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Wyświetlanie 1-15 z 33
Tytuł:
Survey of applications of discrete vortex method in civil engineering
Autorzy:
Nowicki, T.
Powiązania:
https://bibliotekanauki.pl/articles/390713.pdf
Data publikacji:
2009
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
discrete vortex method
Navier-Stokes equation
Opis:
This paper includes an introduction to Discrete Vortex Method (DVM) and its comparison with other methods of computer fluid dynamics. In its second part it focuses on the most important applications of DVM from the civil engineering point of view. Some examples known form literature are presented theoretical as well as experimental.
Źródło:
Budownictwo i Architektura; 2009, 5, 2; 29-38
1899-0665
Pojawia się w:
Budownictwo i Architektura
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Rationality of solving 3D circulation problems exclusively with the use of the Navier-Stokes equation (Reynolds equation)
Autorzy:
Koronowicz, T.
Powiązania:
https://bibliotekanauki.pl/articles/1986684.pdf
Data publikacji:
2002
Wydawca:
Politechnika Gdańska
Tematy:
3D circulation problems
vortex theory
Navier-Stokes equation
Opis:
The paper presents problems connected with solving 3D circulation problems. The existence of vortex singularities in the flow behind a body is a characteristic feature of such problems. The vortices influence the velocity and pressure fields in the vicinity of a body. A proposition of rational merging the methods based on the N-S equation together with vortex methods (based on the vorticity equation) is discussed. Such a connection enables accurate and efficient determination of vortex singularities in the flow behind a body.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 1; 217-224
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical simulation of 3D viscous turbomachinery flow with high-resolution ENO scheme and modern turbulence model
Autorzy:
Yershov, S. V.
Rusanov, A. V.
Powiązania:
https://bibliotekanauki.pl/articles/1967653.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
CFD
computational fluid dynamics CFD
turbomachinery
Navier-Stokes equation
turbulence
Opis:
This paper presents the basic principles of construction of numerical models for 3D viscous turbulent flows through multi stage turbomachines. The great attention is given to such properties of the methods as accuracy, linear and non-linear stability, robustness and computational efficiency. It is shown that these properties can be guaranteed if the implicit Godunov’s type ENO scheme is used. A 3D code FLOWER has been developed within this concept. Using the code the numerical results are obtained for flows through high loaded compressor cascades, a turbine stage, a low-pressure multi stage turbine and a centrifugal compressor stage. The results of optimisation of a low-pressure turbine last stage are presented.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 4; 459-476
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Heuristic derivation of Brinkmans seepage equation
Autorzy:
Wojnar, R.
Powiązania:
https://bibliotekanauki.pl/articles/297997.pdf
Data publikacji:
2017
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie
Tematy:
porosity
Darcy’s law
Stokes’ equation
successive iterations
Born’s approximation
Opis:
Brinkman’s law is describing the seepage of viscous fluid through a porous medium and is more acurate than the classical Darcy’s law. Namely, Brinkman’s law permits to conform the flow through a porous medium to the free Stokes’ flow. However, Brinkman’s law, similarly as Schro¨dinger’s equation was only devined. Fluid in its motion through a porous solid is interacting at every point with the walls of pores, but the interactions of the fluid particles inside pores are different than the interactions at the walls, and are described by Stokes’ equation. Here, we arrive at Brinkman’s law from Stokes’ flow equation making use of successive iterations, in type of Born’s approximation method, and using Darcy’s law as a zero-th approximation.
Źródło:
Technical Sciences / University of Warmia and Mazury in Olsztyn; 2017, 20(4); 359-374
1505-4675
2083-4527
Pojawia się w:
Technical Sciences / University of Warmia and Mazury in Olsztyn
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Laminar flow past the bottom with obstacles - a porous medium approximation
Autorzy:
Bielski, Włodzimierz
Wojnar, Ryszard
Powiązania:
https://bibliotekanauki.pl/articles/2104770.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
plants
permeability
gravity-driven flow
Darcy-Brinkman’s law
Stokes equation
Opis:
We provide a model of a stationary laminar flow in a channel at the bottom of which plants grow in a dense layer. Since this layer of plants is dense, we treat it as a porous medium and we propose to describe the flow in such a medium by Brinkman’s equation. The flow in the fluid layer located above (infiltrated by water) the layers of plants is described by the Stokes equation. We show that such a model gives results consistent with experimental observations. We indicate also that this new model complements the previously given model in which the benthonic plants were considered as a suspension, so the previous model referred to the channel at the bottom of which the plants grew rare. For high permeability of the porous medium, we arrive at the results obtained for the medium filled with a liquid with a suspension.
Źródło:
Journal of Theoretical and Applied Mechanics; 2022, 60, 3; 509--520
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fast algorithms for calculations of viscous incompressible flows using the Velocity Correction Method
Autorzy:
Kosma, Z.
Motyl, Przemysław
Powiązania:
https://bibliotekanauki.pl/articles/1943235.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska
Tematy:
Navier-Stokes equation
artificial compressibility
method of lines
two grids method
Opis:
An artificial compressibility method is designed to simulate stationary two-and threedimensional motions of a viscous incompressible fluid. A standard method of lines approach is applied in this contribution. A partial differential equation system is discretized in space by secondorder finite-difference schemes on uniform computational grids, and the time-variable is preserved as continuous. Initial value problems for systems of ordinary differential equations for pressure and velocity components are computed using the Galerkin-Runge-Kutta method of third order. Some test calculations for laminar flows in square, cubic, triangular and semicircular cavities with one uniform moving wall and double bent channels are reported.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2008, 12, 3-4; 289-301
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fast algorithms for calculations of viscous incompressible flows using the artificial compressibility method
Autorzy:
Kosma, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1943234.pdf
Data publikacji:
2008
Wydawca:
Politechnika Gdańska
Tematy:
Navier-Stokes equation
velocity correction method
method of lines
two grids method
Opis:
The velocity correction method is designed to simulate stationary and non-stationary, two- and three-dimensional motions of a viscous incompressible fluid. The basic assumption of this method consists in splitting the velocity and the pressure fields and calculations are performed in two steps. In the first step, a tentative velocity field is determined by simplified equations for momentum conservation. In the second step the Neumann problem for the Poisson equations is solved to obtain the computational pressure, and the velocity components are corrected. A standard method of lines approach and the two grids method are applied in this contribution. Some test calculations for laminar and transitional flows in square and cubic cavities with one moving wall as well as in a backward-facing step are reported.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2008, 12, 3-4; 273-287
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calculation of viscous incompressible flow around an aerofoil using a modified velocity correction method
Autorzy:
Kosma, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1965150.pdf
Data publikacji:
2005
Wydawca:
Politechnika Gdańska
Tematy:
Navier-Stokes equation
incompressible viscous flows
velocity correction method
flows over aerofoils
Opis:
The two-dimensional unsteady motion of viscous incompressible fluid around an aerofoil at a large angle of attack has been computed. A modified velocity correction method splitting the velocity field has been designed to solve this problem. First, a tentative velocity field is determined from the equations of momentum conservation for explicit gradients of computational pressure. Then, the Neumann problem for the Poisson equation is solved to estimate the computational pressure, and velocity components are corrected. Test calculations have been made for the case of flow around the NACA 0012 aerofoil with an incidence of 34 degrees. The domain outside the aerofoil was transformed into a canonical one using conformal mapping. Computations were made on 100×100 and 100×200 grids for Reynolds numbers of Re=400, 600 and 1000. Comparison with numerical and experimental data reported in the literature has shown that the method is suitable for simulating 2D external viscous flows.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2005, 9, 1; 37-52
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oil pressure distribution in variable height gaps
Rozklady cisnienia oleju w szczelinach plaskich o zmiennej wysokosci
Autorzy:
Zloto, T.
Kowalski, K.
Powiązania:
https://bibliotekanauki.pl/articles/792863.pdf
Data publikacji:
2011
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
variable height gap
pressure distribution
hydraulic oil
hydraulic machine
Navier-Stokes equation
Źródło:
Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2011, 11C
1641-7739
Pojawia się w:
Teka Komisji Motoryzacji i Energetyki Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Flow behavior in weakly permeable micro-tube with varying viscosity near the wall
Autorzy:
Gupta, R. R.
Kumar, V.
Chand, S.
Powiązania:
https://bibliotekanauki.pl/articles/779656.pdf
Data publikacji:
2017
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
hollow-fiber
micro-tube
permeation
algorithm
variable viscosity
velocity profile
equation of motion
navier-stokes equation
Opis:
Weakly permeable micro-tubes are employed in many applications involving heat and/or mass transfer. During these processes, either solute concentration builds up (mass transfer) or steep change in temperature (heat transfer) takes place near the permeable wall causing a change in the viscosity of the fluid. Results of the present work suggest that such change in viscosity leads to a considerable alteration in the flow behavior, and the commonly assumed parabolic velocity profile no longer exists. To solve the problem numerically, the equation of motion was simplified to represent permeation of incompressible, Newtonian fluid with changing viscosity through a micro-tube. Even after considerable simplification, the accuracy of the results was the same as that obtained by previously reported results for some specific cases using rigorous formulation. The algorithm developed in the present work is found to be numerically robust and simple so that it can be easily integrated with other simulations.
Źródło:
Polish Journal of Chemical Technology; 2017, 19, 4; 16-21
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oil leaks intensity in variable-height gaps
Natężenie przepływu przecieków oleju w szczelinach o zmiennej wysokości
Autorzy:
Zloto, T.
Kowalski, K.
Powiązania:
https://bibliotekanauki.pl/articles/792722.pdf
Data publikacji:
2013
Wydawca:
Komisja Motoryzacji i Energetyki Rolnictwa
Tematy:
variable height gap
hydraulic machine
Navier-Stokes equation
hydraulic oil
oil leakage
flow intensity
Źródło:
Teka Komisji Motoryzacji i Energetyki Rolnictwa; 2013, 13, 2
1641-7739
Pojawia się w:
Teka Komisji Motoryzacji i Energetyki Rolnictwa
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A comparative study on translational diffusion coefficient for some mammalian serum albumins
Porównanie współczynnika dyfuzji translacyjnej dla albumin surowicy kilku ssaków
Autorzy:
Monkos, Karol
Powiązania:
https://bibliotekanauki.pl/articles/1039603.pdf
Data publikacji:
2010
Wydawca:
Śląski Uniwersytet Medyczny w Katowicach
Tematy:
viscosity
stokes-einstein equation
serum albumin
translational diffusion coefficient
Opis:
BACKGROUND The aim of the present paper is investigation of the volume fraction dependence of the translational diffusion coefficient for some mammalian serum albumins in aqueous solutions. MATERIAL AND METHODS The viscosity of bovine, equine, ovine and rabbit serum albumin aqueous solutions was measured at temperatures ranging from 5oC to 45oC and in a wide range of concentrations. The measurements were performed with an Ubbelohde-type capillary microviscometer. RESULTS Translational diffusion coefficient at infinitely dilute solutions Do(T) can be calculated from generalized Stokes-Einstein equation if the hydrodynamic radius of albumin is known. It gives Do(T) in the range from 3.5×10-11 m2 /s (at 5oC) to 10.2 10-11 m2 /s (at 45oC) for bovine serum albumin, from 3.59×10-11 m2 /s (at 5oC) to 10.4 10-11 m2 /s (at 45oC) for equine serum albumin, from 3.42×10-11 m2 /s (at 5oC) to 9.92×10-11 m2 /s (at 45oC) for ovine serum albumin, and from 3.36×10-11 m2 /s (at 5oC) to 9.74×10-11 m2 /s (at 45oC) for rabbit serum albumin. Translational diffusion coefficient for higher concentrations D(T,φ) can be obtained from the relation: D(T,φ) = Do(T)Ηo(T)/Η(T,φ), where φ denotes volume fraction and Ηo(T) and Η(T,φ) are viscosities of water and solution, respectively, at temperature T. CONCLUSIONS The obtained results show that the translational diffusion coefficient decreases linearly with increasing volume fraction, when φ does not exceed the value of about 0.1. The dependence of the translational diffusion coefficient on volume fraction in a broader range of φ, i.e. from dilute to concentrated solutions, is nonlinear and can be described by a stretched exponential function.
WSTĘP Celem niniejszej pracy jest zbadanie zależności współczynnika dyfuzji translacyjnej od ułamka objętościowego dla albumin surowicy kilku ssaków w roztworach wodnych. MATERIAŁ I METODY Lepkość wodnych roztworów albuminy surowicy wołowej, końskiej, owczej i króliczej zmierzono w zakresie temperatur od 5oC do 45oC i w szerokim zakresie stężeń. Pomiary wykonano przy pomocy kapilarnego mikrowiskozymetru typu Ubbelohde’a. WYNIKI Współczynnik dyfuzji translacyjnej dla roztworów rozcieńczonych Do(T) można obliczyć z uogólnionego równania Stokesa-Einsteina, jeżeli znany jest promień hydrodynamiczny albuminy. Daje to Do(T) w zakresie od 3.5×10-11 m2 /s (w 5oC) do 10.2×10-11 m2 /s (w 45oC) dla albuminy surowicy wołowej, od 3.59×10-11 m2 /s (w 5oC) do 10.4×10-11 m2 /s (w 45oC) dla albuminy surowicy końskiej, od 3.42×10-11 m2 /s (w 5oC) do 9.92×10-11 m2 /s (w 45oC) dla albuminy surowicy owczej i od 3.36×10-11 m2 /s (w 5oC) do 9.74×10-11 m2 /s (w 45oC) dla albuminy surowicy króliczej. Współczynnik dyfuzji translacyjnej dla wyższych stężeń D(T,φ) można otrzymać z relacji: D(T,φ) = Do(T)Ηo(T)/Η(T,φ), w której φ oznacza ułamek objętościowy a Ηo(T) i Η(T,φ) są, odpowiednio, lepkością wody i roztworu w temperaturze T. WNIOSKI Otrzymane wyniki pokazują, że współczynnik dyfuzji translacyjnej maleje liniowo wraz ze wzrostem ułamka objętościowego, jeżeli φ nie przekracza wartości około 0.1. Zależność współczynnika dyfuzji translacyjnej od ułamka objętościowego w szerszym zakresie φ , tzn. dla roztworów od rozcieńczonych do stężonych, jest nieliniowa i można ją opisać rozciągniętą funkcją wykładniczą.
Źródło:
Annales Academiae Medicae Silesiensis; 2010, 64, 5-6; 43-53
1734-025X
Pojawia się w:
Annales Academiae Medicae Silesiensis
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The well-posedness of a swimming model in the 3-D incompressible fluid governed by the nonstationary Stokes equation
Autorzy:
Khapalov, A.
Powiązania:
https://bibliotekanauki.pl/articles/330536.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
swimming model
coupled PDE/ODE system
nonstationary Stokes equation
sprzężony system PDE/ODE
równanie Stokesa
Opis:
We introduce and investigate the well-posedness of a model describing the self-propelled motion of a small abstract swimmer in the 3-D incompressible fluid governed by the nonstationary Stokes equation, typically associated with low Reynolds numbers. It is assumed that the swimmer’s body consists of finitely many subsequently connected parts, identified with the fluid they occupy, linked by rotational and elastic Hooke forces. Models like this are of interest in biological and engineering applications dealing with the study and design of propulsion systems in fluids.
Źródło:
International Journal of Applied Mathematics and Computer Science; 2013, 23, 2; 277-290
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Addendum to “The well-posedness of a swimming model in the 3-D incompressible fluid governed by the nonstationary Stokes equation”
Autorzy:
Khapalov, A.
Powiązania:
https://bibliotekanauki.pl/articles/330456.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
swimming model
coupled PDE/ODE system
nonstationary Stokes equation
sprzężony system PDE/ODE
równanie Stokesa
Opis:
In this addendum we address some unintentional omission in the description of the swimming model in our recent paper (Khapalov, 2013).
Źródło:
International Journal of Applied Mathematics and Computer Science; 2013, 23, 4; 905-906
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Numerical investigation of flow in mixed-flow pump with volute
Autorzy:
Sedlar, M.
Powiązania:
https://bibliotekanauki.pl/articles/1967635.pdf
Data publikacji:
2001
Wydawca:
Politechnika Gdańska
Tematy:
CFD
computational fluid dynamics CFD
flow separation
cavitation
Navier-Stokes equation
unsteady phenomena
mixed-flow pump
volute
Opis:
The work considers the modelling of flow in a complete mixed-flow pump with volute, including tip leakage flows, using both quasi-steady and true transient models of rotor/stator interaction. The CFX-TASCflow CFD package from AEA Technology is applied to calculate flows for a wide range of flow rates from about 0.2 to 1.4 Q/sub 0pt/. Fairly detailed flow structures have been predicted based on the flow rates, especially impeller inlet recirculation and separation on the suction side of the blades for suboptimal rates of flow, as well as strong secondary flows and separation in the volute for off-design conditions. The rotor/stator interaction influence on flow phenomena both in the impeller and volute have been investigated with very interesting results, providing good insight into the dynamics of flow close to the volute tongue. Based on the computational results, pump performance curves (Q-H, Q- eta /sub h/ and Q-P, eta /sub h/ being the hydraulic efficiency) have been obtained. The data from this numerical investigation have been used to improve the inlet part of the impeller blades, especially close to the tip. The geometry modifications have resulted in reduced cavitation in the impeller as well as noise at suboptimal rates of flow.
Źródło:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2001, 5, 4; 595-602
1428-6394
Pojawia się w:
TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 33

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