Effect of body acceleration on pulsatile flow of Casson fluid through a mild stenosed artery

Nagarani, P.,Sarojamma, G. The Korean Society of Rheology 2008 Korea-Australia rheology journal Vol.20 No.4

The pulsatile flow of blood through a stenosed artery under the influence of external periodic body acceleration is studied. The effect of non-Newtonian nature of blood in small blood vessels has been taken into account by modeling blood as a Casson fluid. The non-linear coupled equations governing the flow are solved using perturbation analysis assuming that the Womersley frequency parameter is small which is valid for physiological situations in small blood vessels. The effect of pulsatility, stenosis, body acceleration, yield stress of the fluid and pressure gradient on the yield plane locations, velocity distribution, flow rate, shear stress and frictional resistance are investigated. It is noticed that the effect of yield stress and stenosis is to reduce flow rate and increase flow resistance. The impact of body acceleration is to enhance the flow rate and reduces resistance to flow.

EFFECT OF FLOW UNSTEADINESS ON DISPERSION IN NON-NEWTONIAN FLUID IN AN ANNULUS

NAGARANI, P.,SEBASTIAN, B.T. The Korean Society for Computational and Applied M 2017 Journal of applied mathematics & informatics Vol.35 No.3

An analysis is made to study the solute transport in a Casson fluid flow through an annulus in presence of oscillatory flow field and determine how this flow influence the solute dispersion along the annular region. Axial dispersion coefficient and the mean concentration expressions are calculated using the generalized dispersion model. Dispersion coefficient in oscillatory flow is found to be a function of frequency parameter, Schmidt number, and the pressure fluctuation component besides its dependency on yield stress of the fluid, annular gap and time in the case of steady flow. Due to the oscillatory nature of the flow, the dispersion coefficient changes cyclically and the amplitude and magnitude of the dispersion increases initially with time and reaches a non - transient state after a certain critical time. This critical value varies with frequency parameter and independent of the other parameters. It is found that the presence of inner cylinder and increase in the size of the inner cylinder inhibits the dispersion process. This model may be used in understanding the dispersion phenomenon in cardiovascular flows and in particular in catheterized arteries.

Peristaltic flow of a Casson fluid in an annulus

Nagarani, P.,Lewis, A. 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1

Peristaltic transport of a non-Newtonian fluid through the annular gap between two coaxial tubes is studied. We assumed that the inner tube is rigid whereas the outer tube has sinusoidal wave travelling down its wall. We modelled the flowing fluid as a Casson fluid to study the combined effects of yield stress (plug width) and annular gap on peristaltic transport. The flow is investigated in a wave frame of reference moving with velocity of the wave under long wavelength and low Reynolds number assumption. The expressions for velocity, stream function, pressure rise, flow rate and frictional force on inner and outer wall are obtained. Results are shown graphically and discussed in the results and discussion section. It is observed that yield stress and annular gap both have significant impact on the pressure rise, frictional resistance on the walls and on the formation and variation of trapped bolus.

Peristaltic flow of a Casson fluid in an annulus

P. Nagarani,A. Lewis 한국유변학회 2012 Korea-Australia rheology journal Vol.24 No.1

Peristaltic transport of a non-Newtonian fluid through the annular gap between two coaxial tubes is studied. We assumed that the inner tube is rigid whereas the outer tube has sinusoidal wave travelling down its wall. We modelled the flowing fluid as a Casson fluid to study the combined effects of yield stress (plug width) and annular gap on peristaltic transport. The flow is investigated in a wave frame of reference moving with velocity of the wave under long wavelength and low Reynolds number assumption. The expressions for velocity, stream function, pressure rise, flow rate and frictional force on inner and outer wall are obtained. Results are shown graphically and discussed in the results and discussion section. It is observed that yield stress and annular gap both have significant impact on the pressure rise, frictional resistance on the walls and on the formation and variation of trapped bolus.

Peristaltic transport of a Casson fluid in an inclined channel

P. Nagarani 한국유변학회 2010 Korea-Australia rheology journal Vol.22 No.2

Peristaltic transport of a Casson fluid in an inclined channel is analyzed under long wavelength and low Reynolds number assumptions. The flow is investigated in a wave frame of reference moving with velocity of the wave. The expressions for velocity, stream function, pressure rise, flow rate and flow resistance are obtained. The combined e, flow f plug width and angl combinclination on pumping characteristics, frictional fteri on wall and trapping phenomenon is discussed. Iowis o on wallthat the angl combinclination and plug width of the fluid Tow pressure risimpact on pressure rise, frictional force and formation of trapped bolus. It is also observed that the effect of frictional force with respect to each parameter is similar but in converse to the case of pressure rise distribution.

Effect of body acceleration on pulsatile flow of Casson fluid through a mild stenosed artery

P. Nagarani,G. Sarojamma 한국유변학회 2008 Korea-Australia rheology journal Vol.20 No.4

The pulsatile flow of blood through a stenosed artery under the influence of external periodic body acceleration is studied. The effect of non-Newtonian nature of blood in small blood vessels has been taken into account by modeling blood as a Casson fluid. The non-linear coupled equations governing the flow are solved using perturbation analysis assuming that the Womersley frequency parameter is small which is valid for physiological situations in small blood vessels. The effect of pulsatility, stenosis, body acceleration, yield stress of the fluid and pressure gradient on the yield plane locations, velocity distribution, flow rate, shear stress and frictional resistance are investigated. It is noticed that the effect of yield stress and stenosis is to reduce flow rate and increase flow resistance. The impact of body acceleration is to enhance the flow rate and reduces resistance to flow.

EFFECT OF FLOW UNSTEADINESS ON DISPERSION IN NON-NEWTONIAN FLUID IN AN ANNULUS

P. Nagarani,B.T. Sebastian 한국전산응용수학회 2017 Journal of applied mathematics & informatics Vol.35 No.3

An analysis is made to study the solute transport in a Casson fluid flow through an annulus in presence of oscillatory flow field and determine how this flow influence the solute dispersion along the annular region. Axial dispersion coefficient and the mean concentration expressions are calculated using the generalized dispersion model. Dispersion coefficient in oscillatory flow is found to be a function of frequency parameter, Schmidt number, and the pressure fluctuation component besides its dependency on yield stress of the fluid, annular gap and time in the case of steady flow. Due to the oscillatory nature of the flow, the dispersion coefficient changes cyclically and the amplitude and magnitude of the dispersion increases initially with time and reaches a non - transient state after a certain critical time. This critical value varies with frequency parameter and independent of the other parameters. It is found that the presence of inner cylinder and increase in the size of the inner cylinder inhibits the dispersion process. This model may be used in understanding the dispersion phenomenon in cardiovascular flows and in particular in catheterized arteries.

Peristaltic pumping of an Ellis fluid in an inclined asymmetric channel

A. Small,P. Nagarani,M. Narahari 한국전산응용수학회 2023 Journal of applied mathematics & informatics Vol.41 No.1

The flow of an incompressible Ellis fluid in an inclined asymmetric channel, driven by peristaltic waves was studied under low Reynolds number and long wavelength assumptions. The wave on each side of the channel are assumed to be an infinite train of sinusoidal waves, both having the same constant wave speed and wavelength however, they vary in wave amplitude, channel half width and phase angle. We derived expressions for the axial and transverse velocities, volume flow rate, pressure rise per unit wavelength and streamlines. The effects of varying the wave amplitudes, the phase angle, the channel width, the angle of inclination of the channel as well as the fluid parameters on the flow were analyzed. Trapping conditions were determined and the presence of reflux highlighted using the streamlines for the necessary channel and fluid conditions. By varying the fluid parameters, changes in the fluid that deviated from the Newtonian case resulted in a reduction in the axial velocity in the neighborhood of the center of the channel and a simultaneous increase in the velocity at the periphery of the channel. A nonlinear relation was observed with the pressure rise and the volume flow rate. This nonlinear relation is more pronounced with an increase in the absolute value of the volume flow rate. For Newtonian fluids a linear relation exists between these two variables. The fluid parameters had little effects on the streamlines. However, variations of the wave amplitudes, volume flow, channel width and phase angle had greater effects on the streamlines and hence the trapped region.

Convection-diffusion in unsteady non-Newtonian fluid flow in an annulus with wall absorption

Binil Thomas Sebastian,P. Nagarani 한국유변학회 2018 Korea-Australia rheology journal Vol.30 No.4

The present study investigates the combined effects of non-Newtonian rheology and unsteady nature of the fluid on dispersion of a soluble substance between two coaxial cylinders having wall permeability at the outer wall with the flowing fluid is modelled as Casson fluid. Generalized dispersion method in combination with a finite difference scheme is used to study the dispersion phenomenon. Using the generalized dispersion model, the entire process of dispersion is expressed in terms of three transport coefficients viz., absorption, convection, and dispersion (effective diffusion) coefficients. These transport coefficients are evaluated numerically using Crank-Nicolson finite difference method. The mean concentration is expressed in terms of these transport coefficients. Effects of annular gap, yield stress, Womersley frequency parameter, amplitude of the pressure pulsation, and the absorption parameter on the transport coefficients and mean concentration are studied. Flow unsteadiness is observed influencing the dispersion coefficient both quantitatively and qualitatively. It is observed that, as Womersley number increases the fluctuation of the dispersion coefficient increases and the magnitude of dispersion coefficient decreases for small values of time (< 0.5) and increases for later values of time.