Suspensions Of Particles In Fluid Research Articles

Comprehensive analysis of thermal radiation and viscous dissipation impacts on fluid-particle suspension of Rabinowitsch fluid through a uniform horizontal tube

Comprehensive analysis of thermal radiation and viscous dissipation impacts on fluid-particle suspension of Rabinowitsch fluid through a uniform horizontal tube

Stability of plane parallel flow revisited for particle-fluid suspensions

Abstract An alternative model is proposed for hydrodynamic stability of plane parallel flow of an incompressible Newtonian fluids with suspended solid particles. For heavy particle-laden dusty gases with negligible particle volume fraction, the effective complex-form mean velocity in the modified Orr-Sommerfeld equation derived by the present model is showed to be essentially identical to the well-known Saffman's classical results. In the limit cases of small or large Stokes number of particles, simple formulas are derived for the effective Reynolds number ratio of the particle-laden suspension to the clear fluid without particles under otherwise identical conditions. The derived formula for particles of finite particle-to-fluid density ratio and small Stokes number is verified by comparing predicted results with known data, although a comparison of the derived formula with known results for particles of finite density ratio and large Stokes number cannot be made here due to the lack of available data. It is hoped that the present work could offer a conceptually novel and relatively simplified model for hydrodynamics of solid particle-fluid suspensions.

Thermal transport characteristics of fluid-particle suspension in a vertical uniform tube: A computational study on Rabinowitsch fluid with uniform heat source

Problem statement The thermal transport of fluid-particle suspension in Rabinowitsch fluid is discussed theoretically in a vertical uniform tube under the consideration of a uniform heat source. Methodology The fluid and particle phase models are used to develop the mathematical model in the form of partial differential equations which are solved through the symbolic software MATHEMATICA version 12.0 and present the exact solution of temperature distribution, velocity of fluid and particle phases, wall shear stress, pressure gradient, pressure rise, and stream function, etc. Computational results and findings The volume fraction density of the particles slows down the motion of the fluid particles. The velocity of Newtonian fluid is maximum as compared to pseudo-plastic and Dilatant fluids. The fluid phase velocity is superior to particle phase velocity distribution for all pertinent parameters of the analysis. The pressure rise increases in the case of Newtonian and pseudo plastic fluid and decreases in Dilatant fluid. The trapping phenomena are strongly associated with the volume fraction density of the particle. The shear stress shows a decreasing trend against the volume fraction density of the particles, Grashoff number, and heat source parameter. Special case The current fluid model (Rabinowitsch fluid) can be reduced in Newtonian, pseudo plastic, and Dilatant fluid for taking κ → 0 , κ < 0 , and κ > 0 , respectively. Applications The current analysis can be useful in biomedical engineering to observe the blood supply through the arteries, the removal of kidney stones, and also the passage of urine to the bladder from the ureter. Originality The present research is original and has not been published before.

Grasping the behavior of magnetorheological fluids in gradient pinch mode via microscopic imaging

Magnetorheological (MR) fluids are suspensions of micrometer-sized ferromagnetic particles in a carrier fluid, which react to magnetic fields. The fluids can be operated in several fundamental modes. Contrary to the other modes, the rheology and microstructure formation of the MR fluid in the gradient pinch mode have been studied to a far lesser extent. The magnetic field distribution in the flow channel is intentionally made non-uniform. It is hypothesized that the Venturi-like contraction is achieved via fluid property changes, leading to a unique behavior and the presence of a pseudo-orifice. The main goal is to investigate the presence of the Venturi-like contraction effect in the fluid by means of optical imaging and hydraulic measurements. To accomplish the goal, a unique test rig has been developed including a fluorescence microscope and MR valve prototype. The Venturi-like contraction hypothesis was confirmed. The results indicate that the effective flow channel size decreases by 92% at the maximum magnetic flux applied. This has a direct impact on the flow characteristics of the MR valve. The variation of the pressure–flow rate curve slope with magnetic field was demonstrated. The results provide valuable information for understanding the rheology and microstructure formation mechanism in MR fluids in the pinch mode.

Significance of hafnium nanoparticles in hydromagnetic non-Newtonian fluid-particle suspension model through divergent channel with uniform heat source: thermal analysis

Abstract This theoretical analysis provided the exact solution of a steady flow of Casson rheological fluid in fluid-particle suspension models through a divergent channel with consideration of porous medium, electric, and magnetic fields, and slip boundary conditions. The thermal transport analysis is also observed with the consideration of viscous dissipation and uniform heat source. The suitable transformation is used to reduce the partial differential equation into ordinary differential equations and obtain the exact solution by adopting the mathematical software MATHEMATICA 12.0. The momentum and thermal profiles are decreasing functions of the magnetic field parameter. The number of streamlines is increased and covers more parts of the channel for increasing the Darcy force and velocity slip parameters. The computational results of this study will help to understand the momentum and thermal analysis in the fluid-particle suspension model. The results of the current study are useful to increase the oil recovery system, in thermal transport energy, energy production, cooling and heating systems, etc. The current model can be useful in renewable energy to store thermal energy by using the hafnium nanoparticles. The present analysis is original and has not been submitted nor published before.

Thermal transport analysis in hydromagnetic fluid-particle suspension model under the effect of slip boundary conditions and electric field: Applications in solar power plant

Thermal transport analysis in hydromagnetic fluid-particle suspension model under the effect of slip boundary conditions and electric field: Applications in solar power plant

Study the effect of cohesion on fine particle transportation through a pore doublet model: A CFD-DEM study

This research delves into the transportation of micro-sized particles within a doublet pore model featuring two distinct pore throat sizes. To simulate a two-phase particle-fluid suspension, the CFD-DEM method is employed, combining the Navier-Stokes equation with Newton's second law of particle motion. Cohesion forces between particles and pore throats are characterized using the Simplified Johnson-Kendall-Roberts (SJKR) contact model, which is applied in our simulation to identify locations of agglomerations. Results reveal that altering cohesive energy density, from 10,000 Jm3 to 100,000 Jm3, significantly increases the likelihood of agglomeration in the smaller pore throat. It becomes evident that areas in close proximity to the throats are the most prone to particle agglomerations, leading to pressure drops over time. The formation of particle clusters within the pore throats intensifies with both an increase in the number of particles and fluid velocity from 0.001ms to 0.01ms. Nevertheless, low flow rates (0.001ms) are insufficient to mitigate blockages.

Stokes’ Second Flow Problem Revisited for Particle–Fluid Suspensions

Abstract An alternative analytical model is proposed for hydrodynamics of incompressible Newtonian fluids with suspended solid particles. Unlike existing single-phase models that do not distinguish the velocity field of suspended particles from the velocity field of host fluid, the present model accounts for the relative shift between the two velocity fields and assumes that its effect can be largely captured by substituting the inertia term of Navier–Stokes equations with the acceleration field of the mass center of the representative unit cell. The proposed model enjoys a relatively concise mathematical formulation. The oscillating flow of a particle–fluid suspension between two flat plates is studied with the present model, and detailed results are presented for Stokes’ second flow problem on the oscillating flow of a suspension half-space induced by an oscillating plate with specific examples of dusty gases and nanofluids. Remarkably, leading-order asymptotic expressions derived by the present model, for the effect of suspended particles on the decay index and wavenumber of the velocity field, are shown to be identical to known results derived based on the widely adopted Saffman model for dusty gases. It is hoped that the present work could offer a relatively simplified and yet reasonably accurate model for hydrodynamic problems of particle–fluid suspensions.

A direct method for acoustic waves in hard particle–fluid suspensions

A direct method for acoustic waves in hard particle–fluid suspensions

Investigating the effect of different base fluids in atomic and thermal behaviors of different nano-refrigerants using molecular dynamics simulation

Nano-refrigerants, which are the suspensions of nano-sized particles in a base fluid, were applied in many devices and systems to enhance thermal conductivity and improve heat transfer performance. This work studied the thermal and atomic behavior of two kinds of nano-refrigerants located inside an aluminum nanochannel for 5 ns. The molecular dynamics (simulation method simulated Nano-refrigerants, including R-134a and R-407A as base fluids and copper as nanoparticles. The density, velocity, and temperature profiles were studied to investigate the atomic behavior of the simulated sample. The thermal behavior of structures was studied by examining the phase transition rate, phase change time, thermal conductivity, and heat flux. The results show that R-407A base fluid showed better thermal behavior. The results show that in Cu/R-407A, the phase-changed particle reached 31% in 5 ns, and phase change time was estimated to be 3.91 ns. In contrast, in Cu/R-134a, the samples' phase changed particle and phase change time reached 26% and 4.06 ns. Moreover, the study of heat flux shows that nano-refrigerant with R-407A base fluid had more HF (1028 W/m2) than R-134a (654 W/m2). The results show that the thermal conductivity of R-407A and R-134a nano-refrigerant converged to 0.0975 and 0.0098 W/mK, respectively.

Effect of Non-Linear Radiation and Non-Uniform Heat Source/Sink on Flow over a Linear Stretching Sheet with Fluid Particle Suspension

In this paper, the flow and heat transfer of dusty flow over a linear stretchable sheet has been analyzed. The effects of non-linear radiation and non-uniform heat source or sink have been studied. Considering the mentioned terms and conditions, the problem has been formulated. The formulation consists of systems of nonlinear PDEs which has been converted to a system of ODEs by taking suitable similarity transformations. Then the systems of ODEs have been solved by using Rungakutta method of 4th order. The computations work has been carried out by using BVP4C tool of MATLAB. The impact of flow parameters like radiation parameter, prandtl number, eckret number, fluid Particle interaction parameter β and diffusivity parameter on flow and heat transfer are investigated. The results are presented through graphs and tables. From the graphs, it is concluded that the presence of particles in fluid has some impact of different parameters in flow and heat transfer. The parameters like Eckert number, Fluid- particle interaction parameter, diffusivity parameter have remarkable effects of presence of particles

Rheological study of Hall current and slip boundary conditions on fluid-nanoparticle phases in a convergent channel.

Purpose: the purpose of this theoretical study was to analyze the heat transfer in the fluid-particle suspension model under the effects of a porous medium, magnetic field, Hall effects, and slip boundary conditions in a convergent channel with the addition of electrokinetic phenomena. The Darcy-Brinkman (non-Darcy porous medium) model was used to assess the effects of the porous medium. Methodology: the rheological equations of both models were transformed into a dimensionless form to obtain the exact solutions of the fluid and particle phase velocities, pressure gradient, volumetric flow rate, stream function, temperature distribution, and heat-transfer rate. To obtain an exact solution to the models, the physical aspects of the parameters are discussed, analyzed, and reported through graphs, contour plots, and in tabular form. Findings: mixing in hafnium particles in a viscous fluid provide 1.2% more cooling compared to with a regular fluid. A reduction of the streamlines was observed with the contribution of the slip condition. The utilization of the Darcy parameters upgraded both the fluid flow and temperature profiles, while the heat-transfer rate decreased by up to 3.3% and 1.7% with the addition of a magnetic field and porous medium, respectively. Originality: the current study is an original work of the authors and has not been submitted nor published elsewhere.

Inertial and Particle Shape Effects on Fluid-Particle Suspension Flows: A Resolved SPH-DEM Study

Inertial and Particle Shape Effects on Fluid-Particle Suspension Flows: A Resolved SPH-DEM Study

Can We Structure Biomaterials to Spray Well Whilst Maintaining Functionality?

Structured fluid biomaterials, including gels, creams, emulsions and particle suspensions, are used extensively across many industries, including great interest within the medical field as controlled release vehicles to improve the therapeutic benefit of delivered drugs and cells. Colloidal forces within these materials create multiscale cohesive interactions, giving rise to intricate microstructures and physical properties, exemplified by increasingly complex mathematical descriptions. Yield stresses and viscoelasticity, typically arising through the material microstructure, vastly improve site-specific retention, and protect valuable therapeutics during application. One powerful application route is spraying, a convenient delivery method capable of applying a thin layer of material over geometrically uneven surfaces and hard-to-reach anatomical locations. The process of spraying is inherently disruptive, breaking a bulk fluid in successive steps into smaller elements, applying multiple forces over several length scales. Historically, spray research has focused on simple, inviscid solutions and dispersions, far from the complex microstructures and highly viscoelastic properties of concentrated colloidal biomaterials. The cohesive forces in colloidal biomaterials appear to conflict with the disruptive forces that occur during spraying. This review explores the physical bass and mathematical models of both the multifarious material properties engineered into structured fluid biomaterials and the disruptive forces imparted during the spray process, in order to elucidate the challenges and identify opportunities for rational design of sprayable, structured fluid biomaterials.

Anisotropic Oldroyd-type models for non-colloidal suspensions of viscoelastic particles in Newtonian and yield-stress fluids via homogenization

<h2>Abstract</h2> This talk presents new rheological models, derived by means of homogenization techniques, for non-colloidal suspensions of particles undergoing finite deformations and rotations under Stokes flow conditions. The particles can be nonlinear viscoelastic, or elasto-viscoplastic, while the suspending fluid can be Newtonian or viscoplastic. The microstructure is described by two microstructural ellipsoids, which are allowed to evolve with the flow, characterizing the shape and orientation of the inclusions and the angular dependence of their distribution in space. The models account for particle interactions through the two-point correlation function for the particle centers, in a way that reproduces exactly classical and more recent estimates for dilute suspensions. While special cases of the models have been considered in earlier publications, novel features of this work include the possibility of multiple inclusion families, physically motivated evolutions laws for the particle distributions and more general rheological behaviors for the matrix and inclusions. The resulting models can be viewed as anisotropic generalizations of Oldroyd's invariant models accounting for statistical measures of the microstructure and their evolution.

Slurries of complex fluids: Rheology, microstructure and fluid mechanics

<h2>Abstract</h2> Slurries of complex fluids are suspensions of non-Brownian particles in complex fluids (e.g. shear thinning, shear thickening, yield stress and viscoelastic fluids). These materials exist all around us. Examples include the following: food products, hygiene products, mine tailings, concrete, fracturing fluids, shock absorbing materials, drilling muds and muds in mudslides, lava, and numerous others. As expected from their ubiquity, non-Newtonian slurries contribute significantly to the economy both positively and negatively. Therefore, even small increases in efficiency when processing slurries of complex fluids could make significant positive economic and environmental impacts. Obviously, a thorough understanding of the rheology and fluid mechanics of these materials in natural and industrial settings is essential to improving the efficiency of production. However, this is extremely challenging due to the complex rheology of the suspending fluids, the interaction of fluid and particle phases, and multiple-body and short-range interactions of particles. My presentation will introduce an array of experimental and modelling techniques that my research team uses to investigate rheological properties and fluid dynamical behaviour of the slurries of complex fluids. The goal is to establish a continuum framework and refine it through a series of microstructure investigations. I will discuss how our recent results can be used to address and resolve mixing and pumping problems in concrete industries and to maximizing petroleum reservoir production using hydraulic fracturing processes. Finally, open questions will be disclosed, which must be answered to build a firm foundation for a long-term contribution to the area of complex suspensions.

Unsteady hydromagnetic Couette flow of fluid-particle suspension in a porous channel

Semi-analytic solution representing the time-dependent Couette flow of conducting fluid-particle in a permeable channel is presented in the existence of a magnetic field. The magnetic field is anticipated to be positioned either with the conducting fluid-particle or positioned with the moving wall. Solution to the coupled flow equations is found and given in the Laplace domain. Expressions for fluid-particle velocity and their corresponding skin friction are also found. Influence of a number of flow parameters on flow formation in the permeable channel is demonstrated. Results indicate that, increase in Hartmann number dampens both fluid velocity and particle fluid velocity when the magnetic field is positioned relative to the conducting fluid, while it augments the flow when the magnetic field is positioned relative to the moving plate. In conclusion, it is realized that growing the injection velocity augments the momentum boundary layer yielding an increase in fluid-particle velocity.

Computational analysis on unsteady hydromagnetic Couette flow of fluid—Particle suspension in an accelerated porous channel

In this analysis, Semi-analytical solution representing the time dependent Couette flow of conducting fluid–particle suspension in a permeable channel is offered in the existence of a magnetic field. The magnetic field is anticipated to be positioned either with the conducting suspension or the velocity of the magnetic field is same with the moving wall. Solution to the dimensionless coupled equations are provided by adopting the well known Laplace transform technique and D’Alermbert Method for both flow cases. The obtained solutions are later inverted to the time domain with the help of the Riemann sum approximation. Numerical values for fluid–particle suspension was validated with existing benchmark. Expressions for fluid–particle velocity and their corresponding skin fiction are also found in both cases. Influence of a number of flow parameters on flow formation are demonstrated via graphs. Results indicate that, irrespective of the magnetic field positioned either with the conducting suspension or with the moving wall, injection velocity strengthens the momentum boundary layer yielding an increase in fluid phase velocity and particle phase velocity, whereas the contrast is true with suction.

A homogenization model for the rheology and local field statistics of suspensions of particles in yield stress fluids

We investigate the rheological behavior of athermal particle suspensions using experiments and theory. A generalized version of the homogenization estimates of Ponte Castañeda and Willis [J. Mech. Phys. Solids, 43(12), 1919–1951 (1995)] is presented for the effective viscosity of athermal suspensions accounting for additional microstructural features (e.g., polydispersity) via an empirical parameter, λ. For the case of identically sized spheres dispersed with statistical isotropy in a Newtonian fluid, the parameter λ is estimated from the results of Batchelor and Green [J. Fluid Mech. 56(2), 375–400 (1972)] for the Huggins coefficient. Predictions for the macroscopic viscosity are found to be in good agreement with measurements for monodisperse polymethyl methacrylate (PMMA) spheres in glycerol, as well as for the empirical Krieger–Dougherty equation for the shear viscosity. The proposed estimates have the added benefit that they can also be used to get information on the statistics of the stress and strain-rate fields in the fluid and particle phases. In addition, results for the effective shear viscosity are used in combination with the linear comparison method of Ponte Castañeda [J. Mech. Phys. Solids 39(1), 45–71 (1991)] to generate the corresponding estimates for the effective macroscopic behavior and field statistics of particle suspensions in (viscoplastic) yield stress fluids. Good agreement is also found between the theoretical estimates and experimental results for the effective yield and flow stress of suspensions with monodisperse PMMA spheres in Carbopol. Finally, it is argued that the results for the phase averages and fluctuations of the stress and strain-rate fields can be used to provide a physical interpretation for the parameter λ in terms of the polydispersity of the suspension and its implications for the percolation threshold.

Data-driven closure model for the drag coefficient of the creeping flow past a translating sphere in a shear-thinning viscoelastic fluid

A drag force closure model for particle-laden viscoelastic fluid flows is the key to describing the ensemble-averaged behavior of the mixture. The effects of fluid rheological properties on the flow dynamics of a spherical particle in viscoelastic fluids in the creeping flow regime are parameterized using the Giesekus rheological model. Direct numerical simulations are performed within a large range of Deborah number(0−10).The drag force of a sphere in unbounded Giesekus fluids decreases monotonically with the increase of Deborah number. The negative wake may occur when the viscosity ratio is larger than 0.6 in Giesekus fluids but is absent in Oldroyd-B fluids in all conditions. An explicit closure model for the drag coefficient of a sphere in Giesekus fluids is established using the backpropagation artificial neural network. The drag closure model provides a method for explicitly formulating the momentum exchange model for dilute suspensions of solid particles in shear-thinning viscoelastic fluids.