Wave Dispersion Analysis of Pulsating Flows in a Circular Conduit Using a Lumped Parameter Model

2015 ◽  
Author(s):  
Sejong Chun ◽  
Jonghan Jin
Keyword(s):  
Blood Flow ◽  
Pressure Gradient ◽  
Wave Dispersion ◽  
Dispersion Analysis ◽  
Experimental Results ◽  
Lumped Parameter Model ◽  
Lumped Parameter ◽  
Flow Simulator

Wave dispersion is a key element in understanding the pulsating flows in a circular rigid pipe. This study suggests that an extended Taylor’s frozen field hypothesis should make the lumped parameter model be more practical because pressure instead of pressure gradient can be measured with simpler instrumentation. Lumped parameter model as well as wave dispersion is introduced, and then some experimental results with a blood flow simulator were analyzed to validate its idea.

scholarly journals A Distributed Lumped Parameter Model of Blood Flow

2020 ◽  
Vol 48 (12) ◽  
pp. 2870-2886
Author(s):  
Mehran Mirramezani ◽  
Shawn C. Shadden
Keyword(s):  
Blood Flow ◽  
Lumped Parameter Model ◽  
Lumped Parameter

Dynamics of cerebral blood flow regulation explained using a lumped parameter model

2002 ◽  
Vol 282 (2) ◽  
pp. R611-R622 ◽  
Author(s):  
Mette S. Olufsen ◽  
Ali Nadim ◽  
Lewis A. Lipsitz
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Cardiovascular Response ◽  
Lumped Parameter Model ◽  
Initial Increase ◽  
Windkessel Model ◽  
Cerebrovascular Resistance ◽  
Posture Change ◽  
Lumped Parameter ◽  
Young Subjects

The dynamic cerebral blood flow response to sudden hypotension during posture change is poorly understood. To better understand the cardiovascular response to hypotension, we used a windkessel model with two resistors and a capacitor to reproduce beat-to-beat changes in middle cerebral artery blood flow velocity (transcranial Doppler measurements) in response to arterial pressure changes measured in the finger (Finapres). The resistors represent lumped systemic and peripheral resistances in the cerebral vasculature, whereas the capacitor represents a lumped systemic compliance. Ten healthy young subjects were studied during posture change from sitting to standing. Dynamic variations of the peripheral and systemic resistances were extracted from the data on a beat-to-beat basis. The model shows an initial increase, followed approximately 10 s later by a decline in cerebrovascular resistance. The model also suggests that the initial increase in cerebrovascular resistance can explain the widening of the cerebral blood flow pulse observed in young subjects. This biphasic change in cerebrovascular resistance is consistent with an initial vasoconstriction, followed by cerebral autoregulatory vasodilation.

Numerical investigation of multiphase blood flow coupled with lumped parameter model of outflow

2019 ◽  
Vol 30 (1) ◽  
pp. 228-244
Author(s):  
Bartlomiej Melka ◽  
Wojciech P. Adamczyk ◽  
Marek Rojczyk ◽  
Marcin L. Nowak ◽  
Maria Gracka ◽  
...  
Keyword(s):  
Blood Flow ◽  
Lumped Parameter Model ◽  
Coarctation Of Aorta ◽  
Multiphase Model ◽  
Computational Domain ◽  
Windkessel Model ◽  
Content Type ◽  
Model Based ◽  
Lumped Parameter ◽  
Euler Approach

Purpose The purpose of this paper is the application of the computational fluid dynamics model simulating the blood flow within the aorta of an eight-year-old patient with Coarctation of Aorta. Design/methodology/approach The numerical model, based on commercial code ANSYS Fluent, was built using the multifluid Euler–Euler approach with the interaction between the phases described by the kinetic theory of granular flow (KTGF). Findings A model of the blood flow in the arches of the main aorta branches has been presented. The model was built using the multifluid Euler–Euler approach with the interaction between the phases described by the KTGF. The flow and pressure patterns, as well as the volumetric concentration of the blood components, were calculated. The lumped parameter model was implemented to couple the interaction of the computational domain with the remaining portion of the vascular bed. Originality/value The multiphase model based on the Euler–Euler approach describing blood flow in the branched large vessel with a three-element Windkessel model in the coarcted geometry was not previously described in the literature.

Analysis and Experimental Estimation of Nonlinear Dispersion in a Periodic String

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Kevin L. Manktelow ◽  
Michael J. Leamy ◽  
Massimo Ruzzene
Keyword(s):  
Dispersion Curve ◽  
Wave Dispersion ◽  
Lumped Parameter Model ◽  
Nonlinear Frequency ◽  
Nonlinear Dispersion ◽  
Frequency Shifts ◽  
Wave Transport ◽  
Lumped Parameter ◽  
Dispersion Frequency ◽  
Nonlinear Frequency Response

Wave dispersion in a string carrying periodically distributed masses is investigated analytically and experimentally. The effect of the string's geometric nonlinearity on its wave propagation characteristics is analyzed through a lumped parameter model yielding coupled Duffing oscillators. Dispersion frequency shifts are predicted that correspond to the hardening behavior of the nonlinear chain and that relate well to the backbone of individual Duffing oscillators. Experiments conducted on a string of finite length illustrate the relation between measured resonances and the dispersion properties of the medium. Specifically, the locus of resonance peaks in the frequency/wavenumber domain outlines the dispersion curve and highlights the existence of a frequency bandgap. Moreover, amplitude-dependent resonance shifts induced by the string nonlinearity confirm the hardening characteristics of the dispersion curve. Analytical and experimental results provide a critical link between nonlinear dispersion frequency shifts and the backbone curves intrinsic to nonlinear frequency response functions. Moreover, the study confirms that amplitude-dependent wave properties for nonlinear periodic systems may be exploited for tunability of wave transport characteristics such as frequency bandgaps and wave speeds.

A lumped parameter model of cerebral blood flow control combining cerebral autoregulation and neurovascular coupling

2012 ◽  
Vol 303 (9) ◽  
pp. H1143-H1153 ◽  
Author(s):  
Bart Spronck ◽  
Esther G. H. J. Martens ◽  
Erik D. Gommer ◽  
Frans N. van de Vosse
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Flow Control ◽  
Cerebral Autoregulation ◽  
Neurovascular Coupling ◽  
Flow Regulation ◽  
Lumped Parameter Model ◽  
Blood Flow Regulation ◽  
Lumped Parameter ◽  
Blood Flow Control

Cerebral blood flow regulation is based on a variety of different mechanisms, of which the relative regulatory role remains largely unknown. The cerebral regulatory system expresses two regulatory properties: cerebral autoregulation and neurovascular coupling. Since partly the same mechanisms play a role in cerebral autoregulation and neurovascular coupling, this study aimed to develop a physiologically based mathematical model of cerebral blood flow regulation combining these properties. A lumped parameter model of the P2 segment of the posterior cerebral artery and its distal vessels was constructed. Blood flow regulation is exerted at the arteriolar level by vascular smooth muscle and implements myogenic, shear stress based, neurogenic, and metabolic mechanisms. In eight healthy subjects, cerebral autoregulation and neurovascular coupling were challenged by squat-stand maneuvers and visual stimulation using a checkerboard pattern, respectively. Cerebral blood flow velocity was measured using transcranial Doppler, whereas blood pressure was measured by finger volume clamping. In seven subjects, the model proposed fits autoregulation and neurovascular coupling measurement data well. Myogenic regulation is found to dominate the autoregulatory response. Neurogenic regulation, although only implemented as a first-order mechanism, describes neurovascular coupling responses to a great extent. It is concluded that our single, integrated model of cerebral blood flow control may be used to identify the main mechanisms affecting cerebral blood flow regulation in individual subjects.

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