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1
Content available Pulsatile powell-eyring nanofluid flow in a channel with inclined magnetic field and chemical reaction
Srinivas Suripeddi, Challa Kalyan Kumar, Badeti Satyanarayana, Kumar P. Bharath
Engineering Transactions
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2023
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Vol. 71, iss. 4
519--535
EN
The current article addresses the impacts of the pulsatile flow of Powell-Eyring nanofluid using Buongiorno’s model in a horizontal channel. It also describes the combined impacts of thermophoresis and Brownian motion. Blood is an example of a Powell-Eyring fluid. The Runge-Kutta (R-K) 4th-order method, along with the shooting technique, is used to determine solutions for velocity, temperature, and concentration. The impacts of different parameters, including an inclined magnetic field, chemical reaction, Lewis number, and heat source or sink parameter, are illustrated graphically. The mass flux distribution decreases due to an increase in the values of the Powell-Eyring fluid parameter.
2
Content available remote Experimental study of a lock-in phenomenon in the case of a mechanical oscillator flowmeter
Szudarek Maciej, Turkowski Mateusz
Mechanik
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2020
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R. 93, nr 7
13--15
EN
Oscillatory flowmeters are susceptible to pulsatile flow and mechanical oscillator flowmeters are no exception. The experimental study was conducted to determine possible measurement errors for specific pulsation amplitude thresholds. The study verified that no frequency lock-in takes place for pulsation frequencies which are subharmonics of the natural oscillation frequency, nor for harmonics higher than the 2nd.
PL
Przepływomierze z oscylatorem mechanicznym – podobnie jak wszystkie przepływomierze oscylacyjne – są wrażliwe na pulsacje przepływu. Przeprowadzono badania eksperymentalne wpływu amplitudy pulsacji na błąd pomiarowy w zakresie występowania zjawiska unoszenia częstotliwości. Nie zaobserwowano natomiast wpływu pulsacji w przypadku częstotliwości będących podwielokrotnością częstotliwości oscylacji albo wielokrotnością wyższą niż druga.
3
Content available Investigation of blood flow rheology using second-grade viscoelastic model (Phan-Thien–Tanner) within carotid artery
Ramiar A., Larimi M. M., Ranjbar A. A.
Acta of Bioengineering and Biomechanics
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2017
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Vol. 19, no. 3
27--41
EN
Purpose: Hemodynamic factors, such as Wall Shear Stress (WSS), play a substantial role in arterial diseases. In the larger arteries, such as the carotid artery, interaction between the vessel wall and blood flow affects the distribution of hemodynamic factors. The fluid is considered to be non-Newtonian, whose flow is governed by the equation of a second-grade viscoelastic fluid and the effects of viscoelastic on blood flow in carotid artery is investigated. Methods: Pulsatile flow studies were carried out in a 3D model of carotid artery. The governing equations were solved using finite volume C++ based on open source code, OpenFOAM. To describe blood flow, conservation of mass and momentum, a constitutive relation of simplified Phan-Thien–Tanner (sPTT), and appropriate relations were used to explain shear thinning behavior. Results: The first recirculation was observed at t = 0.2 s, in deceleration phase. In the acceleration phase from t = 0.3 s to t = 0.5 s, vortex and recirculation sizes in bulb regions in both ECA and ICA gradually increased. As is observed in the line graphs based on extracted data from ICA, at t = 0.2 s, τyy is the maximum amount of wall shear stress and τxy the minimum one. The maximum shear stress occurred in the inner side of the main branch (inner side of ICA and ECA) because the velocity of blood flow in the inner side of the bulb region was maximum due to the created recirculation zone in the opposite side in this area. Conclusions: The rheology of blood flow and shear stress in various important parts (the area that are in higher rates of WSS such as bifurcation region and the regions after bulb areas in both branches, Line1–4 in Fig. 7) were also analyzed. The investigation of velocity stream line, velocity profile and shear stress in various sections of carotid artery showed that the maximum shear stress occurred in acceleration phase and in the bifurcation region between ECA and ICA which is due to velocity gradients and changes in thinning behavior of blood and increasing strain rate in Newtonian stress part.
4
Content available remote A study on a newly designed aortofemoral prosthetic Y graft
Fujimoto T., Nakano S., Iwamura H., Shiraishi Y., Yambe T., Umezu M.
Biocybernetics and Biomedical Engineering
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2008
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Vol. 28, no. 1
59-63
EN
Aortofemoral prosthetic Y grafts are applied for treating abdominal aortic aneurysms. In this study, experiments were conducted in order to demonstrate the effects of an incremental increase in branch diameter in a newly designed aortofemoral Y graft under conditions of both steady and pulsatile flow conditions. It was revealed that in Y grafts, the incremental increase by only 4 mm in the branch diameter affects hydrodynamic characteristics drastically under conditions of both steady and pulsatile flow conditions.
5
Content available remote On pulsatile hydromagnetic flow of an oldroyd fluid with heat transfer
Srinivas S., Malathy T., Sachdev P. L.
Engineering Transactions
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2007
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Vol. 55, iss. 1
79-94
EN
The problem of heat transfer to pulsatile flow of hydromagnetic viscoelastic fluid has been studied. Expressions for the velocity, temperature distribution and mass flow rate are obtained. The rate of heat transfer at the plates has also been calculated. These expressions are evaluated numerically for various values of the parameters. The influence of pertinent parameters on temperature, heat transfer coefficient and mass flux has been studied and numerical results obtained are presented graphically.
6
The behaviour of the mechanical oscillator flowmeters under pulsating flow conditions
Turkowski M.
Elektronika : konstrukcje, technologie, zastosowania
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2004
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Vol. 45, nr 8-9
254-256
EN
The influence of the flow rate pulsation on the characteristics of the mechanical oscillator flowmeters has been investigated. The phenomenon of the frequency "lock-in", well known from the vortex flowmeters, also occurs in the mechanical oscillator flow-meter. The results of the investgation showed that in the presence of pulsation the mechanical oscillator flowmeter can give false readings and the error can achieve the value of 27% at pulsation amplitude of 13%.
PL
Przedstawiono wyniki badań wpływu pulsacji na wskazania przepływomierzy z oscylatorem mechanicznym. Zjawisko unoszenia częstotliwości, znane z przepływomierzy wirowych, występuje także w przypadku przepływomierzy z oscylatorem mechanicznym. Z badań wynika, że w obecności pulsacji błędy przepływomierza mogą osiągnąć wartość do 27% przy amplitudzie pulsacji równej 13%.
7
Content available remote Pulsatile flow of electrically conducting non-Newtonian fluid and heat transfer through porous medium in a circular pipe
Eldabe N. T. M., Ghaly A. Y., El-hassan M., Oaf M. E.
Mechanics and Mechanical Engineering
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2001
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Vol. 5, nr 1
5-20
EN
The influence of elasticity and magnetic field on pulastile viscoelastic flow and heat transfer in a circular pipe is examined. By means of the perturbation method of the velocity and temperature fields, the analytical solution of the velocity and temperature are obtained in terms of Bessel and hypergeometric functions .The discharge and the rate of heat transfer are determined through the course of discussions.
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