Increasing Viscosity Parameter Research Articles

Flow and heat transportation in peristalsis of graphene-Fe 3 O 4 /H 2 O hybrid nanofluid with variable effective viscosity

Present communication addresses the flow and heat transportation for peristaltic transport of graphene-Fe 3 O 4/H 2 O hybrid nanofluid with irreversibility rate. Effects of variable viscosity, Hall current, Joule heating, porous medium and mixed convection are considered. A hybrid nanomaterial system is prepared by dispersing graphene and iron oxide nanomaterials with mass ratio (2:1) in an aqueous solution (water). Convective boundary conditions for temperature are also employed. The mathematical model is simplified by using lubrication theory. The obtained dimensionless model is then numerically solved. Results reveal that temperature of hybrid nanofluid reduces with an enhancement in volume fraction of graphene nanomaterials. Heat transfer rate at the right wall decays by increasing viscosity parameter. Velocity profile increases for larger permeability and Hall parameters. Presence of graphene nanomaterials decreases the pressure gradient. Entropy generation and Bejan numbers decrease by enhancing Biot number. The thermal efficiency of hybrid nanofluid (graphene-Fe 3 O 4/H 2 O) is more pronounced as compared to ordinary nanofluid (Fe 3 O 4/H 2 O) and base fluid (H 2 O). Additionally, comparison between NDSolve and numerical results achieved with bvp4c in MATLAB is also carried out to test our numerical codes.

MATHEMATICAL ANALYSIS OF VISCOSITY AND REABSORPTION ON URINE FLOW THROUGH A STRAIGHT NARROW TUBE

This study investigates the effect of variable viscosity (exponential and linear) and constant reabsorption for the urine flow through a narrow tube. The inertial free flow of viscous fluid has been governed by the momentum and mass conservation through the cross-section of axisymmetric tube. The governing partial differential equations have been simplified with the help of stream function and stress components with exponential and linear variable viscosity. The resulting partial differential equations have been solved by the inverse method and give the explicit expressions for velocity, pressure, shear stress, flux and leakage of flow. It has been observed that flow in transverse direction increases with the increase in reabsorption velocity at wall, whereas horizontal flow, shear stress and volume flow rate become slow with the increase in uniform reabsorption velocity. Effect of viscosity is significant near the walls of tube because the axial velocity accelerates by increasing viscosity parameter due to the pressure gradient near the center of tube but it decelerates near the walls of tube due to surface friction. Also, the special case of variable viscosity is discussed by assuming the linear type of viscosity. The derived data for the velocity and flow rate have been used to measure the fractional reabsorption in proximal tube with varying viscosity near the wall.

Lie similarity analysis of MHD flow past a stretching surface embedded in porous medium along with imposed heat source/sink and variable viscosity

The present examination is centered around the transfer of heat for the flow of a boundary layer free convective incompressible fluid, past a stretching porous surface, assuming viscosity dependent on temperature linearly along with heat source and sink with imposed magnetic field. Lie group similarity transformation is used to obtain the symmetric graphs of the given problem. Solutions for velocity and heat profile are encountered numerically with fourth-order Runga-Kutta shooting technique and graphically presented and explained the impact on velocity profile and temperature profile of several physical parameters as temperature-dependent parameter of viscosity A, k1 as parameter of permeability, Prandtl number, λas parameter of heat generation and absorption and M as parameter of magnetic field. We observed that the thermal boundary layer thickness can be reduced by increasing viscosity parameter A and heat sink parameterλ. As we give increment in k1 we find a decrement in the horizontal velocity profile, which leads to the enhanced deceleration of the flow and, hence, the velocity decreases.

The 2D Disk Structure with Advective Transonic Inflow–Outflow Solutions around Black Holes

Abstract We solved analytically viscous two-dimensional (2D) fluid equations for accretion and outflows in spherical polar coordinates (r, θ, ϕ) and obtained explicitly flow variables in r- and θ-directions around black holes (BHs). We investigated global transonic advection-dominated accretion flow (ADAF) solutions in an r-direction on an equatorial plane using Paczyński–Wiita potential. We used radial flow variables of ADAFs with symmetric conditions on the equatorial plane as initial values for integration in the θ-direction. In the study of 2D disk structure, we used two azimuthal components of viscous stress tensors—namely, and . Interestingly, we found that the whole advective disk does not participate in outflow generation, and the outflows form close to the BHs. Normally, outflow strength increased with increasing viscosity parameter (α 1), mass-loss parameter (s), and decreasing gas pressure ratio (β). The outflow region increased with increasing s, α 1 for and decreasing α 2 for . The is effective in angular momentum transportation at high latitude and outflows collimation along an axis of symmetry, since it changes polar velocity ( ) of the flow. The outflow emission is also affected by the ADAF size and decreases with it. Transonic surfaces formed for both inflows ( , very close to BH) and outflows ( ). We also explored no outflows, outflows, and failed outflows regions, which mainly depend on the viscosity parameters.

MHD oscillatory flow of a Jeffrey fluid in a vertical porous channel with viscous dissipation

Abstract The aim of this article is to investigate unsteady MHD convective flow in a vertical porous channel with viscous dissipation. The fluid is assumed to be non Newtonian, namely Jeffrey fluid and diffusion-thermo, thermal diffusion effect, suction are also taken into account. The governing coupled partial differential equations of the problem is reduced to ordinary differential equations and then solved by homotopy analysis method (HAM). The velocity, temperature and concentration fields are discussed with different values of involved parameter with the help of graphs. In addition, variations on coefficient of skin friction, heat and mass transfer coefficients are tabulated with different values of pertinent parameters. Comparison is made present solution (HAM) with numerical solution by using NDSolver in Mathematica. A suitable comparison has also been made as a limiting case of the considered problem. It is found that increasing magnetic parameter and suction parameter tends to suppress the fluid velocity while the reverse trend can be seen with material parameter. Thermal parameters are lead to enhance the fluid temperature whereas fluid temperature is decreasing function with increasing inertia coefficient. Volume flow rate decreases continuously with increasing suction parameter while it increases gradually with increasing viscosity parameter. Increasing Grashof number tends to enhance skin friction while increasing magnetic parameter leads to decrease the skin friction at the left wall. Further, increasing Soret number leads to suppress Sherwood number gradually at the left wall whereas mixed behavior can be noticed on Sherwood number distribution at the other wall.

Estimation of mass outflow rates from viscous relativistic accretion discs around black holes

We investigated flow in Schwarzschild metric, around a non-rotating black hole and obtained self-consistent accretion–ejection solution in full general relativity. We covered the whole of parameter space in the advective regime to obtain shocked, as well as, shock-free accretion solution. We computed the jet streamline using von Zeipel surfaces and projected the jet equations of motion on to the streamline and solved them simultaneously with the accretion disc equations of motion. We found that steady shock cannot exist beyond α ≳ 0.06 in the general relativistic prescription, but is lower if mass-loss is considered too. We showed that for fixed outer boundary, the shock moves closer to the horizon with increasing viscosity parameter. The mass outflow rate increases as the shock moves closer to the black hole, but eventually decreases, maximizing at some intermediate value of shock location. The jet terminal speed increases with stronger shocks; quantitatively speaking, the terminal speed of jets vj∞ > 0.1 if rsh < 20rg. The maximum of the outflow rate obtained in the general relativistic regime is less than 6 per cent of the mass accretion rate.

Thermal Convection in a Nanofluid Layer with Thermorheological Effect

Thermorheological effect on the onset of convection in a horizontal nanofluid layer heated from below is studied for rigid-rigid, free-free and rigid-free boundaries by incorporating the effects of Brownian motion and thermophoresis. The viscosity of nanofluid is allowed to vary exponentially with temperature. The boundaries are considered to be isothermal and the normal flux of nanoparticle volume fraction is taken to be zero on the boundaries. The resulting eigenvalue problem is solved numerically by the Galerkin method and observed that the instability sets in only as stationary convection irrespective of the velocity boundary conditions. The stability characteristics of the system are strongly dependent on the viscosity parameter. At low values of the viscosity parameter, the variation in the critical Rayleigh number is found to be nominal but increases with increasing viscosity parameter, reaches a maximum and then decreases. Results also indicate that increase in the modified diffusivity ratio, concentration Rayleigh number, and Lewis number is to hasten the convection while the modified particle density increment has no observable effect on the onset of convection.

Viscosity and Temperature Influences on PLIF

This paper describes the tests of accuracy in order to adapt Planar Laser Induced Fluorescence (PLIF) to various viscous fluids. It describes the influence of increasing viscosity parameter on fluorescence intensity in case of using Rhodamine B dye and Argon-ion laser illumination. It allows concluding what are the influences of the tested illumination laser intensity, Rhodamine B dye concentration levels, temperature and viscosity on fluoresced intensity. The different tests allow separation of influence of the above cited parameters. Temperature is controlled and modified with the help of a water bath whereas mixtures were enclosed in 3.5ml glass cells.

Entropy analysis for third grade fluid flow with Vogel model viscosity in annular pipe

The steady-state flow of a third grade fluid between concentric circular cylinders is considered and entropy generation due to fluid friction and heat transfer in the annular pipe is examined. Depending upon the fluid viscosity, entropy generation in the flow system varies. The third grade fluid is employed to account for the non-Newtonian effect while Vogel model is accommodated for temperature-dependent viscosity. The analysis is based on perturbation technique. The closed form solutions for velocity, temperature and entropy fields are presented. Entropy generation due to fluid friction and heat transfer in the flow system is formulated. The influence of viscosity parameters A and B on the entropy generation number is investigated. It is found that entropy generation number reduces with increasing viscosity parameter A , which is more pronounced in the region close to the annular pipe inner wall and opposite is true for increasing viscosity parameter B .

Entropy generation for pipe flow of a third grade fluid with Vogel model viscosity

The flow of fluid–solid mixtures in a pipe can be treated as non-Newtonian fluids of third grade. Depending upon the fluid viscosity, entropy generation in the flow system varies. In the present study, flow of third grade fluid in a pipe is considered. The Vogel model is introduced to account for the temperature-dependent viscosity. Entropy generation due to fluid friction and heat transfer in the flow system is formulated. The influence of viscosity parameters A and B on the entropy generation number is investigated. It is found that increasing viscosity parameter A reduces the entropy generation number and opposite is true for increasing viscosity parameter B.

Effects of an endoscope and fluid with variable viscosity on peristaltic motion

The influence of an inserted endoscope and fluid with variable viscosity on the peristaltic motion has been investigated under zero Reynolds number. The problem is formulated using a perturbation expansion in terms of a variant wave number. The effects of curvature, viscosity, radius of an endoscope and amplitude of the wave on the pressure rise and friction forces on the inner and outer tubes are analyzed. Peristaltic and augmented pumping are discussed. The results show that, the pressure rise increases with increasing wave number, amplitude ratio and radius ratio. Also, it decreases with increasing viscosity parameter. Further, it is independent of wave number, amplitude ratio, radius ratio and viscosity parameter at certain values of flow rate. A comparison with previous studies is given.