Elastic Tube Research Articles

Analysis of modulational instability of waves in the fluid-filled elastic tube

In this paper, we investigate the modulational instability of waves within a fluid-filled elastic tube considering the fluid viscosity. Through the reductive perturbation method, we derived a modified Nonlinear Schrödinger Equation (NLSE) with damping term for the system. Based on the modified NLSE, we found that modulational instability exists in this system though the fluid viscosity is considered. Both the instability and the stability region are given. Furthermore, the growth rate of the instability is obtained. The dependence of the growth rate on the system parameters such as perturbation wave length, the background wave length, the viscosity of the fluid and the elasticity of the tube is given in the present paper. It indicates that the fluid viscosity refrain the modulational instability. The results may be used to predict the production of the rogue wave in this system, as well as to the other similar system.

Soret and Dufour Effects on MHD Fluid Flow Through a Collapssible Tube Using Spectral Based Collocation Method

This paper examine numerical study for soret and dufour effects on unsteady Newtonian MHD fluid flow with mass and heat transfer in a collapsible elastic tube using Spectral Collocation technique. The objective of the study is to determine the velocity, temperature and concentration profiles together with heat and mass transfer rates. The governing equations are continuity, momentum, energy and concentration equation. The system of nonlinear partial differential equations governing the flow solved numerically by applying collocation method and implemented in MATLAB. The numerical solution of the profiles displayed both by graphically and numerically for different values of the physical parameters. The effects of varying various parameters such as Reynolds number, Hartmann number, Soret number, Dufour number and Prandtl number on velocity, temperature and concentration profiles also the rates of heat and mass transfer are discussed. The findings of this study are important due to its wide range of application including but not limited to medical fields, biological sciences and other physical sciences where collapsible tubes are applied.

Tube law parametrization using in vitro data for one-dimensional blood flow in arteries and veins: TUBE LAW PARAMETRIZATION IN ARTERIES AND VEINS.

The deformability of blood vessels in one-dimensional blood flow models is typically described through a pressure-area relation, known as the tube law. The most used tube laws take into account the elastic and viscous components of the tension of the vessel wall. Accurately parametrizing the tube laws is vital for replicating pressure and flow wave propagation phenomena. Here, we present a novel mathematical-property-preserving approach for the estimation of the parameters of the elastic and viscoelastic tube laws. Our goal was to estimate the parameters by using ovine and human in vitro data, while constraining them to meet prescribed mathematical properties. Results show that both elastic and viscoelastic tube laws accurately describe experimental pressure-area data concerning both quantitative and qualitative aspects. Additionally, the viscoelastic tube law can provide a qualitative explanation for the observed hysteresis cycles. The two models were evaluated using two approaches: (i) allowing all parameters to freely vary within their respective ranges and (ii) fixing some of the parameters. The former approach was found to be the most suitable for reproducing pressure-area curves.

Estimation of the composition ratio of two contents filled in an elastic thin tube through laser-diode-based photoacoustic measurements

Photoacoustic imaging is considered useful for evaluating the effects of treatment because it has a good resolution to capture minute vascular lesions and changes in the progression of atherosclerosis, which is difficult to detect with conventional imaging methods. In this study, the authors prepared a thin silicone tube filled with a mixture of red ink and olive oil as a model that mimics arteriosclerosis. The tube was embedded in a soft phantom. Photoacoustic measurements were performed using 405 nm and 520 nm laser diodes. As a result, the 405 nm laser produced a higher photoacoustic signal as the oil concentration in the mixture increased, whereas the 520 nm laser produced lower photoacoustic signals as the oil concentration increased. By focusing on the difference in the optical absorption at different wavelengths between the red ink and oil, it was shown that there was a possibility of estimating the oil concentration from the ratio of photoacoustic signals between different wavelengths.

Thermal effects of power-law fluid in an elastic tube

A mathematical model is used to study the impact of elasticity on the peristaltic flow of a Power-Law fluid including nanoparticles in a cylindrical tube. Long wavelength and low Reynold's number approximations and non-dimensionalization are used in the governing equations to get non-linear equations. Homotopy Perturbation Method is an approximate analytical method, which is used here to solve coupled equations of Temperature profile and nanoparticle phenomena. Then the expression for axial velocity and flux flow rate are calculated. The techniques of Rubinow, Keller, and Mazumdar are used to compute the flux variation. The impact of various factors on flow is addressed. The change in Heat and Mass transfer coefficients are studied at the end. A number of intriguing behaviors are reported by the results obtained for the current flow characteristics, which call for more research on physiological fluids in elastic tubes with peristalsis. In this work, the wide variety of applications of nanofluids is presented with an emphasis on their enhanced, regulated heat transfer qualities. Because of their special qualities, these nanofluids are appropriate for a variety of uses. The work has applications in pharmacological engineering, such as peristaltic micropumps and innovative drug delivery methods.

Waves in an elastic tube with flowing liquid in the case of recording stiffness environment

Waves in an elastic tube with flowing liquid in the case of recording stiffness environment

Elastic Tube Model Predictive Control With Scaled Zonotopic Sets

Elastic Tube Model Predictive Control With Scaled Zonotopic Sets

Mechanism Analysis of Forced Induced Wave Evaporation Heat Transfer by Liquid Film outside Elastic Tube Bundle

Mechanism Analysis of Forced Induced Wave Evaporation Heat Transfer by Liquid Film outside Elastic Tube Bundle

Dynamic Computed Tomography Angiography for capturing vessel wall motion: A phantom study for optimal image reconstruction.

Reliably capturing sub-millimeter vessel wall motion over time, using dynamic Computed Tomography Angiography (4D CTA), might provide insight in biomechanical properties of these vessels. This may improve diagnosis, prognosis, and treatment decision making in vascular pathologies. The aim of this study is to determine the most suitable image reconstruction method for 4D CTA to accurately assess harmonic diameter changes of vessels. An elastic tube (inner diameter 6 mm, wall thickness 2 mm) was exposed to sinusoidal pressure waves with a frequency of 70 beats-per-minute. Five flow amplitudes were set, resulting in increasing sinusoidal diameter changes of the elastic tube, measured during three simulated pulsation cycles, using ECG-gated 4D CTA on a 320-detector row CT system. Tomographic images were reconstructed using one of the following three reconstruction methods: hybrid iterative (Hybrid-IR), model-based iterative (MBIR) and deep-learning based (DLR) reconstruction. The three reconstruction methods where based on 180 degrees (half reconstruction mode) and 360 degrees (full reconstruction mode) raw data. The diameter change, captured by 4D CTA, was computed based on image registration. As a reference metric for diameter change measurement, a 9 MHz linear ultrasound transducer was used. The sum of relative absolute differences (SRAD) between the ultrasound and 4D CTA measurements was calculated for each reconstruction method. The standard deviation was computed across the three pulsation cycles. MBIR and DLR resulted in a decreased SRAD and standard deviation compared to Hybrid-IR. Full reconstruction mode resulted in a decreased SRAD and standard deviations, compared to half reconstruction mode. 4D CTA can capture a diameter change pattern comparable to the pattern captured by US. DLR and MBIR algorithms show more accurate results than Hybrid-IR. Reconstruction with DLR is >3 times faster, compared to reconstruction with MBIR. Full reconstruction mode is more accurate than half reconstruction mode.

Exercise-Induced Transient Oxidative Stress Is Mitigated in Down Syndrome: Insights About Redox Balance and Muscle Strength.

Reis, AL, Deus, LA, Neves, RVP, Corrêa, HL Reis, TL, Aguiar, LS Honorato, FS, Barbosa, JMS, Araújo, TB, Palmeira, TRC, Simões, HG, Prestes, J, Sousa, CV, Ide, BN, and Rosa, TdS. Exercise-induced transient oxidative stress is mitigated in Down syndrome: insights about redox balance and muscle strength. J Strength Cond Res 38(3): e125-e34, 2024-This study aimed to evaluate the acute effects of a session of resistance exercise (RE) performed with elastic tubes on the redox balance and inflammatory profile in individuals with Down syndrome (DS). Subjects ( n = 23) were allocated into 2 groups: individuals with DS (DS; n = 11) and individuals without DS (WDS; n = 12), who performed an acute RE session. Diagnostic assessment included medical history, anthropometric measures (body height, body mass, body mass index, and body composition assessment), biological collections, muscle strength assessments (handgrip and maximal voluntary isometric contraction tests), and exercises. The redox balance and inflammatory profile were assessed in urine and saliva samples before and after an acute RE session. There were no differences between WDS and DS groups for body composition ( p > 0.05). The DS group presented higher values pre and post an acute RE session with elastic tubes for oxidative and proinflammatory markers compared with WDS ( p < 0.05). Uric acid values increased from pre-acute RE session to post-acute RE session for WDS ( p < 0.0001). No differences were identified within groups for the delta analysis ( p > 0.05). Inverse correlations were found between total force and F2-isoprostane, 8OHdG, uric acid, allantoin, IL-6, TNF-α, and the TNF-α:IL-10 ratio. A positive correlation was found between IL-10 and total force. The DS group presented increased peak force in the knee extension and elbow flexion exercises (∼25 and 12%, respectively) but decreases in handgrip strength of ∼7%. The WDS group showed higher peak force values for knee extension, elbow flexion, and handgrip (∼16, 10, and 14%, respectively). The DS group had lower transient elevation of oxidative stress after an acute RE session compared with WDS. Oxidative stress and inflammation responses of DS to an acute RE session with elastic tubes may be insufficient to induce health adaptations for the same relative load compared with WDS.

Elasticity Amelioration in transporting blood flow within curved stenotic tubes

AbstractIn biomechanical devices, blood can be transfused through small, curved walls. Accordingly, this research highlights the study of blood flow in cases of stenosis of the elastic artery with curvature. The effects of bending on the shear and resistance through this elastic tube have been investigated. The moderate stenosis case has been used to simulate the governing equations for an incompressible and steady non‐Newtonian fluid, or “tangent hyperbolic fluid”. A perturbation technique has been used to obtain an analytical solution. The Rubinow &amp; Keller model [24] simulates the flexibility of the stenosis artery walls. The results showed that increasing the parameters linked to the walls' flexibility made it easier for blood to flow through the stenosis area, which emphasizes the need for a thorough investigation of non‐Newtonian fluid flow phenomena. One of the most important threats facing humanity is blood stenosis. In microvasculature, there are many conditions in which the blood vessels are curved or twisted, especially in the case of disease.

Numerical study on the effect of baffle structure on the heat transfer performance of elastic tube bundle heat exchanger

To make up for the research gaps in the existing literature on the effect of baffle structural parameters on the vibration and heat transfer of elastic tube bundle (ETB) heat exchangers, and improve the comprehensive heat transfer performance (HTP) of heat exchangers, based on an improved elastic tube bundle (I-ETB) heat exchanger used in previous studies, using the bi-directional fluid-structure interaction calculation method, the effects of the baffle structure improvement (height and curvature) on the comprehensive HTP of the I-ETB heat exchanger at different inlet velocities (Uin) were numerically studied. The results show that: while the height factor increases from 0.70 to 0.80, the vibration amplitude of I-ETBs decreases maximum by 10.05 %, and the heat transfer coefficient (h) of I-ETB increases maximum by 5.50 %. Increasing the baffle height improves the comprehensive HTP while suppressing the vibration of the I-ETBs. While the baffle curvature is 10°, the vibration of I-ETBs is the most intense, with the amplitude of the I-ETBs improving maximum by 10.79 %. The Nusselt number per unit pressure drop Nu/ΔP and performance evaluation criteria PEC and JF (a dimensionless number related to Colburn factor j and Fanning friction factor f) values of the heat exchanger all reach the maximum while the baffle curvature is 10°. The increase of baffle curvature has a positive effect on the vibration-enhanced HTP of the I-ETBs, and when the curvature is 10°, the comprehensive HTP of the heat exchanger is better.

Experimental and theoretical analysis of pulsatile flow in elastic tubes: Wave propagation and attenuation

The objective of this study was to comprehensively examine the pulsatile flow behavior within an elastic tube using experimental and theoretical approaches. This work is an extension of our earlier report [Roknujjaman et al., Phys. Fluids, 34, 123612 (2022)]. In this paper, we adapted a quasi-one-dimensional model to elucidate the wave propagation and pulse attenuation phenomena in an elastic tube and compared with experimental findings. According to our investigation, the key findings were as follows: the experimental and predicted flow wave propagation trend agreed well. Additionally, because of the silicon tubes greater deformation than the urethane tubes, the pulsation was decreased farther in the silicon tubes than in the urethane ones. Furthermore, because of the reflected wave near the tube exit, the pulsations amplitude significantly increased, but it did not enlarge when the resistance was installed at the exit. Finally, we infer that the quasi-one-dimensional model is a better fit for experimental results compared to the two-dimensional model.

Unified and accurate simulation for large elastic strain responses of rubberlike soft materials under multiple modes of loading

AbstractA new and explicit form of the multi-axial elastic potential for elastic soft materials is constructed by means of two invariants of the Hencky strain. The new elasticity model with this form can bypass coupling complexities and uncertainties usually involved in parameter identification. Namely, exact closed-form solutions of decoupled nature are obtainable for stress responses under multiple benchmark modes. Unlike usual solutions with numerous coupled parameters, such new solutions are independent of one another and, as such, data sets for multiple benchmark modes can be separately matched with mutually independent single-variable functions. A comparative study is presented between a few well-known models and the new model. Results show that predictions from the former agree well with uniaxial and biaxial data, as known in the literature, but would be at variance with data for the constrained stress response in the plane-strain extension. In contrast, predictions from the new model agree accurately with all data sets. Furthermore, exact solutions for the Poynting effect of freely twisted elastic thin-walled tube are obtained from the new model.

A Spectral Method Algorithm for Modeling the Dispersion of Non-Axisymmetric Modes in Fluid-Filled Elastic Tubes

In order to design a low-noise water-filled pipeline system, it is necessary to obtain knowledge of the dispersion characteristics of axial propagation modes in different water-filled elastic tubes. In this work, an algorithm is developed based on the spectral method, which has previously been used to solve the dispersion of axisymmetric modes in cylindrical structures but has not yet been applied to non-axisymmetric modes. The algorithm can obtain the dispersion characteristics, modal displacement, and stress distribution of axial propagation modes in a fluid-filled elastic multi-layer tube. The algorithm behaves well both at low and ultrasonic frequencies, and it is suitable for any tube dimensions, wall thickness and layers. The results of a water-filled PMMA tube obtained using the spectral method algorithm were verified using a COMSOL simulation, while the dispersion curves of the same tube from the literature were found to be missing some low-order modes. In addition, the dispersion curves of a water-filled three-layer tube are given. The spectral method algorithm has the advantages of fast calculation speed, less computational resources consumed, accurate results, and no modal omission.

WKB analysis of the bifurcation for a three-dimensional neo-Hookean cylindrical tube under restricted compression

We study the bifurcation of a three-dimensional neo-Hookean elastic cylindrical tube under axial compression, where the movement of the outer surface is restricted. For the first time, the WKB method is applied to the three-dimensional eigenvalue problem and the bifurcation conditions are calculated for thick and thin-walled cylinders, separately. In this paper, two WKB expansions are considered for the two cases (i.e. for large axial or circumferential mode number) and the asymptotic expansion of the eigenvalue is obtained for each case separately. It is found that the changes of the axial stretch relative to the thickness of the cylinder have a boundary layer structure. The dependency of the axial stretch on the mode numbers, length and the wall thickness is assessed. The critical stretches occur for the finite critical mode numbers and are an decreasing function of the thickness of the tube, so thick cylinders are easier to buckle. Also, transitions between axial and circumferential modes occur in three points for mode numbers of 10,20 and at a point for mode number of zero. Using the compound matrix method to verify the analytical results, the comparison of outcomes of the numerical and analytical data shows a good agreement.

An accurate and parameter‐free analysis for the converse Poynting effect in large constrained torsion of highly elastic soft tubes

AbstractNew exact solutions to large constrained torsion of highly elastic soft tubes are obtained from a new hyper‐elastic constitutive model. This new model is established with a new form of the multiaxial elastic potential toward simultaneously matching multiple data sets for three benchmark modes, including the uniaxial extension of a bar, the equi‐biaxial extension of a thin plate and the plane‐strain extension of a plate strip. With the new model, exact closed‐form solutions to the stress responses for these benchmark modes are first derived and shown to be of decoupled nature, and, then, an accurate analysis for the converse Poynting effect of twisted highly elastic tubes with fixed ends is presented with a new technique in treating nonlinear coupling complexities. The main novelties are incorporated as follows. First, multiple data sets for three benchmark modes can be accurately and automatically matched with no need to identify any unknown parameters; next, the nonlinear coupled system of the governing equations for four variables in a twisted tube, including the averaged radius and the wall‐thickness as well as the axial constrained stress and the shear stress, can be reduced to treating a single nonlinear equation; and, accordingly, the nonlinear coupling complexities can be worked out and exact results are obtainable.

RT-DLO: Real-Time Deformable Linear Objects Instance Segmentation

Deformable Linear Objects (DLOs) such as cables, wires, ropes, and elastic tubes are numerously present both in domestic and industrial environments. Unfortunately, robotic systems handling DLOs are rare and have limited capabilities due to the challenging nature of perceiving them. Hence, we propose a novel approach named <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RT-DLO</i> for real-time instance segmentation of DLOs. First, the DLOs are semantically segmented from the background. Afterward, a novel method to separate the DLO instances is applied. It employs the generation of a graph representation of the scene given the semantic mask where the graph nodes are sampled from the DLOs center-lines whereas the graph edges are selected based on topological reasoning. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">RT-DLO</i> is experimentally evaluated against both DLO-specific and general-purpose instance segmentation deep learning approaches, achieving overall better performances in terms of accuracy and inference time.

The modulations of higher order solitonic pressure and energy of fluid filled elastic tubes

In this article, we investigate the weak higher order nonlinear solitonic pressure waves in elastic, incompressible, nonviscous fluid-filled tubes. The higher order Korteweg–de Vries equation has been developed from the perturbed nonlinear equation. The dependence of higher-order solitonic pressure, higher order fluid velocity, and higher order solitonic energy on the nonlinear coefficient and the perturbation parameter has been established. The presented solutions will be more beneficial in the several disciplines of blood flow and many other related fields of applied science.

One-dimensional haemodynamic model of a vascular network with fractional-order viscoelasticity

Abstract We propose a computational framework for a one-dimensional haemodynamic model with the arterial walls described by the fractional-order viscoelastic material constitutive law. This framework is used to compare blood flow characteristics for simulations with elastic and fractional-order viscoelastic walls. We use three well-established benchmark tests: a single pulse wave in a long vessel, flow in a 37-segment network of elastic tubes, and flow in anatomically detailed arterial network consisting of 61 arterial segments. All results for elastic model are in a good agreement with analytical solutions, in vitro data and other well-established approaches. Fractional-order model demonstrates noticeable differences in pulse wave propagation speed and minor differences in pressure and flow profiles. Differences in profiles are negligible in major vessels, but more profound in vessels beyond the third or fourth generation.