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1

Comparative analysis of numerical simulations of blood flow through the segment of an artery in the presence of stenosis

Shaikh Fozia, Shaikh Asif Ali, Hincal Evren, Qureshi Sania

Journal of Applied Mathematics and Computational Mechanics

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2023

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Vol. 22, nr 2

49--61

EN

A mathematical model is developed to study the characteristics of blood flowing through an arterial segment in the presence of a single and a couple of stenoses. The governing equations accompanied by an appropriate choice of initial and boundary conditions are solved numerically by Taylor Galerkin’s time-stepping equation, and the numerical stability is checked. The pressure, velocity, and stream functions have been solved by Cholesky’s method. Furthermore, an in-depth study of the flow pattern reveals the separation of Reynolds number for the 30 and 50% blockage of single stenosis and 30% blockage of multi-stenosis. The present results predict the excess pressure drop across the stenosis site than it does for the inlet of the artery with single and multiple stenosis and the increase in the velocity is observed at the center of the artery.

2

The calculation of stress intensity factor steel of railway wheels

Vakulenko Igor, Proydak Svetlana, Askerov Hangardas

Zeszyty Naukowe. Transport / Politechnika Śląska

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2020

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z. 109

187--193

EN

From an analysis of the dependence complex of carbon steel properties on structural parameters, it was found that for an isostructural state, the influence of austenite grain size on impact strength exceeds the dependence on carbon content. As a result of explaining correlation relationships between individual mechanical characteristics, to evaluate critical stress intensity factor, a relationship is proposed based on the use of impact strength. The proportionality coefficient in proposed dependence is determined by ratio of elongation to narrowing at tensile test.

3

Zwężenia w szczelinach wentylacyjnych

Patoka Krzysztof

Materiały Budowlane

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2019

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nr 2

28--29

4

Analiza funkcjonowania zwężenia na drodze krajowej

Gondek S., Ostrowski K.

Logistyka

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2015

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nr 3

1524--1533, CD 1

PL

Właściwe projektowanie programu sygnalizacji świetlej na zwężonych odcinkach dróg krajowych z ruchem wahadłowym wymaga stosowania wielu parametrów odpowiednich dla takich obiektów. Należy do nich natężenia nasycenia. Krajowe przepisy nie podają miarodajnych wartości. W referacie przestawiono wyniki badań empirycznych na zwężonym odcinku drogi krajowej sterowanym stałoczasową sygnalizacją świetlną. Przeprowadzone badania miały na celu analizęzachowań kierujących na zwężeniu oraz oszacowaniewartości i zmienności natężeń nasycenia.Uzyskane wartości porównano z wartościami przyjętymi w projekcie ruchowymi i wykazano istotne różnice.

EN

Proper design of traffic signals program on narrowed sections of roads requires a number of parameters which are appropriate for such facilities. One of them is saturation flow. National rules do not provide authoritative values. The paper presents empirical research carried out on the tapered section of a national road with traffic signals. This research aimed to analyze the behavior of drivers on the taper and to estimate the value and variability of saturation flow. Obtained values were compared with the values adopted during the design stage and significant differences have been outlined.

5

Simulation of steady laminar blood flow through arterial stenosis using computational fluid dynamics

Banerjee M. K., Ganguly R., Datta A.

International Journal of Applied Mechanics and Engineering

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2009

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Vol. 14, no 1

91-111

EN

The flow of blood through a rigid artery with different degrees of stenosis has been studied. Two different shapes (rectangular and cosine) of stenosis are considered while blood is modeled either as a Newtonian or non-Newtonian fluid. Three different degrees of stenosis, expressed in percentage, are considered representing mild to severe stenoses. The flow separates from the arterial wall at the stenosis and reattaches at a point downstream, forming a recirculating eddy. The pressure drop over the length of the artery varies for the different cases indicating the impact on the heart. A peak in the wall shear stress is observed at the location of the stenosis and zero stress points are observed where the flow separates and reattaches the wall. Results show marked differences in the flow pattern and shear stress between Newtonian and non-Newtonian models. Moreover, the power-law model exhibits a different trend as compared to the Casson model in predicting the flow field and wall shear stress.

6

FE analysis of tube forming process with experimental verification

Mandic V., Stefanovic M., Zivkovic M., Grujovic N., Misic B.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 18, nr 1-2

303--306

EN

Purpose: of this paper: The paper presents some results of extensive investigation of steel seam-welded tubes forming process, by applying combined treatment of material narrowing and expansion. The objective of executed numerical FE and experimental investigations was to determine the optimal technology for production of tubular product at simple tools and at the standard forming processing machines, without defects and with demanded dimensional accuracy. Design/methodology/approach: Tube forming was done in one phase, in tool with two shaping spherical parts, that enables the expansion of the specimen’s central zone and the filling of the die due to narrowing of the specimen ends, when certain conditions are achieved and with appropriate combination of influential process parameters (outer diameter, height and tube’s wall thickness, as well as friction conditions). Series of physical and numerical FE experiments was performed. Findings: Optimal dimensions of tubular product, with required process stability, were obtained this way. Also, results of experiments pointed out that the best process stability and die filling is achieved with specimens whose surfaces had previously been chemically treated. Results of numerical FE simulations of process are quite verified by experiments. Practical implications: Obtained results have practical significance in solving similar processing problems. It also enables to investigate and broaden the knowledge on stability of these kinds of processes, beyond the scope of experimental investigations. Tubular product that is subjected to numerical-experimental investigation in this paper is prepared by narrowing it at both ends thus excluding the possibility to apply holder inside the tube. Originality/value: Proposed method offers possibility for production of tubular products at simple forming machines and tools, without complex and expensive hydroforming equipment.