Numerical Simulation of Mass Transfer in Pulsatile Flow of Blood Characterized by Carreau Model under Stenotic Condition
01 Jan 2020-Journal of Applied Fluid Mechanics (Isfahan University of Technology)-Vol. 14, Iss: 3, pp 805-817
About: This article is published in Journal of Applied Fluid Mechanics.The article was published on 2020-01-01 and is currently open access. It has received 4 citations till now. The article focuses on the topics: Carreau fluid & Pulsatile flow.
01 Jan 1995
TL;DR: In this article, heat and mass transfer in the recirculation region of a pipe under steady and pulsatile conditions were studied under uniform and parabolic entrance velocity profiles and the results demonstrate the complexity of separation flows and identify characteristic regions of high and low heat/mass transfer.
Abstract: Abstract Heat and mass transfer phenomena were studied in the sudden expansion region of a pipe under steady and pulsatile conditions. The Prandtl number was varied from 100 to 12 000 and the flow was characterized for both uniform and parabolic entrance velocity profiles. A uniform velocity profile was used for pulsatile flow. It was found that heat transfer in the recirculation region was maximal near the area where wall shear was minimal. Blunting of the inlet profile caused the point of maximum heat transfer to move upstream. There was a nonlinear effect of Prandtl number on heat transfer which plateaued for Pr > 10 3 . The wall shear rate in the separation zone varied markedly with pulsatile flows, but the wall heat transfer remained relatively constant. The time-averaged pulsatile heat transfer at the wall was approximately the same as with steady flow with the mean Reynolds number. However, the isotherms within the pulsatile flow were markedly different from steady flow. The results demonstrate the complexity of separation flows and identify characteristic regions of high and low heat/mass transfer for high Prandtl/Schmidt pulsatile flow.
TL;DR: In this paper , a mathematical model is presented to analyze the double diffusive transport of hybrid nanofluids in microchannel, which is driven by cilia beating and electroosmosis in the presence of radiation effects and activation energy.
Abstract: Abstract A mathematical model is presented to analyze the double diffusive transport of hybrid nanofluids in microchannel. The hybrid nanofluids flow is driven by the cilia beating and electroosmosis in the presence of radiation effects and activation energy. Cu–CuO/blood hybrid nanofluids are considered for this analysis. Phase difference in the beatings of mimetic cilia arrays emerge symmetry breaking pump walls to control the fluid stream. Analytical solutions for the governing equations are derived under the assumptions of Debye–Hückel linearization, lubrication, and Rosseland approximation. Dimensional analysis has also been considered for applying the suitable approximations. Entropy analysis is also performed to examine the heat transfer irreversibility and Bejan number. Moreover, trapping phenomena are discussed based on the contour plots of the stream function. From the results, it is noted that an escalation in fluid velocity occurs with the rise in slippage effects near the wall surface. Entropy inside the pump can be eased with the provision of activation energy input or by the consideration of the radiated fluid in the presence of electroosmosis. The results of the present study can be applicable to develop the emerging thermofluidic systems which can further be utilized for the heat and mass transfer at micro level.
TL;DR: In this article , the influence of pulsatile flow on the oscillatory motion of an incompressible conducting boundary layer mucus fluid flowing through porous media in a channel with elastic walls is investigated.
Abstract: The influence of pulsatile flow on the oscillatory motion of an incompressible conducting boundary layer mucus fluid flowing through porous media in a channel with elastic walls is investigated. The oscillatory flow is treated as a cyclical time-dependent flux. The Laplace transform method using the Womersley number is used to solve non-linear equations controlling the motion through porous media under the influence of an electromagnetic field. The theoretical pulsatile flow of two liquid phase concurrent fluid streams, one kinematic and the other viscoelastic, is investigated in this study. To extend the model for various physiological fluids, we postulate that the viscoelastic fluid has several distinct periods. We also apply our analytical findings to mucus and airflow in the airways, identifying the wavelength that increases dynamic mucus permeability. The microorganism’s thickness, velocity, energy, molecular diffusion, skin friction, Nusselt number, Sherwood number, and Hartmann number are evaluated. Discussion is also supplied in various sections to investigate the mucosal flow process.
TL;DR: This work is useful for researchers to deeply understand the hemodynamic characteristics of curved arteries and there is important clinical significance to analyze the pathogenesis of cardiovascular disease considering microcirculation function and its coupling effect.
Abstract: BACKGROUND Microcirculation plays a key role in regulating blood flow but is not considered in previous research of hemodynamics. OBJECTIVE A curved artery model is established to study its hemodynamic characteristics based on microcirculation boundary. METHODS The hemodynamic model of a curved artery is constructed and simulated by computational fluid dynamics. The curved artery model is simulated by fluid-structure interaction. At the same time, a porous medium is used to simulate microcirculation as the outlet boundary. RESULTS The distribution characteristics of the blood flow velocity, the pressure and the wall shear stress in different sections at different time of the cardiac cycle are obtained. The results show that the velocities in curved arteries decrease and the pressures gradually increase. The blood flow velocity waveform and value are affected and they are sensitive to the microcirculation boundary. However, the pressure value is only affected by the microcirculation function. CONCLUSIONS This work is useful for researchers to deeply understand the hemodynamic characteristics of curved arteries. There is important clinical significance to analyze the pathogenesis of cardiovascular disease considering microcirculation function and its coupling effect.
TL;DR: In this paper, the authors present a Gebrauch bestimmt ausschließlich für den persönlichen, nicht kommerziellen Gebrauchs, which is a rechtschutzbestimmter gebrauch, and gilt vorbehaltlich der folgenden Einschränkungen.
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TL;DR: These studies confirm earlier findings under steady flow conditions that plaques tend to form in areas of low, rather than high, shear stress, but indicate in addition that marked oscillations in the direction of wall shear may enhance atherogenesis.
Abstract: Fluid velocities were measured by laser Doppler velocimetry under conditions of pulsatile flow in a scale model of the human carotid bifurcation. Flow velocity and wall shear stress at five axial and four circumferential positions were compared with intimal plaque thickness at corresponding locations in carotid bifurcations obtained from cadavers. Velocities and wall shear stresses during diastole were similar to those found previously under steady flow conditions, but these quantities oscillated in both magnitude and direction during the systolic phase. At the inner wall of the internal carotid sinus, in the region of the flow divider, wall shear stress was highest (systole = 41 dynes/cm2, diastole = 10 dynes/cm2, mean = 17 dynes/cm2) and remained unidirectional during systole. Intimal thickening in this location was minimal. At the outer wall of the carotid sinus where intimal plaques were thickest, mean shear stress was low (-0.5 dynes/cm2) but the instantaneous shear stress oscillated between -7 and +4 dynes/cm2. Along the side walls of the sinus, intimal plaque thickness was greater than in the region of the flow divider and circumferential oscillations of shear stress were prominent. With all 20 axial and circumferential measurement locations considered, strong correlations were found between intimal thickness and the reciprocal of maximum shear stress (r = 0.90, p less than 0.0005) or the reciprocal of mean shear stress (r = 0.82, p less than 0.001). An index which takes into account oscillations of wall shear also correlated strongly with intimal thickness (r = 0.82, p less than 0.001). When only the inner wall and outer wall positions were taken into account, correlations of lesion thickness with the inverse of maximum wall shear and mean wall shear were 0.94 (p less than 0.001) and 0.95 (p less than 0.001), respectively, and with the oscillatory shear index, 0.93 (p less than 0.001). These studies confirm earlier findings under steady flow conditions that plaques tend to form in areas of low, rather than high, shear stress, but indicate in addition that marked oscillations in the direction of wall shear may enhance atherogenesis.
TL;DR: This controversy was concerned with whether coronary artery thrombi were or were not directly responsible for all three clinical pictures of acute ischaemia.
Abstract: The clinical management of acute myocardial infarction and crescendo angina as well as the prevention of sudden ischaemic death require accurate knowledge of the underlying arterial pathology. It is on just this aspect that until recently there has been disagreement particularly among pathologists. In brief, this controversy was concerned with whether coronary artery thrombi were or were not directly responsible for all three clinical pictures of acute ischaemia. Resolution of the controversy has been derived from coronary angiography in life in patients with acute infarction and crescendo angina and from detailed pathological studies. These latter studies differ from many carried out previously by the use of postmortem coronary angiography and histological reconstruction of the microanatomy of occlusive lesions.
01 Jun 1974
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