Interfacial transport processes and rheology

Mass transport on chemicalized fourth-grade fluid propagating peristaltically through a curved channel with magnetic effects

In this article, the intra-uterine flow with small suspended particles under the impact of heat transfer is investigated. Intra-uterine fluid motion occurs in a non-pregnant uterus which is essential for examining the embryo movement in a uterus. It also plays a key role in assisting sperm movement to the fallopian tube. The Jeffrey fluid through a tapered channel with compliant boundary walls is taken into account. The proposed Jeffrey fluid model has the following features. It is electrically conducting, incompressible, irrotational with constant density, etc. The mathematical formulation is conducted under the lubrication approach for both fluid and particulate phases. The formulated equations are linearly coupled, which are solved with the help of computational software, and the exact solutions for temperature and velocity profile are presented. The influence of key parameters for velocity, and thermal profiles is illustrated graphically. It is observed that the graphical results are in accordance with the physical expectations. The presented analysis is believed to aid in reducing the risk of miscarriages and fetal withering. The obtained results are helpful in examining the embryo transfer and hydrosalpinx.

Intra-uterine particle–fluid motion through a compliant asymmetric tapered channel with heat transfer

An analysis is presented in this work to assess the influence of micropolar nature of fluids in fully developed flow induced by electrokinetically driven peristaltic pumping through a parallel plate microchannel. The walls of the channel are assumed as sinusoidal wavy to analyze the peristaltic flow nature. We consider that the wavelength of the wall motion is much larger as compared to the channel width to validate the lubrication theory. To simplify the Poisson Boltzmann equation, we also use the Debye-Huckel linearization (i.e. wall zeta potential ≤ 25mV). We consider governing equation for micropolar fluid in absence of body force and couple effects however external electric field is employed. The solutions for axial velocity, spin velocity, flow rate, pressure rise and stream functions subjected to given physical boundary conditions are computed. The effects of pertinent parameters like Debye length and Helmholtz-Smoluchowski velocity which characterize the EDL phenomenon and external electric field, coupling number and micropolar parameter which characterize the micropolar fluid behavior, on peristaltic pumping are discussed through the illustrations. The results show that peristaltic pumping may alter by applying external electric fields. This model can be used to design and engineer the peristalsis-lab-on-chip and micro peristaltic syringe pumps for biomedical applications.

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Electroosmotic flow of biorheological micropolar fluids through microfluidic channels

Analytical solutions are developed for the electro-kinetic flow of a viscoelastic biological liquid in a finite length cylindrical capillary geometry under peristaltic waves. The Jefferys' non-Newtonian constitutive model is employed to characterize rheological properties of the fluid. The unsteady conservation equations for mass and momentum with electro-kinetic and Darcian porous medium drag force terms are reduced to a system of steady linearized conservation equations in an axisymmetric coordinate system. The long wavelength, creeping (low Reynolds number) and Debye-Huckel linearization approximations are utilized. The resulting boundary value problem is shown to be controlled by a number of parameters including the electro-osmotic parameter, Helmholtz-Smoluchowski velocity (maximum electro-osmotic velocity), and Jefferys' first parameter (ratio of relaxation and retardation time), wave amplitude. The influence of these parameters and also time on axial velocity, pressure difference, maximum volumetric flow rate and streamline distributions (for elucidating trapping phenomena) is visualized graphically and interpreted in detail. Pressure difference magnitudes are enhanced consistently with both increasing electro-osmotic parameter and Helmholtz-Smoluchowski velocity, whereas they are only elevated with increasing Jefferys' first parameter for positive volumetric flow rates. Maximum time averaged flow rate is enhanced with increasing electro-osmotic parameter, Helmholtz-Smoluchowski velocity and Jefferys' first parameter. Axial flow is accelerated in the core (plug) region of the conduit with greater values of electro-osmotic parameter and Helmholtz-Smoluchowski velocity whereas it is significantly decelerated with increasing Jefferys' first parameter. The simulations find applications in electro-osmotic (EO) transport processes in capillary physiology and also bio-inspired EO pump devices in chemical and aerospace engineering.

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Electro-kinetically driven peristaltic transport of viscoelastic physiological fluids through a finite length capillary: Mathematical modeling

The hydrodynamic dispersion of a solute in peristaltic flow of a reactive incompressible micropolar biofluid is studied as a model of chyme transport in the human intestinal system with wall effects. The long wavelength approximation, Taylor's limiting condition and dynamic boundary conditions at the flexible walls are used to obtain the average effective dispersion coefficient in the presence of combined homogeneous and heterogeneous chemical reactions. The effects of various pertinent parameters on the effective dispersion coefficient are discussed. It is observed that average effective dispersion coefficient increases with amplitude ratio which implies that dispersion is enhanced in the presence of peristalsis. Furthermore average effective dispersion coefficient is also elevated with the micropolar rheological and wall parameters. Conversely dispersion is found to decrease with cross viscosity coefficient, homogeneous and heterogeneous chemical reaction rates. The present simulations provide an important benchmark for future chemo-fluid-structure interaction computational models.

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Peristaltic flow and hydrodynamic dispersion of a reactive micropolar fluid-simulation of chemical effects in the digestive process

Mathematical Modelling Of Extraction Of The Underground Fluids: Application To Peristaltic Transportation Through A Vertical Conduit Occupied With Porous Material

Pulsatile flow of a dusty fluid thorough a constricted channel in the presence of magnetic field

Entropy generation is an important aspect of modern thermal polymer processing optimization. Many polymers exhibit strongly non-Newtonian effects and dissipation effects in thermal processing. Motivated by these aspects in this article a numerical analysis of the entropy generation with viscous dissipation effect in an unsteady flow of viscoelastic fluid from a vertical cylinder is presented. The Reiner-Rivlin physical model of grade two (second grade fluid) is employed which can envisage normal stress variations in polymeric flow-fields. Viscosity variation is included. The obtained governing equations are resolved using implicit finite difference method of Crank-Nicolson type with well imposed initial and boundary conditions. Key control parameters are the second-grade viscoelastic fluid parameter (β), viscosity variation parameter (γ) and viscous dissipation parameter (e). Also, group parameter (BrΩ-1), Grashof number (Gr) and Prandtl number (Pr) are examined. Numerical solutions are presented for steady-state flow variables, temperature, time histories of friction, wall heat transfer rate, entropy and Bejan curves for distinct values of control parameters. The results specify that entropy generation decreases with augmenting values of β, γ and Gr. The converse trend is noticed with increasing Pr and BrΩ-1. Furthermore, the computations reveal that entropy and Bejan lines only occur close to the hot cylinder wall.

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Computation of entropy generation in dissipative transient natural convective viscoelastic flow

In this paper, the influence of magnetic field on the dispersion of a solute in peristaltic flow of an incompressible micropolar fluid is studied as a model of fluid transport in the human intestinal system with wall properties. Long wavelength approximation, Taylor's limiting condition, and dynamic boundary conditions at the flexible walls are used to obtain the average effective dispersion coefficient in the presence of combined homogeneous and heterogeneous chemical reactions. The effects of various pertinent parameters on the effective dispersion coefficient are discussed. Average effective dispersion coefficient increases with amplitude ratio, which implies that dispersion is more in the presence of peristalsis. It also increases with the cross-viscosity coefficient, heterogeneous chemical reaction rate, and wall parameters. Further, dispersion decreases with micropolar parameter, magnetic parameter, and homogeneous chemical reaction rates. Copyright © 2015 John Wiley & Sons, Ltd.

G. Ravi Kiran

Papers

Peristaltic flow and hydrodynamic dispersion of a reactive micropolar fluid-simulation of chemical effects in the digestive process

Mathematical Modelling Of Extraction Of The Underground Fluids: Application To Peristaltic Transportation Through A Vertical Conduit Occupied With Porous Material

Pulsatile flow of a dusty fluid thorough a constricted channel in the presence of magnetic field

Computation of entropy generation in dissipative transient natural convective viscoelastic flow

Effect of homogeneous and heterogeneous chemical reactions on peristaltic transport of an MHD micropolar fluid with wall effects