFD analysis of the external fan cooling system of electrical motor is presented in the paper. The digital 3D model of the real air cooling system of electrical motor was designed. The cooling system's efficiency was calculated. Numerical computation for several rotational speeds were realized. At the same time the laboratory measurements of the real model of electrical motor were carried out. The measurements were conducted by two methods: by Thomas cylinder (calometric measurement principle) and by hotwire anemometer (average velocity principle). On the basis of experimental results the capabilities of CFD numerical analysis of electrical motor’s external fan cooling system were verified. The comparison of the thermal and flow experimental results of the water cooling system with the numerical analysis results will be shown in future publication.

20

Możliwości zastosowania numerycznej mechaniki płynów (CFD) do symulacji przepływu krwi przez tętnice wieńcowe. Przykłady segmentacji obrazów tomografii komputerowej i budowy modelu do obliczeń CFD

60%

Peryt-Stawiarska S. , Wasilewski J.

Inżynieria i Aparatura Chemiczna

|

2014

|

tom Nr 6

403--405

PL

W pracy przedstawiono wyniki symulacji numerycznych CFD przepływu krwi przez lewą i prawą tętnicę wieńcową. Symulacje wykonano w oparciu o segmentację obrazów angiograficznych uzyskanych za pomocą wielowarstwowej tomografii komputerowej. Otrzymane wyniki zostały przedstawione w postaci rozkładów wartości naprężeń ścinających na ściance WSS. Dane te jakościowo porównane z danymi literaturowymi. Stwierdzono, że metoda CFD z powodzeniem może być stosowana do symulacji przepływu krwi przez tętnice wieńcowe.

EN

CFD results of blood flow through the left and right coronary artery are presented in the paper. Simulations were performed based on geometry obtained through the segmentation of angiographic images using computer tomography. The results are shown in a form of wall shear stress (WSS) distribution. A qualitative comparison of simulation results with the data taken from literature was carried out. It was found that the CFD method can be successfully used to simulate the blood flow through the coronary arteries.