Temat: pressure gradient - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Alcohol ablation of the interventricular septum in a patient with hypertrophic obstructive cardiomyopathy complicated by an increase in the pressure gradient in the left ventricular outflow tract : a case report
Ablacja alkoholowa przegrody międzykomorowej u chorej z kardiomiopatią przerostową zawężającą powikłana zwiększeniem gradientu ciśnień w drodze odpływu lewej komory
Autorzy:: Płazak, Wojciech
Gackowski, Andrzej
Kapelak, Bogusław
Odrowąż-Pieniążek, Piotr
Podolec, Piotr
Tracz, Wiesława
Sadowski, Jerzy
Krochin, Marek
Opis:: A case of a 70 year old female with hypertrophic obstructive cardiomyopathy who underwent alcohol ablation of the interventricular septum, is presented. Following the procedure, the pressure gradient decreased from 120 mmHg to 80 mmHg. However, 30 minutes after ablation the patients developed hypotension and pulmonary oedema. Echocardiography revealed a significant systolic anterior movement of the anterior leaflet of the mitral valve and elevated pressure gradient up to 200 mmHg. The patient underwent urgent surgery (myectomy), followed by the mitral valve replacement with a favourable outcome.
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 2.

Tytuł:: LES of converging-diverging channel flow with separation
Autorzy:: Kuban, L.
Elsner, W.
Tyliszczak, A.
Tematy:: LES
turbulent boundary layer
separation
channel flow
pressure gradient; Pokaż więcej
Wydawca:: Politechnika Gdańska
Powiązania:: https://bibliotekanauki.pl/articles/1943209.pdf Link otwiera się w nowym oknie
Opis:: The paper presents the results of LES simulation of two different turbulent channels with inlet conditions corresponding to the Reynolds number Re =395. In both cases a varying pressure gradient was obtained by an adequate curvature of one of the walls. The first case is treated as a benchmark and is used to validate the numerical procedure. This case is characterized by the same cross-section area at the inlet and outlet and a bump of a smooth profile located on one of the walls designed to be identical to the one used in the experiment conducted at Laboratorie de Mecanique de Lille (LML) (Marquillie et al., 2008). The second case corresponds to the geometry which reproduces the real geometry of the turbomachinery test section of the Czestochowa University of Technology. The test section was created in such a way as to produce the pressure gradient which would correspond to the conditions present in the axial compressor blade channel. The shape of both channels produced initially favorable (FPG) and then adverse pressure gradients (APG), and in this way created conditions for boundary layer separation. Due to a reverse flow where the turbulence transport is dictated by the dynamics of the large-scale eddies such a case is well suited to demonstrate predictive features of the LES technique.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Numerical analysis on the influence of the twisted blade on the aerodynamic performance of turbine
Autorzy:: Jin, J.
Wang, Z.
Cao, L.
Tematy:: turbine
twisted blade
leakage vortex
pressure gradient
tip clearance; Pokaż więcej
Wydawca:: Politechnika Gdańska. Wydział Inżynierii Mechanicznej i Okrętownictwa
Powiązania:: https://bibliotekanauki.pl/articles/258444.pdf Link otwiera się w nowym oknie
Opis:: With the gradual increase of the thermal power unit capacity, the inlet steam parameters and flow of the turbine also increase gradually, which causes considerable secondary flow loss. Therefore, studying the causes and distribution of secondary flow loss within the level is of great significance to effectively improve the stage internal efficiency of turbine. Take high-pressure stage moving blade of a turbine as the research object, and adopt the k-ωSST model, the SIMPLEC algorithm to numerically simulate the formation and development process of leakage vortex between the tip clearance of the positive bending twisted blade and its effect on the secondary flow of cascade passage. Results show that relative to the conventional twisted blade, the scope of influence of leakage vortex which the steam flow formed near the suction surface of positive bending twisted blade and the disturbance to passage mainstream become smaller, and the increase of tip clearance has weakened the „C” type pressure gradient of suction surface of the positive bending twisted blade, increased the thickness of the boundary layer at both ends of blades and the loss of the blade end.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Parametric sensitivity of a CFD model concerning the hydrodynamics of trickle-bed reactor (TBR)
Autorzy:: Janecki, D.
Burghardt, A.
Bartelmus, G.
Tematy:: hydrodynamics
trickle-flow regime
pressure gradient
liquid holdup
phases interaction
CFD
hydrodynamika
gradient ciśnienia; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Czasopisma i Monografie PAN
Powiązania:: https://bibliotekanauki.pl/articles/184944.pdf Link otwiera się w nowym oknie
Opis:: The aim of the present study was to investigate the sensitivity of a multiphase Eulerian CFD model with respect to relations defining drag forces between phases. The mean relative error as well as standard deviation of experimental and computed values of pressure gradient and average liquid holdup were used as validation criteria of the model. Comparative basis for simulations was our own data-base obtained in experiments carried out in a TBR operating at a co-current downward gas and liquid flow. Estimated errors showed that the classical equations of Attou et al. (1999) defining the friction factors Fjk approximate experimental values of hydrodynamic parameters with the best agreement. Taking this into account one can recommend to apply chosen equations in the momentum balances of TBR.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Application of the diagnostic plot in estimation of the skin friction in turbulent boundary layer under an adverse pressure gradient
Autorzy:: Niegodajew, P.
Dróżdż, A.
Elsner, W.
Tematy:: turbulent boundary layer
friction velocity
Clauser-chart
adverse pressure gradient
diagnostic plot; Pokaż więcej
Wydawca:: Instytut Podstawowych Problemów Techniki PAN
Powiązania:: https://bibliotekanauki.pl/articles/38622693.pdf Link otwiera się w nowym oknie
Opis:: The paper concerns the problem of determining friction velocity in wallbounded flows affected by an adverse pressure gradient (APG). In the work of Niegodajew et al. [22] the corrected Clauser chart method (CCCM) for such flow conditions was proposed. This approach utilises the mean velocity profiles and turbulence intensity profiles to accurately estimate the friction velocity. In another work, Drózdz et al. [27] presented a modified version of the diagnostic-plot scaling (DPS) which allows for direct reconstruction of turbulence intensity profiles based on the local mean velocity profile, even when the flow is affected by a strong pressure gradient. This paper is aimed at verifying whether, when combining both of these methods (i.e. DPS and CCCM), the friction velocity can be accurately determined for APG flow conditions and one can possibly take advantage from both methods. The analysis revealed that the new approach is able to predict the friction velocity with uncertainty less than 5% for all the considered cases for the Clauser–Rotta parameter β < 17. Lastly, DPS-CCCM was also confronted with two empirical approaches (from available literature) allowing for estimation of the friction velocity under APG conditions. The performance of DPS-CCCM was found to be better than the ones of two other empirical approaches.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: A multi-proxy approach to detect the pore pressure and the origin of overpressure in sedimentary basins : an example from the Gulf of Suez rift basin
Autorzy:: Radwan, Ahmed Eid Ahmed
Dostawca treści:: Repozytorium Uniwersytetu Jagiellońskiego

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Skocz do pozycji: 7.

Tytuł:: Optimizing the process of mixing diesel fuel and biofuel in a blade mixer to improve mixture quality
Optymalizacja procesu mieszania oleju napędowego i biopaliwa w mieszalniku łopatkowym w celu poprawy jakości mieszanki
Autorzy:: Burlaka, Serhii
Kupchuk, Ihor
Boretska, Tetiana
Gontaruk, Yaroslav
Melnyk, Maryna
Tematy:: mixer geometry
numerical solution
turbulence
pressure gradient
turbulent flows
geometria mieszalnika
rozwiązanie numeryczne
turbulencja
gradient ciśnienia
przepływy turbulentne; Pokaż więcej
Wydawca:: Polska Akademia Nauk. Instytut Gospodarki Surowcami Mineralnymi i Energią PAN
Powiązania:: https://bibliotekanauki.pl/articles/59112488.pdf Link otwiera się w nowym oknie
Opis:: This research examines an important aspect of technological processes – the process of mixing diesel fuel and biofuel in a specially designed paddle mixer. The main goal is to optimize and improve the quality of the resulting mixture. The use of the FlowVision CFD (Computational Fluid Dynamics) program in this study is of great importance and helps to achieve significant results in the study and optimization of the diesel-biofuel mixing process. In the context of many industrial and technological processes, where efficient mixing of liquids plays an important role, turbulent mixing is of great importance. Optimal mixing not only improves the quality of products, but also ensures the unity of complex reactions and also helps to reduce the time of completion of the process. It is important to emphasize that the research focuses not only on the quantitative aspects of mixing but also on the study of the influence of the geometry of the mixer on the turbulent characteristics of the flow. This can lead to the development of new mixer designs aimed at maximizing the efficiency of the fuel mixing process, which, in turn, will help save resources and reduce emissions of harmful substances into the atmosphere. This research opens up prospects for further developments in the field of fuel blending technologies, which can lead to real improvements in production and sustainability. The discovery of new methods of optimal mixing of liquids in specially designed mixers can determine the future of energy efficiency and reduce the negative impact on the environment.
W niniejszym artykule analizowany jest ważny aspekt procesów technologicznych – proces mieszania oleju napędowego i biopaliwa w specjalnie zaprojektowanym mieszalniku łopatkowym. Głównym celem jest optymalizacja i poprawa jakości powstałej mieszanki. Wykorzystanie w badaniu programu FlowVision CFD (Computational Fluid Dynamics) ma ogromne znaczenie i pozwala na osiągnięcie znaczących wyników w analizie i optymalizacji procesu mieszania oleju napędowego z biopaliwem. W kontekście wielu procesów przemysłowych i technologicznych, gdzie ważną rolę odgrywa sprawne mieszanie cieczy, duże znaczenie ma mieszanie turbulentne. Optymalne mieszanie nie tylko poprawia jakość produktów, ale także zapewnia jednolitość złożonych reakcji, a także pomaga skrócić czas zakończenia procesu. Należy podkreślić, że badania skupiają się nie tylko na ilościowych aspektach mieszania, ale także na analizie wpływu geometrii mieszadła na turbulentną charakterystykę przepływu. Może to doprowadzić do opracowania nowych konstrukcji mieszadeł mających na celu maksymalizację efektywności procesu mieszania paliw, co w efekcie pozwoli zaoszczędzić zasoby i zmniejszyć emisję szkodliwych substancji do atmosfery. Badania te otwierają perspektywy dalszego rozwoju w dziedzinie technologii mieszania paliw, co może prowadzić do realnej poprawy produkcji i zrównoważonego rozwoju. Odkrycie nowych metod optymalnego mieszania cieczy w specjalnie zaprojektowanych mieszadłach może przesądzić o przyszłości efektywności energetycznej i ograniczeniu negatywnego wpływu na środowisko.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: On streamwise structures in boundary layer under adverse pressure gradient on inclined plate
Autorzy:: Uruba, V.
Prochazka, P.
Skala, V.
Tematy:: boundary layer
adverse pressure gradient
inclined plate
proper orthogonal decomposition
POD
oscillation pattern decomposition
OPD; Pokaż więcej
Wydawca:: Politechnika Gdańska
Powiązania:: https://bibliotekanauki.pl/articles/1955271.pdf Link otwiera się w nowym oknie
Opis:: The presented study is focused on experimental investigation of a boundary layer on a flat plate in an adverse pressure gradient. The flat plate is placed in a regular flow, the pressure gradient is generated by the plate inclination. The preceding studies deal with the structure of the wake behind the plate, the presented study concentrates on the flow structureclose to the suction surface of the plate. The dynamical behavior of the flow structures is studied in details with respect to the topology in the streamwise direction. In spite of the fact that thetime-mean flow field is close to 2D, more or less constant along the span, the instantaneous structures topology is fully 3D. Rather oblique structures are detected instead of those oriented in the streamwise direction. The patterns are travelling in the streamwise direction along the plate.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Transient flow through a porous channel with ramped pressure gradient and velocity slip boundary condition
Autorzy:: Jha, Basant K.
Yunus, Zainab Sa'id
Tematy:: przepływ przejściowy
prędkość
ciśnienie
transient flow
velocity slip
ramped pressure gradient
Riemann-Sum approximation technique; Pokaż więcej
Wydawca:: Uniwersytet Zielonogórski. Oficyna Wydawnicza
Powiązania:: https://bibliotekanauki.pl/articles/2174168.pdf Link otwiera się w nowym oknie
Opis:: A transient flow formation of an incompressible fluid through a horizontal porous channel assuming a ramped pressure gradient is considered with the velocity slip boundary conditions. The flow is a laminar flow caused by ramped pressure gradient along the flow direction. The equation governing the flow is modeled, and solved by the Laplace transformation technique to obtain a semi-analytical solution under slip boundary conditions. It was noted that the flow velocity increases as the slip parameter is increased.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Mathematical Model of Oxygen Transport in Cornea
Autorzy:: Avtar, Ram
Seth, Deepti
Kumar, Aadesh
Tematy:: Crank-Nicoloson method
Michaelis-Menten kinetics
Oxygentransport
Thomas algorithm
finite difference
metabolism
oxygen consumption
pressure gradient; Pokaż więcej
Wydawca:: Przedsiębiorstwo Wydawnictw Naukowych Darwin / Scientific Publishing House DARWIN
Powiązania:: https://bibliotekanauki.pl/articles/1159714.pdf Link otwiera się w nowym oknie
Opis:: The aim of present work is the development of a quasi-steady state model for the time course concentration profile describing the oxygen diffusion and consumption in a multilayered corneal tissue and investigation of the effect of various model parameters on the oxygen concentration for open and closed eyes. A simple mathematical model for the oxygen transport in multilayered corneal tissue was developed using Fick’s law of diffusion, Michaelis-Menten kinetics of metabolism. A Crank-Nicolson finite difference scheme of the equation describing the oxygen diffusion and consumption was written, in which spatial diffusive terms of the equation were approximated by central differences while the temporal terms were approximated by average of forward and backward time differences. A system of linear equations obtained from the Crank-Nicholson finite differences schemes was solved by the Thomas Algorithm in which successive improve approximate results are obtained.
Dostawca treści:: Biblioteka Nauki

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