Peristaltic Wall Research Articles

Lipopolysaccharide accelerates peristalsis by stimulating glucagon-like peptide-1 release from L cells in the rat proximal colon.

Upon epithelial barrier dysfunction, lipopolysaccharide (LPS) stimulates glucagon-like peptide-1 (GLP-1) secretion from enteroendocrine L cells by activating Toll-like receptor 4 (TLR4). Because GLP-1 accelerates peristalsis in the proximal colon, the present study aimed to explore whether LPS facilitates colonic peristalsis by stimulating L cell-derived GLP-1 release. In isolated segments of rat proximal colon that were serosally perfused with physiological salt solution and luminally perfused with 0.9% saline, peristaltic wall motion was video recorded and converted into spatio-temporal maps. Fluorescence immunohistochemistry was also carried out. Intraluminal administration of LPS (100 or 1µgmL-1 but not 100ngmL-1) increased the frequency of oro-aboral propagating peristaltic contractions. The LPS-induced acceleration of colonic peristalsis was blocked by TAK-242 (the TLR4 antagonist), exendin-3 (the GLP-1 receptor antagonist) or BIBN4096 (the calcitonin gene-related peptide receptor antagonist). GLP-1-positive epithelial cells co-expressed TLR4 immunoreactivity. In aspirin-pretreated preparations where epithelial barrier function had been impaired, a lower dose of LPS (100ngmL-1) became capable of accelerating peristalsis. By contrast, luminally applied dimethyl sulphoxide, a reactive oxygen species scavenger that protects epithelial integrity, attenuated the prokinetic effects of a higher dose of LPS (100µgmL-1). In colonic segments of a stress rat model leading to a leaky gut, LPS induced more pronounced prokinetic effects. Colonic L cells may well sense luminal LPS via TLR4 triggering the release of GLP-1 that stimulates calcitonin gene-related peptide-containing neurons. The resultant acceleration of peristalsis would facilitate excretion of Gram-negative bacteria from the intestine, and thus L cells may have a protective role against intestinal bacterial infections. KEY POINTS: Colonic epithelial cells form a barrier against bacterial invasion but also may contribute more actively to the exclusion of luminal pathogen by stimulating colonic motility. Luminal lipopolysaccharide (LPS) accelerated colonic peristalsis by stimulating calcitonin gene-related peptide-containing neurons. The prokinetic effect of LPS was mediated by the secretion of glucagon-like peptide-1 from enteroendocrine L cells in which Toll-like receptor 4 was expressed. The LPS-mediated acceleration of peristalsis depended on epithelial barrier integrity. L cells have a defensive role against Gram-negative bacterial infections by facilitating faecal excretion, and could be a potential therapeutic target for gastrointestinal infections.

Arrangement into layers and mechanobiology of multi-cell co-culture models of the uterine wall.

Can a co-culture of three cell types mimic the in vivo layers of the uterine wall? Three protocols tested for co-culture of endometrial epithelial cells (EEC), endometrial stromal cells (ESC), and myometrial smooth muscle cells (MSMC) led to formation of the distinct layers that are characteristic of the structure of the uterine wall in vivo. We previously showed that a layer-by-layer co-culture of EEC and MSMC responded to peristaltic wall shear stresses (WSS) by increasing the polymerization of F-actin in both layers. Other studies showed that WSS induced significant cellular alterations in epithelial and endothelial cells. Human EEC and ESC cell lines and primary MSMC were co-cultured on a collagen-coated synthetic membrane in custom-designed wells. The co-culture model, created by seeding a mixture of all cells at once, was exposed to steady WSS of 0.5 dyne/cm2 for 10 and 30 min. The co-culture of the three different cells was seeded either layer-by-layer or as a mixture of all cells at once. Validation of the models was by specific immunofluorescence staining and confocal microscopy. Alterations of the cytoskeletal F-actin in response to WSS were analyzed from the 2-dimensional confocal images through the Z-stacks following a previously published algorithm. We generated three multi-cell in vitro models of the uterine wall with distinct layers of EEC, ESC, and MSMC that mimic the in vivo morphology. Exposure of the mixed seeding model to WSS induced increased polymerization of F-actin in all the three layers relative to the unexposed controls. Moreover, the increased polymerization of F-actin was higher (P-value < 0.05) when the length of exposure was increased from 10 to 30 min. Furthermore, the inner layers of ESC and MSMC, which are not in direct contact with the applied shearing fluid, also increased their F-actin polymerization. N/A. The mixed seeding co-culture model was exposed to steady WSS of one magnitude, whereas the uterus is a dynamic organ with intra-uterine peristaltic fluid motions that vary in vivo with different time-dependent magnitude. Further in vitro studies may explore the response to peristaltic WSS or other physical and/or hormonal perturbations that may mimic the spectrum of pathophysiological aspects. Numerous in vitro models were developed in order to mimic the human endometrium and endometrium-myometrium interface (EMI) region. The present co-culture models seem to be the first constructed from EEC, ESC, and MSMC on a collagen-coated synthetic membrane. These multi-cell in vitro models better represent the complex in vivo anatomy of the EMI region. The mixed seeding multi-cell in vitro model may easily be implemented in controlled studies of uterine function in reproduction and the pathogenesis of diseases. This study was supported in part by Tel Aviv University funds. All authors declare no conflict of interest.

Thermal transport of radially magnetized peristalsis of non-Newtonian nanofluid through an asymmetric curved channel

Present examination explores the heat and mass transfer phenomena for magnetohydrodynamics (MHD) peristaltic transport of diethylene glycol (DEG)-based Cross nanofluid through an asymmetric curved channel. The mass and thermal characteristics of nanofluid are established through the assessment of Buongiorno nano-liquid model, which allows to identify intriguing features of thermophoretic and Brownian diffusion coefficients. Further, velocity slip conditions are enforced on the peristaltic walls. The influences of thermal radiation, radius-dependent magnetic field and viscous dissipation are also taken into consideration. The governing equations are simplified by employing lubrication theory (“biological estimate of the creeping transportation phenomenon”), and resulting system is tackled numerically. Impacts of different flow parameters on the nanofluid’s velocity, nanomaterials concentration profile, heat and mass transfer, streamlines, temperature of nanofluid, and stresses at the wall are analyzed via graphs and tables. The findings of this investigation report that nanofluid’s temperature enhances against Hartmann and Brinkman numbers, whereas it declines for the thermal radiation parameter. The distribution of the concentration profile decreases for Brownian motion while it increases for the thermophoresis parameter. Further, a development in the stresses, thermal and mass transfer rates at the boundary is seen for better values of the Hartmann number. Additionally, higher values of the velocity slip parameter show increasing behavior for the velocity of nanofluid near the walls of the channel. The effects of MHD with magnesium aluminate nanoparticles suspended in DEG base fluid-based nanofluid through an asymmetric curved conduit have many uses in industry, organic compounds, biomedical engineering, and commercial productions, such as brake fluid, tobacco, polyester resins, certain dyes, printing ink, polyurethanes, glue, resins, antifreeze, nitrocellulose, oils, cigarettes, plasticizers, and so forth. DEG-based nanofluids are also used in human medications, including acetaminophen and sulfanilamide, which can result in incidents of human poisoning, some of which have been fatal, either intentionally or unintentionally.

Novel study of inertial forces on MHD peristaltically driven micropolar fluid through porous-saturated asymmetric channel: Finite Galerkin approach

This focused study investigates the peristaltic motion of a micropolar fluid within an uneven channel filled with a porous medium, incorporating an orthogonal magnetic field to the flow. This research diverges from the traditional assumptions of lubrication theory. The governing equations, encompassing the physical characteristics of micropolar fluid peristalsis, are transformed into nonlinear coupled partial differential equations. These equations are solved using the finite element method, considering inertial effects, such as non-zero wave and Reynolds numbers. This study delves into the influence of various crucial parameters on axial velocity, pressure gradient, microrotation, and stream function, presenting graphical representations. Notably, the incremental phase shift causes an intermingling of upper and lower streamlines within both halves of the channel. As the Reynolds number increases, there is an observed reduction in bolus size, particularly at maximum phase shifts, with a tendency to move toward the central region. An increase in Hartmann number leads the bolus formation to vanish in both channels, reduces microrotation, and leads to increased pressure. Vorticity lines intensify and incline toward the peristaltic walls. An increase in the permeability parameter amplifies velocity, microrotation, volume, and bolus formation regardless of phase differences while countering pressure elevation per wavelength. Reduced concavity is observed as vorticity lines disperse across the entire area.

Analytical solution of non-Newtonian Williamson fluid under the effect of magnetohydrodynamics

In this paper, inscribed non-Newtonian Williamson fluid relaxation and contraction phenomena due to the effect of magnetohydrodynamics (MHD) is taken into account. This issue is modeled, and precise solutions are handled using a low Reynolds number and long wavelength approximation. Graphical depiction of the consequences of various parameters on temperature and velocity are provided. It becomes clear that the temperature reactions to increases in Biot numbers are decreased. Considering a cylindrical coordinate system, the impact of various physical parameters on the temperature distribution, velocity, the pressure gradient, and frictional force are secured from the flow for non-Newtonian Williamson fluid exposed from MATLAB. Additionally, it has been discovered that the velocity profile at the tube’s center increases for shear-thinning a fluid and decreases for thickening a fluid. Furthermore, the peristaltic walls show the opposite behavior.

Hall impact on peristaltic stream of Prandtl hybrid nano-blood via a tapered endoscopic annular vessel with blood clotting

This research article is proposed to frame and simulate the peristaltic transport mechanism with heat and mass transfer behavior of bloodstream infused with hybridized nanoparticles (Cu and CuO) via a tapered endoscopic annular vessel under the act of highly strengthened magnetic and buoyancy forces. The consequences of Brownian motion, thermophoresis, heat source, viscous and Joule heating are presumed for heat and mass transport examination. Darcy law is postulated to describe the porous medium's attribute to the blood flow dynamics. Prandtl fluid model is invoked to emulate the non-Newtonian behavior of the blood with the suspension of hybridized nanoparticles. The modeled equations are condensed by employing the lubrication approach. The homotopy perturbation technique is implemented to determine the optimal series solution of the coupled nonlinear subsequent equations. The physical aspects of diverse emerging parameters on the underlying hemodynamical features are delineated and pondered via plotting graphs. The trapping event is elucidated in the form of contour designs. Outcomes extract that a higher Hartmann number depreciates the blood motion adjacent to the peristaltic wall, while the opposing manner attends for augmenting Hall parameter. It is also testified that more trapped boluses are generated for hybrid nano-blood (Cu-CuO/blood) contrasted with other cases.

Unsteady flow of hybrid fluid via peristaltic pumping in wavy micro-channel under electric and magnetic field effects: An application of Hall device and slip boundary

Aim of study In the current analysis, the blood is used as a viscoelastic fluid and manipulated with an electromagnetic field because of its magnetic features. Furthermore, blood is considered as a non-Newtonian fluid that is productive in nano- and micro-scales transport. To study the performance of hybrid fluids, a selection of nanofluids is examined with a Jeffrey fluid (blood) which is doped with [Formula: see text] and [Formula: see text] nanoparticles. Mathematical formulation The long wavelength assumption, lubrication theory and Debye–Huckel linearization are employed. Analytical solutions of flow equations are implemented in Mathematica by using integration technique. The impacts of considered parameters on the flow are computed. Combined influence of Hall device, momentum, and thermal slips is observed on various flow features. Outcomes Magnitude of the velocity goes on decreasing by increasing magnetic and viscoelastic parameters. The wavy behavior is predicted in the graphs of pressure gradient due to the complex nature of peristaltic walls. Enhancing the viscoelastic effects and concentration of nanoparticles results in reduction of magnitude of the pressure gradient. Heat transfer of hybrid fluid is larger in steady state flow as compared to the unsteady state. The heat source/sink parameter has remarkable impacts on enhancement of heat transfer phenomena of viscoelastic hybrid fluid. Applications The present investigation is relevant to electromagnetic hybrid liquid micropump manufactures and emerging nano-physiological technologies.

Channel flow of non-Newtonian fluid due to peristalsis under external electric and magnetic field

The overall objective of the current analysis is to examine how electroosmotic flow combined with peristaltic pumping phenomenon could ably contribute to intracellular fluid flow. The biofluid is taken as non-Newtonian Couple stress fluid, while micro-passage is approximated as two-dimensional inclined channel comprehending complex peristaltic walls. Following a traditional approach of peristaltic fluid flow problem balance of mass and momentum is utilized. Beside channel waves, flow is also generated by Lorentz force triggered by electric and magnetic fields. To integrate electric potential term Poisson-Boltzmann and Nernst Planck equation are utilized. Finally, a sixth order BVP in term of stream function is obtained by employing creeping flow, long wavelength and Debye-Hückel assumptions. A numerical solution is calculated and analyzed by plotting fluid velocity and level curves in MATLAB 2021b. It is observed that couple stress fluid flows with greater speed (in central region of the channel) as compared to Newtonian fluid. Moreover, electro-osmotic parameter and Debye-Hückel length are assistive factors to the fluid velocity in the lower half of the passage.

Galerkin finite element analysis for peristaltic flow of micropolar fluid through porous soaked inclined tube independent of wavelength

In this novel numerical investigation, the application of well-renowned numerical technique known as Galerkin finite element method on full form of Navier-Stokes equations presented peristaltic flow of non-Newtonian fluid confined by a uniformly saturated porous medium. The rheological aspects of non-Newtonian material are discussed by considering micropolar fluid. The flow model consists of system of nonlinear partial differential equations with mixed boundary condition. The flow also experienced an externally applied magnetic field. The effects of inertial forces and the results independent of wavelength are obtained by dropping the presumptions of lubrication theory in modelling the governing equations. The numerical solution for formulated problem in terms of partial differential expressions is worked out via Galerkin finite technique in view of six nodal triangular elements. The enhancement in the inertial forces gives impressive pressure enhancement against wavelength while opposed the fluid flow in the vicinity of peristaltic walls of the tube but supported the fluid flow in the central region of the tube. The present results are also compared with the available results after applying lubrication theory and found in reliable agreement.

Study of Heat Characteristics of Electroosmotic Mediator and Peristaltic Mechanism via Porous Microtube

Heat characteristics of electroosmotic peristaltic flow are investigated in the porous microtube. Flow and heat equations are modeled using the Jeffrey fluid and viscous dissipation, respectively. The wall is patterned with a periodic array of sinusoidal peristaltic waves. In the presence of axial electric field, the chemical interaction of electrolyte (Jeffrey fluid) and the peristaltic walls (solid) cause an electric double layer at the interface. Based on low Reynolds assumption and Debye-Huckel linearization, the Poisson-Boltzmann equation formally solves the potential distribution, and the resulting non-linear problem is numerically solved via the NDSolve built-in scheme of the computing software Mathematica. Expression of interest like electric potential, velocity, pressure gradient, temperature, streamlines, and wall shear stress are executed numerically within the Jeffrey fluid flow pattern. A complete parametric study is executed to find out the outturn of material parameter λ1, permeability of porous medium K, electroosmotic parameter me, mobility of the medium β, and Brinkman number Br on the thermal features of the flow. This model is also suitable for a wide range of biological microfluidic applications. It is observed that the morphology of heat transfer in the flow is found to be subject to the joint consequence of the geometry of the tube and wall properties. The axial velocity increases monotonically for the Jeffrey fluid when equated to the viscous fluid. Moreover, velocity is noticed to upsurge with higher values of electroosmotic parameter and declines for porous medium and mobility of medium. The magnitude of bolus is larger for the case of Newtonian fluid as compared with non-Newtonian Jeffery fluid. Porosity decays the temperature throughout the microtube. The results presented may potentially be applied to clinical cases associated with the intrapleural membranes, gastrointestinal tract, and capillaries.

Effects of solid particles on fluid-particulate phase flow of non-Newtonian fluid through eccentric annuli having thin peristaltic walls

The current theoretical and mathematical treatments deal with the occurrence of solid particles in the peristaltic stream of Jeffrey fluid traveling in an annular region of two eccentric tubes. The influence of porous space and magnetohydrodynamics is also taken into intent. The passage is considered inside the space between two annuli having different center lines. The smaller tube is taken to be hard, and the outer annulus is having elastic walls, producing waves along its linear orientation. The flow is considered to be incompressible by the supposition of small wave number and negligible turbulence effects. The obtained flow equations for dual phases have been handled by an analytical highly convergent approach. The results achieved for basic features have been sketched against corresponding coordinates beneath the variation of some pertinent parameters. It is mainly concluded from this study that solid particles are slowing down the flow with the increase in their quantity as well as their volume and also reduce the pumping rate. It is also point of consideration that solid particles are cause of increasing peristaltic pumping. Moreover, the trapping boluses are decreasing their numbers but expand their area by increasing amount of solid particles. The flow rate can be made better by continuously reducing the size of solid particles mechanically.

Tissue engineered endometrial barrier exposed to peristaltic flow shear stresses.

Cyclic myometrial contractions of the non-pregnant uterus induce intra-uterine peristaltic flows, which have important roles in transport of sperm and embryos during early stages of reproduction. Hyperperistalsis in young females may lead to migration of endometrial cells and development of adenomyosis or endometriosis. We conducted an in vitro study of the biological response of a tissue engineered endometrial barrier exposed to peristaltic wall shear stresses (PWSSs). The endometrial barrier model was co-cultured of endometrial epithelial cells on top of myometrial smooth muscle cells (MSMCs) in custom-designed wells that can be disassembled for mechanobiology experiments. A new experimental setup was developed for exposing the uterine wall in vitro model to PWSSs that mimic the in vivo intra-uterine environment. Peristaltic flow was induced by moving a belt with bulges to deform the elastic cover of a fluid filled chamber that held the uterine wall model at the bottom. The in vitro biological model was exposed to peristaltic flows for 60 and 120 min and then stained for immunofluorescence studies of alternations in the cytoskeleton. Quantification of the F-actin mass in both layers revealed a significant increase with the length of exposure to PWSSs. Moreover, the inner layer of MSMCs that were not in direct contact with the fluid also responded with an increase in the F-actin mass. This new experimental approach can be expanded to in vitro studies of multiple structural changes and genetic expressions, while the tissue engineered uterine wall models are tested under conditions that mimic the in vivo physiological environment.

The impacts of varying magnetic field and free convection heat transfer on an Eyring–Powell fluid flow with peristalsis: VIM solution

A mathematical model of a non-Newtonian fluid (Eyring–Powell fluid) flow with peristalsis under the effect of varying magnetic field and free convection heat transfer has been discussed. Most of the previous attempts of peristaltic flow problems for a non-Newtonian fluid have been solved by using the perturbation technique for a small non-Newtonian parameter, which gives some limits for the results. To avoid such restriction, the variational iteration method (VIM) is applied to solve the current model. A code is established by using the symbolic software MATHEMATICA to get the successive solutions. Semi-analytical solutions are found by VIM for the velocity, heat transfer, pressure gradient and stream function, which include Eyring–Powell fluid parameters. Moreover, a comparison between VIM and numerical solutions is discussed. The obtained results show that the variation of the heat transfer for the Newtonian fluid is large compared with the Eyring–Powell fluid. In addition, it is noteworthy that the peristaltic transport overcomes on Lorentz force nearby the peristaltic walls.

Peristalsis of carbon nanotubes with radiative heat flux

The purpose of this analysis is to highlight the CNTs characteristics in peristaltic flows through non-uniform channels. Viscosity is considered temperature in this analysis. Peristaltic walls comprise the momentum and thermal slip effects. Radiative heat flux is also taken into account to study the thermal radiation aspects. Physical properties for CNTS (i.e. single and multiple wall) are used which was suggested by Iijima. Flow equations are modeled in view of mass, momentum and energy conservation principles. Moreover, such equations are simplified through lubrication assumptions. Solution for flow quantities is carried out in the form of exact solution. Numerical integration technique is used for pressure rise per wavelength plotting. Bar charts are made for effective heat transfer rate analysis.

Rheological and magnetic effects on a fluid flow in a curved channel with different peristaltic wave profiles

Peristalsis is one of the most dynamic phenomena that is significantly applicable to biomedical engineering. Motivated by such fact, the current article deals with the numerical simulation of magnetically induced fluid flow bounded within two curved peristaltic walls. Fluid rheology is approximated by linearly viscoelastic Jeffrey fluid, while five different wave profiles are utilized to capture the peristaltic effects. A constant magnetic field is also applied in the radial direction. The constitutive equations in curvilinear coordinates are reduced under the lubrication theory. The reduced boundary value problem is further solved by MATLAB built-in routine BVP6C. The axial velocity, pressure rise and stream function are numerically obtained in the wave frame. The impacts of different peristaltic wave profiles and several embedded parameters, for example, the dimensionless radius of curvature, magnetic parameter (Hartmann number) and viscoelastic parameter, respectively, on the flow characteristics are shown through graphs and discussed in detail. Boundary layer phenomena are also highlighted for large values of the Hartmann number and the ratio of relaxation to retardation time parameter for different peristaltic waves. A special case of the straight channel is also retrieved from a large curvature parameter. This study provides fruitful information to understand the flow phenomena of blood, foods, nutrients and liquids that pass through non-uniform veins or arteries.

Corrigendum to “Optimization of SWCNTs and MWCNTs (single and multi-wall carbon nanotubes) in peristaltic transport with thermal radiation in a non-uniform channel” [J. Mol. Liq. 273(2019) 383–391

• Carbon nanotubes are considered. • Viscosity is taken as a function of temperature. • Effective heat transfer at lower and upper walls are discussed. • Velocity and thermal slip conditions comprises at peristaltic walls. • Thermal radiation effects are taken.

Peristaltic biofluids flow through vertical porous human vessels using third-grade non-Newtonian fluids model.

In this paper, the heat and flow characteristic of third-grade non-Newtonian biofluids flow through a vertical porous human vessel due to peristaltic wall motion are studied. The third-grade model can describe shear thinning (or shear thickening) and normal stress differences, which is acceptable for biofluids modeling. In order to solve the governing equations, the assumption of long-wavelength approximation is utilized. This hypothesis emphasizes that the wavelength of the peristaltic wall motion is large in comparison with the radius of the human vessel, which is widely acceptable in biological investigations. The analytical perturbation method is employed to solve the governing equations. Consequently, analytical expressions for the velocity profile, shear stress, temperature field, and biofluid flow rate are obtained. In addition, the effects of the governing parameters such as the third-grade non-Newtonian parameter, Grashof Number, Eckert number, and porosity, on the results are examined.

The Flow Separation of Peristaltic Transport for Maxwell Fluid between Two Coaxial Tubes

We study the peristaltic mechanism of an incompressible non-Newtonian biofluid (namely, Maxwell model) in the annular region between two coaxial tubes. The inner tube represents the endoscope tube. The system of the governing nonlinear PDE is solved by using the perturbation method to the first order in dimensionless wavenumber. The modified Newton-Raphson method is used to predict the flow separation points along the peristaltic wall and the endoscope tube. The results show that the presence of the endoscope (catheter) tube in the artery increases the pressure gradient and shear stress. Such a result seems too reasonable from the physical and medical point of view.

Unsteady Flow of Magneto Thermomicropolar Fluid in a Porous Channel With Peristalsis: Unsteady Separation

The magneto thermodynamic aspects of micropolar fluid (blood model) through an isotropic porous medium in a nonuniform channel with rhythmically contracting walls have been investigated. The flow analysis has been discussed under long wavelength and low Reynolds number approximations. The closed form solutions are obtained for velocity components, microrotation, heat transfer, as well as the wall vorticity. The modified Newton–Raphson method is used to predict the unsteady flow separation points along the peristaltic wall. Numerical computations have been carried out for the pressure rise per wavelength. The study shows that peristaltic transport, fluid velocity, microrotation velocity, and wall shear stress are significantly affected by the nonuniform geometry of the blood vessels. Moreover, the amplitude ratio, the coupling number, the micropolar parameter, and the magnetic parameter are important parameters that affect the flow behavior.

The influence of heat transfer on peristaltic transport of a Jeffrey fluid in a vertical porous stratum

The peristaltic flow of a Jeffrey fluid in a vertical porous stratum with heat transfer is studied under long wavelength and low Reynolds number assumptions. The nonlinear governing equations are solved using perturbation technique. The expressions for velocity, temperature and the pressure rise per one wave length are determined. The effects of different parameters on the velocity, the temperature and the pumping characteristics are discussed. It is observed that the effects of the Jeffrey number λ 1, the Grashof number Gr, the perturbation parameter N = EcPr, and the peristaltic wall deformation parameter ϕ are the strongest on the trapping bolus phenomenon. The results obtained for the flow and heat transfer characteristics reveal many interesting behaviors that warrant further study on the non-Newtonian fluid phenomena, especially the shear-thinning phenomena. Shear-thinning reduces the wall shear stress.