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Tripathi D.,National Institute of Technology Delhi | Beg O.A.,Gort Engovation Research Propulsion and Biomechanics
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine | Year: 2014

This article studies theoretically the transportation of rheological viscoplastic fluids through physiological vessels by continuous muscle contraction and relaxation, that is, peristalsis. Both cases of planar and cylindrical physiological vessels are considered. A mathematical model is developed under long wavelength and low Reynolds number approximations. Expressions for axial velocity in core region, axial velocity in plug flow region, volume flow rate and pressure gradient in non-dimensional form are obtained. A comparative study of velocity profiles, pressure distribution, friction force and mechanical efficiency for different viscoplastic liquids is conducted. The influence of width of plug flow region, shear rate strain index and yield stress index on the pressure distribution, friction force and mechanical efficiency is elaborated. The study is relevant to gastric fluid mechanics and also non-Newtonian biomimetic pump hazardous waste systems exploiting peristaltic mechanisms. © IMechE 2013. Source

Tripathi D.,National Institute of Technology Delhi | Pandey S.K.,Indian Institute of Technology BHU Varanasi | Beg O.A.,Gort Engovation Research Propulsion and Biomechanics
International Journal of Thermal Sciences | Year: 2013

The present paper describes a mathematical study on peristaltic flow of viscoelastic fluids (with the robust Jeffrey model) through a finite length channel under the influence of heat transfer. The study is motivated by the need to further elucidate the mechanisms inherent in swallowing of diverse food bolus types (bread, fruit jam and almost all edible semi-solids) through the oesophagus, by taking account of the viscous and elastic effects. The expressions for temperature field, axial velocity, transverse velocity, volume flow rate, pressure gradient, local wall shear stress, mechanical efficiency, stream function, and reflux limit are obtained, when the Reynolds number is small and the wavelength is large, by using appropriate analytical and numerical methods. The computational results are presented in graphical form. The influence of thermophysical (heat transfer), relaxation time and retardation time parameters on pressure distribution, local wall shear stress profiles, temperature profiles and velocity profiles are studied in detail. Furthermore we investigate the effects of these parameters on two inherent phenomena (reflux and trapping) characterizing peristaltic flow using streamline plots. The present study emphasizes an important observation, namely that pressure along the entire length of the channel reduces when the magnitude of relaxation time (retardation time is fixed) or Grashof number or indeed thermal conductivity increase, whereas pressure is enhanced by increasing the magnitude of retardation time (relaxation time is fixed). © 2013 Elsevier Masson SAS. All rights reserved. Source

Tripathi D.,National Institute of Technology Delhi | Beg O.A.,Gort Engovation Research Propulsion and Biomechanics
International Journal of Heat and Mass Transfer | Year: 2014

This paper studies the peristaltic flow of nanofluids through a two-dimensional channel. The analysis is conducted based on the long wavelength and low Reynolds number approximations. The walls of the channel surface propagate sinusoidally along the channel. The Buongiornio formulation for nanofluids is employed. Approximate analytical solutions for nanoparticle fraction field, temperature field, axial velocity, volume flow rate, pressure gradient and stream function are obtained. The impact of the pertinent physical parameters i.e. thermal Grashof number, basic-density Grashof number, Brownian motion parameter and thermophoresis parameter on nanoparticle fraction profile, temperature profile, velocity profile and trapping phenomenon are computed numerically. The results of this study demonstrate good correlation with the Newtonian results of Shapiro et al. (1969) [4], which is a special case (Gr T = 0, GrF = 0) of the generalized model developed in this article. Applications of the study include peristaltic micro-pumps and novel drug delivery systems in pharmacological engineering. © 2013 Elsevier Ltd. All rights reserved. Source

Uddin M.J.,Universiti Sains Malaysia | Yusoff N.H.M.,Universiti Sains Malaysia | Anwar Beg O.,Gort Engovation Research Propulsion and Biomechanics | Ismail A.I.,Universiti Sains Malaysia
Physica Scripta | Year: 2013

A mathematical model is presented and analysed for steady two-dimensional non-isothermal boundary layer flow from a heated horizontal surface which is embedded in a porous medium saturated with a non-Newtonian power-law nanofluid. It is assumed that the wall temperature and nanoparticle volume fraction vary nonlinearly with the axial distance. By applying appropriate group transformations, the governing transport equations are reduced to a system of coupled, nonlinear ordinary differential equations with associated boundary conditions. The reduced equations are then solved numerically using the Runge-Kutta-Fehlberg fourth-fifth-order numerical method with Maple 13 software. The effects of several thermophysical parameters including rheological power-law index, non-isothermal index, Lewis number, Brownian motion parameter, thermophoresis parameter, buoyancy ratio and internal heat generation/absorption parameter on the non-dimensional velocity, temperature, nanoparticle volume fraction (concentration) and also on the friction factor, heat and mass transfer rates are investigated. A comparison of the present results with the existing published results shows excellent agreement, verifying the accuracy of the present numerical code. The study finds applications in nano biopolymeric manufacturing processes and also thermal enhancement of energy systems employing rheological working fluids. © 2013 The Royal Swedish Academy of Sciences. Source

Rashidi M.M.,Bu - Ali Sina University | Freidoonimehr N.,Islamic Azad University | Hosseini A.,Bu - Ali Sina University | Beg O.A.,Gort Engovation Research Propulsion and Biomechanics | Hung T.-K.,University of Pittsburgh
Meccanica | Year: 2014

In this article we derive semi-analytical/numerical solutions for transport phenomena (momentum, heat and mass transfer) in a nanofluid regime adjacent to a nonlinearly porous stretching sheet by means of the Homotopy analysis method (HAM). The governing equations are reduced to a nonlinear, coupled, non-similar, ordinary differential equation system via appropriate similarity transformations. This system is solved under physically realistic boundary conditions to compute stream function, velocity, temperature and concentration function distributions. The results of the present study are compared with numerical quadrature solutions employing a shooting technique with excellent correlation. Furthermore the current HAM solutions demonstrate very good correlation with the non-transpiring finite element solutions of Rana and Bhargava (Commun. Nonlinear Sci. Numer. Simul. 17:212-226, 2012). The influence of stretching parameter, transpiration (wall suction/injection) Prandtl number, Brownian motion parameter, thermophoresis parameter and Lewis number on velocity, temperature and concentration functions is illustrated graphically. Transpiration is shown to exert a substantial influence on flow characteristics. Applications of the study include industrial nanotechnological fabrication processes. © 2013 Springer Science+Business Media Dordrecht. Source

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