Suspensions Of Particles In Fluid Research Articles

Heat and mass transfer of two-phase flow with Electric double layer effects induced due to peristaltic propulsion in the presence of transverse magnetic field

Abstract Biologically-inspired propulsion systems are currently receiving significant interest in the engineering applications. Motivated by these developments, in the present article analysed heat and mass transfer with the transverse magnetic field on peristaltic motion of two-phase flow (particle-fluid suspension) through a planar channel have been examined. The flow is observed under the influence of electric field and chemical reaction. The present flow problem is modeled using lubrication theory approximation and also with a combination of long wavelength and creeping flow regime assumptions. Moreover, the problem is further simplified using Debye linearization. Analytical solutions are obtained for the resulting coupled ordinary differential equations. The influence of various emerging parameters is discussed for velocity, temperature and concentration profile. Furthermore, the behavior of pressure rise is also discussed to analyse the pumping characteristics. Trapping mechanism is also presented with the help of streamlines. It is observed that velocity distribution tends to increase significantly due to the greater effect of electric field and electro-osmotic parameter, however, magnetic field and particle volume fraction provides a marked resistance to the flow. The influence of electric field and electro-osmotic parameter depicts converse behavior on temperature and concentration distribution. Furthermore, chemical reaction parameter causes a significant reduction in the concentration distribution. The main motivation of the present study is due to such fact that two-phase flow process is very important to analyse the peristaltic muscular expansion and contraction in propagating various biological fluids that act like a particle-fluid mixture. The present study has a wide range of applications in bio-medical engineering i.e. electromagnetic peristaltic micro pumps.

Unsteady Boundary Layer Flow and Convective Heat Transfer of a Fluid Particle Suspension with Nanoparticles over a Stretching Surface

AbstractWe analyzed the effects of Biot number and non-uniform heat source/sink on boundary layer flow and nonlinear radiative heat transfer of fluid particle suspension over an unsteady stretching surface embedded in a porous medium with nanoparticles. We considered conducting dust particles embedded with -water nanopartcles. The governing equations are transformed into nonlinear ordinary differential equations by using local similarity transformations and solved numerically using Runge–Kutta-Fehlberg-45 order method along with shooting technique. The effects of non-dimensional parameters on velocity and temperature profiles for fluid phase and dust phase are discussed and presented through graphs. Also, friction factor and Nusselt number are discussed and presented through graphs. Comparisons of the present study were made with existing studies under some special assumptions. The present results have an excellent agreement with existing studies. Results indicated that the enhancement in fluid particle interaction parameter increases the heat transfer rate and depreciates the wall friction. Also, radiation parameter has the tendency to increase the temperature profiles of the dusty nanofluid.

Radiative heat transfers of Carreau fluid flow over a stretching sheet with fluid particle suspension and temperature jump

Abstract The current study is to deliberate the flow and heat transfer of a Carreau fluid over a stretching sheet with fluid particle suspension. The temperature jump is also taken into account. The standard nonlinear system is resolved numerically via Runge-Kutta based shooting scheme. Role of substantial parameters on flow fields as well as on the fiction factor and heat transportation rates are determined and conferred in depth through graphs. It’s found that the velocity profile decreases and temperature profile increases, with an increasing the values of Weissenberg parameter. Further, the higher thermal slip parameter reduces the thermal boundary layer thickness. The thermal boundary layer thickness of fluid and dust particles decreases with the rise in Prandtl number.

Melting heat transfer of hyperbolic tangent fluid over a stretching sheet with fluid particle suspension and thermal radiation

The current investigation deals with melting heat transport in hyperbolic tangent fluid past a stretching sheet with fluid particle suspension and thermal radiation. Numerical solution is obtained via shooting technique after the applying of similarity variables to the governing partial equations. The effects of key parameters like magnetic parameter, fluid particle interaction parameter, Eckert number, Prandtl number, Weissenberg number and melting parameter are analyzed and discussed in detail with help of graphs and tables. Finally, the numerical values of the friction co-efficient and local Nusselt number are tabulated. Checked our results with existing work found excellent agreement. Results reveals that in the presence of melting parameter, the higher values of $W_e$ and $n$ depreciates the rate of heat transfer.

Non linear thermal radiation effect on Williamson fluid with particle-liquid suspension past a stretching surface

A mathematical analysis of two-phase boundary layer flow and heat transfer of a Williamson fluid with fluid particle suspension over a stretching sheet has been carried out in this paper. The region of temperature jump and nonlinear thermal radiation is considered in the energy transfer process. The principal equations of boundary layer flow and temperature transmission are reformed to a set of non-linear ordinary differential equations under suitable similarity transformations. The transfigured equalities are solved numerically with the help of RKF-45 order method. The effect of influencing parameters on velocity and temperature transfer of fluid is examined and deliberated by plotted graphs and tabulated values. Significances of the mass concentration of dust particle parameter play a key role in controlling flow and thermal behavior of non-Newtonian fluids. Further, the temperature and concern boundary layer girth are declines for increasing values of Williamson parameter.

Heat Transfer in a Loop Heat Pipe Using Fe2NiO4-H2O Nanofluid

Nanofluids are stable suspensions of nano fibers and particles in fluids. Recent investigations show that thermal behavior of these fluids, such as improved thermal conductivity and convection coefficients are superior to those of pure fluid or fluid suspension containing larger size particles. The use of enhanced thermal properties of nanofluids in a loop heat pipe (LHP) for the cooling of computer microchips is the main aim of this study. Thus, the Fe 2 NiO 4 -H 2 O served as the working fluid with nanoparticle mass concentrations ranged from 0 to 3 % in LHP for the heat input range from 20W to 60W was employed. Experimental apparatus and procedures were designed and implemented for measurements of the surface temperature of LHP. Then, a commercial liquid cooling kit of LHP system similar as used in experimental study was installed in real desktop PC CPU cooling system. The test results of the proposed system indicate that the average decrease of 5.75oC (14%) was achieved in core temperatures of desktop PC CPU charged with Fe 2 NiO 4 -H 2 O as compared with pure water under the same operating conditions. The results from this study should find it’s used in many industrial processes in which the knowledge on the heat transfer behavior in nanofluids charged LHP is of uttermost importance.

Steady-shear rheological properties for suspensions of axisymmetric particles in second-order fluids

Following Leal who gave the motion of a slender axisymmetric rod in a second-order fluid, we derived a complete rheological constitutive equation for dilute and semidilute slender rod suspensions in a viscoelastic solvent based on a cell model. Numerical solutions for the Fokker–Planck equation are obtained for simple shear flows at low and large Peclet numbers using a finite volume method, hence avoiding the need for closure approximations. The second normal stress difference coefficient of the solvent plays a non-negligible role in the particle contribution to the stress as well as on the rod orientation dynamics: a spread of the particle orientation in the flow-vorticity plane and an enhancement of the alignment along the vorticity direction are predicted when increasing the second normal stress difference coefficient. Brunn extended the Leal analysis to dumbbells and tri-dumbbells, for which both normal stress difference coefficients have to be considered. The original Pipkin diagram is finally modified to help guide the choice of relevant constitutive equations for particles in viscoelastic fluids.

Particulate suspension slip flow induced by peristaltic waves in a rectangular duct: Effect of lateral walls

This paper looks at the influence of lateral walls on peristaltic transport of a particle fluid suspension model applied in a non-uniform rectangular duct with slip boundaries. The peristaltic waves propagate on the horizontal sidewalls of a rectangular duct. The flow analysis has been developed for low Reynolds number and long wavelength approximation. Exact solutions have been established for the axial velocity and stream function. The effects of aspect the ratio β (ratio of height to width) and the volume fraction density of the particles C on the pumping characteristics are discussed in detail. The expressions for the pressure rise and friction forces on the wall of a rectangular duct were computed numerically and were plotted with variation of the flow rate for different values of the parameters. It is observed that in the peristaltic pumping (Δp>0,Q>0) and retrograde pumping (Δp>0,Q<0) regions the pumping rate increases with an increase in M, while in the copumping region (Δp<0,Q>0) the behavior is quite opposite. Furthermore it is also observed that the pressure rise increases in the upper half of the channel and decreases in the lower half of the channel with the increase in lslip parameter.

Study of variable magnetic field and endoscope on peristaltic blood flow of particle-fluid suspension through an annulus

Purpose In this article, the effects of variable magnetic field and endoscope on peristaltic motion of non-Newtonian blood flow of particle-fluid suspension through an annulus have been studied. The non-uniform annulus having incompressible, irrotational and electrically conducting fluid which is filled with rigid particles of different shapes. An assumption of long wavelength and zero Reynolds number approximation is applied to model the governing flow problem. A sinusoidal wave is traveling on the outer tube whereas the inner tube is considered as rigid and moving with a constant velocity.

THE INFLUENCE OF SELECTED FACTORS ON AXIAL FORCE AND FRICTION TORQUE IN A THRUST BEARING LUBRICATED WITH MAGNETORHEOLOGICAL FLUID

Magnetic fluids belong to the class of materials in which rheological properties can be controlled by magnetic fields. Magnetic fluids are suspensions of ferromagnetic particles in a carrier fluid, and the magnetic field can change their internal structure. This phenomenon is fully reversible, almost instantaneously. The test results of a hydrostatic bearing lubricated by magnetic fluid are shown in the publication [L. 7]. It has been shown that the use of MR fluids as a lubricant allows high stiffness of the bearing to be obtained regardless of the height of the bearing gap. The publication [L. 8] presents the results of a thrust bearing lubricated by magnetic fluid with no external feed pump. The load capacity of the bearing was achieved by a self-sealing effect. This effect is associated with the ability to hold a magnetic fluid in a predetermined position through the magnetic field. This is caused by the appropriate geometry of the bearing surface. This effect retains the flow of the magnetic fluid out of the bearing gap as a result of the occurrence of a magnetic barrier, which counteracts the movement of the magnetic fluid. This barrier is a result of a local increase or decrease in magnetic induction similar to magnetic fluid seals. Another phenomenon highlighted in [L. 9, 10, 11] is the generation in the magnetic fluid of additional pressure due to the interaction of the magnetic field gradient. The result is an additional buoyancy force. When selecting a magnetic fluid for application in the thrust bearing, a number of factors should be taken into account. In addition to the parameters describing the typical lubricant, such as lubricity, corrosion properties, and work at high temperatures, the magnetic fluid used in the friction zone should allow a wide range of the rheological properties to be obtained due to changes in the magnetic field intensity. It is also important that the magnetic fluids have the ability to generate the appropriate value of the normal force due to the magnetic field.

Heat transfer analysis on peristaltically induced motion of particle-fluid suspension with variable viscosity: Clot blood model

In this article, heat transfer analysis on clot blood model of the particle-fluid suspension through a non-uniform annulus has been investigated. The blood propagating along the whole length of the annulus was induced by peristaltic motion. The effects of variable viscosity and slip condition are also taken into account. The governing flow problem is modeled using lubrication approach by taking the assumption of long wavelength and creeping flow regime. The resulting equation for fluid phase and particle phase is solved analytically and closed form solutions are obtained. The physical impact of all the emerging parameters is discussed mathematically and graphically. Particularly, we considered the effects of particle volume fraction, slip parameter, the maximum height of clot, viscosity parameter, average volume flow rate, Prandtl number, Eckert number and fluid parameter on temperature profile, pressure rise and friction forces for outer and inner tube. Numerical computations have been used to determine the behavior of pressure rise and friction along the whole length of the annulus. The present study is also presented for an endoscope as a special case of our study. It is observed that greater influence of clot tends to rise the pressure rise significantly. It is also found that temperature profile increases due to the enhancement in Prandtl number, Eckert number, and fluid parameter. The present study reveals that friction forces for outer tube have higher magnitude as compared to the friction forces for an inner tube. In fact, the results for present study can also be reduced to the Newtonian fluid by taking ζ → ∞.

Particulate suspension Jeffrey fluid flow in a stenosed artery with a particle-free plasma layer near the wall

The present article concerns the problem of blood flow through an artery with an axially asymmetric stenosis (constriction). The two-layered macroscopic model consisting of a cell-rich core of suspension of all the erythrocytes described as a particle-fluid suspension (Jeffrey fluid) and a peripheral zone of cell-free plasma (Newtonian fluid). The analytical expressions for flow characteristics such as fluid phase and particle phase velocities, flow rate, wall shear stress, and resistive force are obtained. It is of interest to mention that the magnitudes of wall shear stress and flow resistance increase with red cell concentration but the flow resistance decreases with increasing shape parameter. One of the important observations is that when blood behaves like a Jeffrey fluid, the flowing blood experiences lesser wall shear stress and flow resistance than in the case of blood being characterized as a Newtonian fluid in both the particle-fluid suspension and particle- free flow studies. The rheology of blood as Jeffrey fluid and the introduction of plasma layer thickness cause significant reduction in the magnitudes of the flow characteristics.

Influence of magnetohydrodynamics on metachronal wave of particle-fluid suspension due to cilia motion

In this article, the influence of magnetohydrodynamics (MHD) on cilia motion of particle–fluid suspension through a porous planar channel has been investigated. The governing equations of Casson fluid model for fluid phase and particulate phase are solved by taking the assumption of long wavelength and neglecting the inertial forces due to laminar flow. The solutions for the resulting differential equations have been obtained analytically and a close form of solutions is presented. The expression for pressure rise along the whole length of the channel is evaluated numerically. The influences of all the physical parameters are demonstrated graphically. Trapping mechanism has also been discussed with the help of streamlines. It is observed that due to the influence of magnetohydrodynamics and particle volume fraction, velocity of the fluid decreases. It is also found that pressure rise shows similar behaviour for particle volume fraction and Casson fluid parameter.

Mixed convection two-phase flow of Maxwell fluid under the influence of non-linear thermal radiation, non-uniform heat source/sink and fluid-particle suspension

Abstract A detailed investigation of two-dimensional mixed convection flow of non-Newtonian fluid due to convectively heated stretching sheet in the presence of dust particles is conducted. The influence of viscous dissipation, nonlinear thermal radiation and non-uniform heat source/sink is considered in the heat transport equation. To simulate the nonlinear thermal radiation effect, the Rosseland approximation has been used. The governing equations are transformed into a set of self-similar nonlinear ordinary differential equations by means of suitable similarity transformations, which are then solved numerically by using Shooting method. The influence of pertinent parameters on the velocity and temperature distributions of both fluid and particle phases inside the boundary layer is observed and discussed in detail. Further, the features of skin friction coefficient and Nusselt number for different values of the governing parameters are also analysed and discussed. Moreover, the numerical results of present study and those existing ones are tabulated for some limiting case.

Macroscopic rheological behavior of suspensions of soft solid particles in yield stress fluids

In this study, we present a homogenization model for the macroscopic rheological behavior of non-colloidal suspensions of initially spherical, viscoelastic particles in yield stress fluids, which are subjected to uniform flow conditions. The constitutive behavior of the suspending fluid is characterized by the Herschel–Bulkley (HB) model, and the particles are assumed to be neutrally buoyant solids characterized by the finite-strain Kelvin–Voigt viscoelastic model. We make use of the “linear comparison composite” variational technique of Ponte Castañeda (1991) to approximate the instantaneous response of the suspensions of viscoelastic particles in the HB fluid by that of a fictitious suspension consisting of the same particles distributed identically in a Newtonian fluid with a suitably-chosen viscosity. The response of the latter suspension is then estimated by the homogenization model recently developed by Avazmohammadi and Ponte Castañeda (2015), which, when combined with appropriate evolution laws for the relevant microstructural variables, provides a complete characterization of the time-dependent response of the actual suspensions. With the objective of illustrating the key features of our model, we consider the particular case of suspensions of elastic particles in HB fluids under shear flow conditions. The results provide a broad picture of the influence of the HB fluid and particle constitutive properties, as well as of the particle volume fraction on the effective time-dependent and steady-state behaviors of the suspensions. For the special case of non-deformable particles, our model predicts that the suspensions behave like HB fluids with modified properties, consistent with the results of Chateau et al. (2008).

Slip effects and endoscopy analysis on blood flow of particle-fluid suspension induced by peristaltic wave

This study describes the endoscopy and slip effects on blood flow of particulate fluid suspension induced by peristaltic wave through a non-uniform annulus. An approximation of long wavelength and low Reynolds is used to model the governing equation of continuity and momentum equation for fluid phase and particulate phase. The influence of all the pertinent parameters has been obtained such as slip parameter (β), Jeffrey fluid parameter (λ1), particle volume fraction (C) and volume flow rate Q(z,t), velocity constant (v0) and the inner radius (ϵ) against pressure gradient, pressure rise, friction forces, velocity of fluid phase and particulate phase (uf,up). Numerical results are carried out for pressure rise and friction forces on the inner and outer tube.

Experimental Investigation of Al2O3-Polyethylene Glycol and TiO2-Polyethylene Glycol Nanofluids Flow through a Minichannel Heat Sink

Heat dissipation becomes a significant issue in the performance of various heat transfer systems. Thermal properties of liquids decide its heat transfer performance. Conventional fluids have inherently poor thermal conductivity which makes them not suitable for high heat loads and heat fluxes. Nanofluids are proposed as a promising challenger for advanced heat transfer fluids in a variety of engineering applications. Nanofluids are colloidal suspensions of nanometer-sized particles in various base fluids. Nanoparticles will improve the heat transfer characteristics of the base fluids effectively. In the present work, the forced convective heat transfer performance of copper mini channel heat sink has been carried out experimentally using Al2O3 polyethylene glycol and TiO2 polyethylene glycol nanofluids. The Al2O3 and TiO2 are converted into nanoparticles by using planetary ball mill and its shape was analysed. The nano particles then dispersed in polyethylene glycol base fluid by using a magnetic stirrer to form nano fluid for different volume concentration 0.5%, 1%, 1.5%, 2%, 2.5% without adding surfactant. The thermo physical properties thermal conductivity, density, viscosity, boiling point, flash and fire point, pH value, the heat transfer rate, heat transfer coefficient, heat flux of Al2O3 polyethylene glycol and TiO2 polyethylene glycol based nanofluids is evaluated. The comparative heat transfer performance of these two types of nanofluids for different volume concentration is analysed by passing it at a constant inlet velocity of 0.058m/s through a square shape copper mini channel heat sink (30x30mm) with seven passages by maintaining at constant heat supply. Further by varying the heat input of the minichannel heat sink the heat transfer phenomenon of these two types of nanofluid is analysed. The experimental evaluation conform the effective enhancement of heat transfer characteristics in nanofluid by the influence of volume concentration. The results showed that the Al2O3 polyethylene glycol nanofluid thermal performance increased significantly and out performs the TiO2 polyethylene glycol nanofluid. The highest improvement in the heat transfer occurred was 26% for 2.5 volume% Al2O3 polyethylene glycol nanofluid when compared to TiO2 polyethylene glycol nanofluid.

Effects of diffusion-thermo and thermo-diffusion on two-phase boundary layer flow past a stretching sheet with fluid-particle suspension and chemical reaction: A numerical study

A numerical investigation on laminar boundary layer flow, heat and mass transfer of two-phase particulate suspension induced by a linearly stretching sheet is carried out. In the mathematical formulation both the fluid and particle phases are treated as two separate interacting continua. The effects of magnetic field, diffusion-thermo, thermal-diffusion, thermal radiation and first order chemical reaction are taken into the account. The relevant governing partial differential equations corresponding to the momentum, energy and concentration are transformed into a system of non-linear ordinary differential equations with the help of appropriate similarity transformations and then solved numerically using Runge–Kutta-Fehlberg fourth fifth order method along with shooting scheme. The effects of the relevant physical parameters on the flow, heat and mass transfer characteristics of both fluid and particle phases were numerically obtained and discussed in detail. It is found that, the momentum, thermal and solute boundary layer thickness decreases with increasing the particles loading.

Flows of suspensions of particles in yield stress fluids

We study the rheological behavior of suspensions of noncolloidal spheres in yield stress fluids (concentrated emulsions). These are good model systems for understanding, e.g., the rheology of fresh concrete or debris flows, and more generally, the behavior of particles dispersed in any nonlinear material. We use magnetic resonance imaging techniques to investigate the flows of these yield stress suspensions in a concentric-cylinder Couette geometry. We extend the theoretical approach of Chateau et al. [J. Rheol. 52, 489–506 (2008)], valid for isotropic suspensions, to describe suspensions in simple shear flows, in which an anisotropic spatial distribution of particles is induced by flow. Theory and experiments show that the suspensions can be modeled by a Herschel–Bulkley behavior of same index as their interstitial fluid. We characterize the increase of their consistency and their yield stress with the particle volume fraction ϕ in the 0%–50% range. We observe a good agreement between the experimental va...

Simulations of the start-up of shear flow of 2D particle suspensions in viscoelastic fluids: Structure formation and rheology

We present simulations of the start-up of shear flow of 2D suspensions of rigid particles in viscoelastic fluids. A novel numerical method is applied that makes use of biperiodic domains, which act as representative volume elements of the suspension. Local mesh refinement ensures the method is both accurate and efficient, without the need for a repulsive potential between the particles. By averaging many simulations for random initial positions of the particles, we obtain the true rheological bulk response of the material. At Weissenberg numbers of 1 and higher, particle chaining is observed that leads to a decrease in bulk viscosity, an effect that was observed experimentally in Lyon et al. (2001). Increasing the solid area fraction leads to the particle alignment occurring faster and the particles forming longer chains, causing a stronger decrease in bulk viscosity. In addition, at solid area fractions of 0.3 and higher, an increase of the bulk first normal stress difference is observed, which may be attributed to an increase in local shear rate in between the particle chains. Finally, flow cessation is simulated and it is found that the particle chains are preserved until all elastic stresses in the fluid have relaxed.