scholarly journals Pumping Patterns and Work Done During Peristalsis in Finite-Length Elastic Tubes

2021 ◽  
Author(s):  
Shashank Acharya ◽  
Wenjun Kou ◽  
Sourav Halder ◽  
Dustin A. Carlson ◽  
Peter J. Kahrilas ◽  
...  
Keyword(s):  
Physiological State ◽  
Balloon Dilation ◽  
Elastic Tube ◽  
Peristaltic Wave ◽  
Immersed Boundary ◽  
Healthy Human ◽  
Elastic Tubes ◽  
Peristaltic Pumping ◽  
1D Model ◽  
Work Done

Abstract Balloon dilation catheters are often used to quantify the physiological state of peristaltic activity in tubular organs and comment on their ability to propel fluid which is important for healthy human function. To fully understand this system's behavior, we analyzed the effect of a solitary peristaltic wave on a fluid-filled elastic tube with closed ends. A reduced order model that predicts the resulting tube wall deformations, flow velocities and pressure variations is presented. This simplified model is compared with detailed fluid-structure 3D immersed boundary simulations of peristaltic pumping in tube walls made of hyperelastic material. The major dynamics observed in the 3D simulations were also displayed by our 1D model under laminar flow conditions. Using the 1D model, several pumping regimes were investigated and presented in the form of a regime map that summarizes the system's response for a range of physiological conditions. Finally, the amount of workdone during a peristaltic event in this configuration was defined and quantified. The variation of elastic energy and work done during pumping was found to have a unique signature for each regime. An extension of the 1D model is applied to enhance patient data collected by the device and find the work done for a typical esophageal peristaltic wave. This detailed characterization of the system's behavior aids in better interpreting the clinical data obtained from dilation catheters. Additionally, the pumping capacity of the esophagus can be quantified for comparative studies between disease groups.

Interactions of Nonlinear Waves in Fluid-Filled Elastic Tubes

2007 ◽  
Vol 62 (1-2) ◽  
pp. 21-28
Author(s):  
Hilmi Demiray
Keyword(s):  
Solitary Waves ◽  
Nonlinear Waves ◽  
Elastic Tube ◽  
Wave Number ◽  
Inviscid Fluid ◽  
Leading Order ◽  
Elastic Tubes ◽  
Longwave Approximation ◽  
Thin Walled ◽  
Analytical Phase

In this work, treating an artery as a prestressed thin-walled elastic tube and the blood as an inviscid fluid, the interactions of two nonlinear waves propagating in opposite directions are studied in the longwave approximation by use of the extended PLK (Poincaré-Lighthill-Kuo) perturbation method. The results show that up to O(k3), where k is the wave number, the head-on collision of two solitary waves is elastic and the solitary waves preserve their original properties after the interaction. The leading-order analytical phase shifts and the trajectories of two solitons after the collision are derived explicitly.

Large-amplitude unsteady flow in liquid-filled elastic tubes

1967 ◽  
Vol 29 (3) ◽  
pp. 513-538 ◽  
Author(s):  
John H. Olsen ◽  
Ascher H. Shapiro
Keyword(s):  
Water Waves ◽  
Large Amplitude ◽  
Linear Equations ◽  
Perturbation Expansion ◽  
Elastic Tube ◽  
Fluid Viscosity ◽  
Elastic Tubes ◽  
Non Linear ◽  
Laminar And Turbulent Flow ◽  
Large Amplitude Motion

Unsteady, large-amplitude motion of a viscous liquid in a long elastic tube is investigated theoretically and experimentally, in the context of physiological problems of blood flow in the larger arteries. Based on the assumptions of long wavelength and longitudinal tethering, a quasi-one-dimensional model is adopted, in which the tube wall moves only radially, and in which only longitudinal pressure gradients and fluid accelerations are important. The effects of fluid viscosity are treated for both laminar and turbulent flow. The governing non-linear equations are solved analytically in closed form by a perturbation expansion in the amplitude parameter, and, for comparison, by numerical integration of the characteristic curves. The two types of solution are compared with each other and with experimental data. Non-linear effects due to large amplitude motion are found to be not as large as those found in similar problems in gasdynamics and water waves.

Pressure Characteristics of the Esophagus and Its Sphincters in Dogs

1958 ◽  
Vol 193 (1) ◽  
pp. 9-14 ◽  
Author(s):  
Jerry F. Schlegel ◽  
Charles F. Code
Keyword(s):  
Gastroesophageal Junction ◽  
Elevated Pressure ◽  
Gastric Fundus ◽  
Peristaltic Wave ◽  
Human Beings ◽  
Healthy Human ◽  
Pressure Transducers ◽  
Small Water ◽  
Healthy Dogs ◽  
The Mean

The pressure in the esophagus and its sphincters in seven well-trained, intact, healthy dogs was studied using three small water-filled polyethylene tubes attached to pressure transducers. To obtain resting pressures these tubes were withdrawn at intervals of 0.5–2.0 cm through the gastroesophageal junction, the esophagus and the pharyngoesophageal junction. Swallowing was induced by injection of water into the mouth or pharynx of the animals, and responses were recorded from selected sites. At rest, bands of elevated pressure about 2 cm wide were detected at the pharyngoesophageal and gastroesophageal junctions. The mean maximal pressures in the two zones were 20 and 6.9 cm of water, respectively. Pressure in the esophagus at rest was less than that in the gastric fundus. When swallowing began, the elevated pressure in the junctional zones decreased promptly, rose to high values as the peristaltic wave of deglutition swept into them, and then declined to resting levels. A peristaltic wave of high pressure swept through the esophagus with each swallow. These findings indicate that the junctional zones act as sphincters. Their behavior is identical to that in healthy human beings. The pressure pattern in the esophagus itself with swallowing is also the same in the two species, but in the dog the peristaltic wave moves faster and the rise of pressure is briefer. These differences may reflect the fact that the muscle of the dog's esophagus is entirely skeletal.

Bubble transitions in strongly collapsed elastic tubes

2009 ◽  
Vol 633 ◽  
pp. 485-507 ◽  
Author(s):  
ALEXANDRA HEAP ◽  
ANNE JUEL
Keyword(s):  
Elastic Tube ◽  
Lung Damage ◽  
Air Bubbles ◽  
Critical Height ◽  
Opposite Wall ◽  
Elastic Tubes ◽  
Elastic Instabilities ◽  
Surface Tension Forces ◽  
Extensive Deformation ◽  
Selection Of

The selection of long air bubbles propagating steadily in a strongly collapsed fluid-filled elastic tube is investigated experimentally in a benchtop model of airway reopening. Localized regions of strong collapse are likely in the lung, because collapsing fluid-elastic instabilities promote extensive deformation of the airway cross-section beyond the point of opposite wall contact. We find that radical changes in the reopening mechanics occur at this point. We build on the recent identification by Heap & Juel (Phys. Fluids, vol. 20, 2008, article no. 081702) of three different steadily propagating bubbles (asymmetric, double-tipped and pointed) that are selected successively for increasing values of the capillary number (Ca, ratio of viscous to surface tension forces) in tubes initially collapsed beyond the point of opposite wall contact. The asymmetric bubble is also observed in less collapsed tubes for small values of Ca, and we show that it bifurcates super-critically from the usual parabolic-tipped bubble as Ca increases. We also characterize the mechanisms underlying the discontinuous transitions between asymmetric and double-tipped bubbles, and double-tipped and pointed bubbles. In particular, we find that the tube must reopen to a critical height for double-tipped bubbles to be selected. The length of the precursor fingers in the double-tipped bubble decreases with Ca, and the bubble loses stability to pointed bubbles when this length is less than the height of the tube at the point where the fingers merge. By contrast with the asymmetric and double-tipped bubbles, the pointed bubble infiltrates the most collapsed part of the tube to yield the rapid reopening of the airway at low pressure, with the potential to reduce ventilation-induced lung damage.

scholarly journals The influence of the resilience of the arterial wall on blood-pressure and on the pulse curve

1913 ◽  
Vol 86 (586) ◽  
pp. 180-186 ◽  
Keyword(s):  
Blood Pressure ◽  
Arterial Wall ◽  
Elastic Tube ◽  
Elastic Tubes

This communication is the result of two independent but converging lines of research. It is well known that when a fluid is driven with a rhythmically varying pressure through a sufficient length of a distensile elastic tube, the pressure at the exit loses its rhythm and becomes constant and the flow continuous, whereas if the tube is rigid, the pressure at the outlet varies as that at the inlet (less the change due to friction) and the outflow is intermittent. Since the arteries are distensile elastic tubes and the blood is rhythmically forced into them by the heart, it follows that the curve of blood-pressure must be altered to a greater or lesser degree by the distensibility and elasticity of the arterial wall.

scholarly journals Exhaled aerosol increases with COVID-19 infection, and risk factors of disease symptom severity

2020 ◽  
Author(s):  
David A. Edwards ◽  
Dennis Ausiello ◽  
Robert Langer ◽  
Jonathan Salzman ◽  
Tom Devlin ◽  
...  
Keyword(s):  
Surface Composition ◽  
Human Subjects ◽  
Physiological State ◽  
Human Study ◽  
Exhaled Breath ◽  
Healthy Human ◽  
Observational Cohort ◽  
Airway Mucus ◽  
Respiratory Droplets ◽  
Infection Study

ABSTRACTCoronavirus disease-19 (COVID-19) transmits by droplets generated from surfaces of airway mucus during processes of respiration within hosts infected by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) virus. We studied respiratory droplet generation and exhalation in human and nonhuman primate subjects with and without COVID-19 infection to explore whether SARS-CoV-2 infection, and other changes in physiological state, translates into observable evolution of numbers and sizes of exhaled respiratory droplets in healthy and diseased subjects. In our observational cohort study of the exhaled breath particles of 74 healthy human subjects, and in our experimental infection study of eight nonhuman primates infected by aerosol with SARS-CoV-2, we found that exhaled aerosol particles increase one to three orders of magnitude with aging, high BMI, and COVID-19 infection. These variances appear to be related to changes in airway mucus surface composition and the propensity for mucus surfaces to breakup into small droplets during acts of breathing. We also observed that 20% of those participating in our human study accounted for 80% of the overall exhaled bioaerosol, reflecting a bioaerosol distribution analogous to a classical 20:80 super spreader distribution.

scholarly journals Assessment of esophageal body peristaltic work using functional lumen imaging probe panometry

2020 ◽  
Author(s):  
Shashank Acharya ◽  
Sourav Halder ◽  
Dustin A Carlson ◽  
Wenjun Kou ◽  
Peter J. Kahrilas ◽  
...  
Keyword(s):  
Physiological State ◽  
Distal Segment ◽  
Work Capacity ◽  
Mechanical Work ◽  
Lumen Area ◽  
Imaging Probe ◽  
Functional Lumen Imaging Probe ◽  
Using Data ◽  
Secondary Peristalsis ◽  
Work Done

Background: The goal of this study was to conceptualize and compute measures of "mechanical work" done by the esophagus using data generated during functional lumen imaging probe (FLIP) panometry and compare work done during secondary peristalsis among patients and controls. Methods: 85 individuals were evaluated with a 16 cm FLIP during sedated endoscopy, including controls (n=14), achalasia subtypes I, II and III (n=15, each), GERD (n=13), EoE (n=9) and SSc (n=5). The FLIP catheter was positioned to have its distal segment straddling the EGJ during stepwise distension. Two metrics of work were assessed: "active work" (bag volumes ≤ 40 mL where contractility generates changes in lumen area) and "work capacity" (bag volumes ≥ 60 mL when contractility cannot alter the lumen area). Results: Controls showed median (IQR) of 7.3 (3.6-9.2) mJ of active work and 268.6 (225.2-332.3) mJ of work capacity. All achalasia subtypes, GERD, and SSc showed lower active work done than controls (p≤0.003). Achalasia subtypes I, II, GERD, and SSc had lower work capacity compared to controls (p<0.001, 0.004, 0.04, and 0.001 respectively). Work capacity was similar between controls, achalasia type III and EoE. Conclusions Mechanical work of the esophagus differs between healthy controls and patient groups with achalasia, EoE, SSc and GERD. Further studies are needed to fully explore the utility of this approach, but these work metrics would be valuable for device design (artificial esophagus), to measure the efficacy of peristalsis, to gauge the physiological state of the esophagus, and comment on its pumping effectiveness.

Analysis of Fully Developed Unsteady Viscous Flow in a Curved Elastic Tube Model to Provide Fluid Mechanical Data for Some Circulatory Path-Physiological Situations and Assist Devices

1979 ◽  
Vol 101 (2) ◽  
pp. 114-123 ◽  
Author(s):  
K. B. Chandran ◽  
R. R. Hosey ◽  
D. N. Ghista ◽  
V. W. Vayo
Keyword(s):  
Shear Stress ◽  
Unsteady Flow ◽  
Steady Flow ◽  
Pulsatile Flow ◽  
Flow Patterns ◽  
Elastic Tube ◽  
Flow Component ◽  
Flow Response ◽  
Elastic Tubes ◽  
Flow Components

The unsteady and steady flow components of pulsatile flow response, to an experimentally monitored representative pressure pulse, are computed to provide fluid mechanical data for the etiology of arteriosclerosis at arterial curvature sites and for the design analysis of some extracorporeal dialysis and oxygenatory systems. The unsteady flow component of pulsatile flow in curved elastic tubes is simulated by the superposition of the first six Fourier components of a derived oscillatory flow solution of a viscous, incompressible fluid through an elastic tube of small curvature. The computer flow patterns, wall shear stress and hoop and axial stresses in the wall, due to unsteady and steady flow components of pulsatile flow response, are compared and their implications are discussed. The results show that the unsteady component yields shear stress of an order of magnitude greater than the steady flow, but the steady flow component has a greater variation in the shear stress distribution over a cross section. The steady and unsteady flow patterns are presented for several values of the tube diameters and curvature parameters typical of major arteries in the human circulatory system. The flow pattern and the stress variations could also prove useful in the design of extracorporeal systems such as dialysis machines and oxygenators.

Stokes flow in collapsible tubes: computation and experiment

1997 ◽  
Vol 353 ◽  
pp. 285-312 ◽  
Author(s):  
MATTHIAS HEIL
Keyword(s):  
Viscous Flow ◽  
Solid Mechanics ◽  
Stokes Equations ◽  
Applied Pressure ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
External Pressure ◽  
Elastic Tube ◽  
Elastic Tubes ◽  
Wall Deformation

This paper is concerned with the problem of viscous flow in an elastic tube. Elastic tubes collapse (buckle non-axisymmetrically) when the transmural pressure (internal minus external pressure) falls below a critical value. The tube's large deformation during the buckling leads to a strong interaction between the fluid and solid mechanics.In this study, the steady three-dimensional Stokes equations are used to analyse the slow viscous flow in such a tube whose deformation is described by geometrically nonlinear shell theory. Finite element methods are used to solve the large-displacement fluid–structure interaction problem. Typical wall deformations and flow fields in the strongly collapsed tube are shown. Extensive parameter studies illustrate the tube's flow characteristics (e.g. volume flux as a function of the applied pressure drop through the tube) for boundary conditions corresponding to the four fundamental experimental setups. It is shown that lubrication theory provides an excellent approximation of the fluid traction while being computationally much less expensive than the solution of the full Stokes equations. Finally, the computational predictions for the flow characteristics and the wall deformation are compared to the results obtained from an experiment.

scholarly journals Deformation of a Circular Elastic Tube between Two Parallel Bars: Quasi-Analytical Geometrical Ring Models

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
A. Van Hirtum
Keyword(s):  
Cross Section ◽  
Low Cost ◽  
Elastic Tube ◽  
Current Work ◽  
Geometrical Parameters ◽  
Model Choice ◽  
Shape Estimation ◽  
Elastic Tubes ◽  
Ring Shape ◽  
Engineering Problems

Several engineering problems are confronted with elastic tubes. In the current work, homothetic quasi-analytical geometrical ring models, ellipse, stadium, and peanut, are formulated allowing a computationally low cost ring shape estimation as a function of a single parameter, that is, the pinching degree. The dynamics of main geometrical parameters due to the model choice is discussed. Next, the ring models are applied to each cross section of a circular elastic tube compressed between two parallel bars for pinching efforts between 40% and 95%. The characteristic error yields less than 4% of the tubes diameter when the stadium model was used.

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