Effects Of non-Newtonian Fluids Research Articles

Nonlinear Electrophoresis of Microparticles in Shear Thinning Fluids.

The nonlinear electric field dependence of particle electrophoresis has been demonstrated to occur in Newtonian fluids for highly charged particles under large electric fields. It has also been predicted to arise from the rheological effects of non-Newtonian fluids even at small electric fields. We present in this work an experimental verification of nonlinear electrophoresis in shear thinning xanthan gum solutions through a straight rectangular microchannel. The addition of polymer into a Newtonian buffer solution is found to change the electric field dependence from linear to superlinear for electroosmotic, electrokinetic, and electrophoretic velocities. The nonlinear index of each of these electrokinetic phenomena increases with the increasing polymer or buffer concentration, among which electrophoresis exhibits the strongest nonlinearity. Both these observed trends are captured by a dimensionless electrokinetic shear thinning number that depends on the power-law index of fluid viscosity and the Debye length.

Non-similar analysis of radially magnetized flow and heat transfer of Reiner–Philippoff based nanofluid over a curved stretching surface with viscous dissipation

The aim of this study is to conduct a non-similar analysis of flow and heat transfer rheology of non-Newtonian fluid over a radially magnetized curved stretching surface in the presence of multiple type of nanoparticles. Reiner–Philippoff viscosity and homogenous models are incorporated in the governing equation to study the effects of non-Newtonian fluid and nanoparticles respectively. Reiner–Philippoff viscosity model is a complicated non-Newtonian fluid model presenting an implicit stress-strain relationship. This fluid model has ability to present viscosity behavior in response to varying viscoelastic conditions of shear-thinning, shear-thickening as well as Newtonian fluid. The nanoparticles of nickel, molybdenum disulfide, and tantalum are used to study the enhancement of the thermal conductivity of the fluid with influences of radiative heat flux and viscous dissipation. To attain a more precise and generalized analysis of the heat transfer and flow, the governing boundary layer equations are converted to non-similar form. The local non-similarity method up to second level of truncation is employed to numerically solve the resulting non-similar PDEs via bvp4c in MATLAB tools. To examine the impact of physical factors on flow and heat transfer, numerical data are visually and tabulated displayed. It is worth mentioning that the thermal radiation, curvature parameter, and magnetic number play important role in controlling wall drag and heat flux.

An Magnetohydrodynamics Effect of Non-Newtonian Fluid Flows Over a Stretching/Shrinking Surface with CNT

An Magnetohydrodynamics Effect of Non-Newtonian Fluid Flows Over a Stretching/Shrinking Surface with CNT

Numerical Analysis of Non-Newtonian Fluid Effects on the Equilibrium Position of a Suspended Particle and Relative Viscosity in Two-Dimensional Flow

A solvent in suspension often has non-Newtonian properties. To date, in order to determine these properties, many constitutive equations have been suggested. In particular, power-law fluid, which describes both dilatant and pseudoplastic fluids, has been used in many previous studies because of its simplicity. Then, the Herschel–Bulkley model is used, which describes fluid with yield stress. In this study, we considered how a non-Newtonian solvent affected the equilibrium position of a particle and relative viscosity using the regularized lattice Boltzmann method for fluid and a two-way coupling scheme for the particle. We focused on these methods so as to evaluate the non-Newtonian effects of a solvent. The equilibrium position in Bingham fluid was closer to the wall than that in Newtonian or power-law fluid. In contrast, the tendency of relative viscosity in Bingham fluid for each position was similar to that in power-law fluid.

Innovation modeling and simulation of thermal convective on cross nanofluid flow over exponentially stretchable surface

This work reported to investigate convective flow of non-Newtonian fluid effect on an exponentially stretchable surface. Effect of nanoparticle is considered in heat and mass equation. The transformation technique utilized on dimensionless equations is converted to non-dimensionless equations are solved thought numerical approach Bvp4c. Influence of approatiate analysis of velocities, heat and mass transport are scrutinized through figures. Furthermore, the comparative analysis of drag forces, Nusselt number and Sherwood number are evaluated over and done with tabulated values. It is give details that the temperature field strengthens with intensification in thermophoresis and random diffusions. Similarly, rises in thermophoresis effect parameter both temperature and concentration profile increasing.

The Effect of Non-Newtonian Fluid Midsole Footwear on Lower Limb Biomechanics after 5 km of Running in High Temperature

This study’s aim was to examine the effect of non-Newtonian fluid (NN) shoe and ethylene vinyl acetate (EVA) shoe on human lower limb biomechanics and muscle activation during running in hot temperatures. Thirty-five men utilizing a rearfoot strike ran 5 km at a self-selected tempo at an average summer temperature of 41.7 ± 1.0 °C and relative humidity of 80.7 ± 3.5%. The kinematics, kinetics, and muscle activation of the right leg were monitored from landing until the pedal was off the ground. A two-way repeated-measures ANOVA was conducted to investigate the main effects of the shoe condition, temperature, and interaction effect. Wearing NN at high temperature resulted in increased hip range of motion (ROM) (p = 0.001). The knee torque increased significantly when wearing EVA and NN shoes after the temperature increased (p = 0.006). When wearing EVA and NN, the ground reaction force (GRF) and loading rate (LR) increased significantly after the temperature increased (p = 0.001; p = 0.009). When wearing NN after running for 5 km at a high temperature, the displacement range of center of pressure (COP) was significantly reduced (p < 0.001), while the EVA was significantly increased (p < 0.001). Neither pair of shoes substantially altered muscle activity. After excluding the factor of fatigue, the increase in temperature not only changed the properties of the material inside the shoe, but also changed the parameters of the biomechanics of the human lower limbs. After the temperature increases, the shoes made of non-Newtonian fluid materials can quickly stabilize under the condition of increased shear stress and reduce the displacement of the human body. Thus, it indicated that non-Newtonian fluid shoes may lower the risk of injury when running in extremely hot conditions.

Non-Newtonian nanofluids mediated 15-fold enhancement of mass transfer for two-phase flow systems in microchannel

Microfluidic systems have been more popular in recent years because of its multifunctional advantages, such as the higher level of process intensification. The mass-transfer properties can further be improved by the presence of the slug flow regime in the microdomain for biphasic flow systems. Microdomain, geometrical considerations, non-Newtonian fluid and nanofluid have been independently being investigated as a tool of process intensification. To the best of our understanding, the four-in-one method of process intensification has not been studied till date hence, new systems are being investigated to bridge the gap. In this work, we describe the combination of three enhancing factors - microdomain, slug flow and non-Newtonian nanofluids (NNnF) on hydrodynamic and mass transfer studies for two-phase flow systems. The effect of non-Newtonian fluid (NNF) on the flow pattern and mass transport properties of an immiscible liquid-liquid system in straight and helical microchannels with internal diameters of 0.15 mm and 0.25 mm is being explored experimentally as well with CFD simulations. The range of slug flow has been increased along with enhancement of mass transfer coefficient with the introduction of non-Newtonian nanofluid. Unprecedentedly the addition of 0.5% (w/v) carboxy methyl cellulose (CMC) and Nickel (Ni) nanoparticles has resulted in fifteen times enhancement of mass transfer coefficient.

Effect of Non-Newtonian Fluid on Mixing Quality and Pressure Drop in Several Static Mixers: A Numerical Study

Effect of Non-Newtonian Fluid on Mixing Quality and Pressure Drop in Several Static Mixers: A Numerical Study

Non-Newtonian Effects of Blood Flow on Hemodynamics in Pulmonary Stenosis: Numerical Simulation

This paper aims to explore the construction of an individualized pulmonary artery stenosis model based on computed tomography (CT) images. The stenosis model is simulated using a porous medium, and the numerical simulation is carried out by computational fluid dynamics (CFD) method to discuss non-Newtonian effects on hemodynamics. The hemodynamic parameters and quantitative pulmonary pressure ratio (QPPR) of the right pulmonary artery stenosis are obtained. The change curves of hemodynamic parameters show that the effects of non-Newtonian fluid are more significant than those of Newtonian fluid. Under the non-Newtonian condition, pressure and velocity drop more and faster when blood flow enters into the stenosis region. There is a high wall shear stress in the stenosis downstream. The margin of error between the QPPR value of the non-Newtonian fluid simulation and the clinical measurement value is not more than 10%. This work provides the evidence that the simulation of non-Newtonian fluid is closer to the reality when a porous medium model is used in a stenosis model. This contributes to assessing the severity of pulmonary stenosis behavior and is essential to guide disease treatment.

Energy loss and mechanical efficiency forecasting model for aero-engine bevel gear power transmission

• Numerical loaded tooth contact analysis for meshing interface. • Meshing interface state evolution under TEHL condition. • Non-Newtonian fluid ETHL model considering entrainment angle. • Separation flow method for the friction coefficient determination. • Energy loss and mechanical efficiency forecasting model. Energy loss and mechanical efficiency directly affect the service performance and reliability of aero-engine bevel gear power transmission, but there is currently a lack of effective diagnosis in early design stage due to the complex tooth meshing interface state evolution under the thermal elastohydrodynamic lubrication (TEHL) condition. A new energy loss and mechanical efficiency prediction model is proposed by using the improved TEHL analysis considering the entrainment angle and non-Newtonian fluid effect. Firstly, numerical loaded tooth contact analysis (NLTCA) is developed to determine tooth meshing kinematic relating to the entrainment and sliding states. Then, the entrainment angle is taken into account the Non-Newtonian fluid TEHL model and separation flow method is applied for friction coefficient solution. Finally, new energy loss and mechanical efficiency model is established by simulating the complex tooth meshing interface TEHL. This model is enabling ever-higher levels of aero-engine bevel gear production efficiency and design sustainability. It can provide an important access to geometric and physical assessments that can improve the energy generation, conversion, transfer and utilization of the whole aero-engine power transmission system. .

Experimental study of unconventional modified filling energy absorption and control mechanism in high energy storage rock masses

Aiming at the problems that it is difficult to predict rock burst accurately in engineering practice and the implementation parameters of rock burst prevention measures depend on some empirical formulas, in order to study the advantages and disadvantages of different in-situ modification mechanisms deeply, determine the applicable conditions of unusual in-situ modification measures, and provide a theoretical basis for forming adaptive in-situ modification control schemes. Two kinds of modified control methods using the same foundation involve engineering scale and indoor scale. With the help of scale transformation, the whole failure process analysis test of bearing rock samples was carried out. The results show that various modification measures can effectively control the properties, and realize "hard-rock softening or soft-rock hardening" by changing the physical and mechanical parameters of the target rock sample. Compared with the control group, the automatic parameters of rocks deteriorated significantly under different modification measures. The evolution law of carrying energy is similar. However, there are obvious diversity between various modification measures in plastic stage and post-peaking phase stage, which provides favorable conditions for rock burst prevention. Based on this, an adaptive modification control system was constructed. At the same time, filling materials is considered to increase the energy of post-peaking phase (non newtonian fluid: energy-absorbing materials), and further slow down the intensity of released energy within post-peaking phase stage. Because rock burst is characterized by rapid release of energy, non newtonian fluid has a good absorption effect on high-speed impact force. Therefore, in the design test, the effect of non newtonian fluid is realized by applying a high loading rate, and the evaluation of energy absorption effect of bearing rock samples filled with non newtonian fluid in borehole is considered.

Numerical analysis of thermophoresis of charged colloidal particles in non-Newtonian concentrated electrolyte solutions.

Thermophoresis of colloidal particles in aqueous media is more frequently applied in biomedical analysis with processed fluids as biofluids. In this work, a numerical analysis of the thermophoresis of charged colloidal particles in non-Newtonian concentrated electrolyte solutions is presented. In a particle-fixed reference frame, the flow field of non-Newtonian fluids has been governed by the Cauchy momentum equation and the continuity equation, with the dynamic viscosity following the power-law fluid model. The numerical simulations reveal that the shear-thinning effect of pseudoplastic fluids is advantageous to the thermophoresis, and the shear-thickening effect of dilatant fluids slows down the thermophoresis. Both the shear-thinning and shear-thickening effects of non-Newtonian fluids on a thermodiffusion coefficient are pronounced for the case when the thickness of electric double layer (EDL) surrounding a particle is moderate or thin. Finally, the reciprocal of the dynamic velocity at the particle surface is calculated to approximately estimate the thermophoretic behavior of a charged particle with moderate or thin EDL thickness.

An experimental performance comparison of Newtonian and non-Newtonian fluids on a centrifugal blood pump

The use of substitute fluid with similar rheological properties instead of blood is important due to ethical concerns and high blood volume consumption in pump performance test before clinical applications. The performance of a centrifugal blood pump with hydrodynamic journal bearing is experimentally tested using Newtonian 40% aqueous glycerin solution (GS) and non-Newtonian aqueous xanthan gum solution of 600 ppm (XGS) as working fluids. Experiments are performed at four different rotational speeds which are 2700, 3000, 3300, and 3600 rpm; experiments using GS reach between 8.5% and 37.2% higher head curve than experiments using the XGS for every rotational speed. It was observed that as the rotational speed and flow rate increase, the head curve difference between GS and XGS decreases. This result can be attributed to the friction reduction effect when using XGS in experiments at high rotation speed and high flow rate. Moreover, due to different fluid viscosities, differences in hydraulic efficiency were observed for both fluids. This study reveals that the use of Newtonian fluids as working fluids is not sufficient to determine the actual performance of a blood pump, and the performance effects of non-Newtonian fluids are remarkably important in pump performance optimizations.

3-D numerical simulation of sandstone matrix acidizing by non-Newtonian fluid

Matrix acidizing is a common technique to increase oil recovery in sandstone oil reservoirs. In the matrix acidizing process, reactive fluids are injected into the reservoir with the scope of dissolving and dispersing the rocks near the wellbore.In this study, the matrix acidizing of sandstone wells by a hydrochloric acid/hydrofluoric acid/additives mixture is described through mathematical modeling using the two-scale continuum model.The model developed in this study indicates the reactions and transport phenomena at pore and Darcy scales in 3-D radial flow. Due to using several additives during the acid injection process, the fluid phase has non-Newtonian behavior (shear-thinning). The effect of non-Newtonian fluid in porous media was investigated using a modified continuum model due to importance calculations in field scale. The Carreau-Yasuda constitutive equation has been used to modify the continuum model to consider the non-Newtonian fluid effects. In the proposed model, partial differential equations of reaction and diffusion at pore-scale, and simultaneously convection and dispersion phenomena at Darcy scale are solved using numerical methods. The finite volume and tri-diagonal matrix algorithm (TDMA) techniques were employed to gain a precise solution for the model and observe the dissolution pattern in different acidizing regimes and rheological properties. The effect of acid injection rate, dissolution rate constant and different reservoir properties, including permeability, porosity and heterogeneity on dissolution patterns, was investigated by considering non-Newtonian fluid effects, and concluded that acid having high shear-thinning behaviour (i. e., acid having low power-law index) seemed more promising for field operations because of deep penetration. The reservoir heterogeneity was defined by selecting a random local porosity distribution.It should be noted that the presented model can reproduce different types of acid/rock system (carbonate or sandstone reservoirs). Finally, the skin factor would be calculated to study the acidizing performance in the damaged zone. To solve the porosity evolution equation, couple pore and Darcy scales, and update the pore-scale parameters at each time step, the program was developed in FORTRAN by Parallel Processing and consisting of functions and routines. • Simultaneous numerical solution of Darcy, mass and pore equations in 3-dimension. • 3-D modeling of sandstone matrix acidizing by non-Newtonian fluid. • Pore volume to breakthrough and injection rate calculations in various conditions. • Consideration of power-law index (n) and viscosity effects in dissolution patterns. • Consideration of skin factor variation during the matrix acidizing.

Optimum design of micromixer for a non-Newtonian fluid by topology optimization

Improving the mixing performance is a crucial and widely concerned topic in microfluidic devices for low Reynolds numbers (Re). In this paper, the mixing unit as the design domain in a typical T-shape micromixer considering non-Newtonian fluid effects is investigated using topology optimization. The objective of topology optimization is to maximize the mixing quality under the prescribed pressure drop of the micromixer. Based on the optimized structures obtained by topology optimization, high-fidelity calculations are performed to eliminate the influence of the greyscale problem. For the Newtonian fluid, the optimized structure has better mixing performance than the reference structure with the same pressure drop. For the non-Newtonian fluid, cross-comparison is conducted to obtain the optimized structure. The results show that the mixing qualities of the 25-period mixing unit are 93.90% (Newtonian fluid, Re = 8) and 93.84% (non-Newtonian fluid, Re = 0.24), respectively.

Thermal and rheological investigation of non-Newtonian fluids in an induced-charge electroosmotic micromixer

Microfluidic devices have drawn many researchers in the various fields of area such as biomedical diagnostics, biological and chemical analysis. Among these applications, micromixing has a prominent impact on the efficiency and sensitivity of microfluidic devices. In this study, an induced-charge electroosmotic solver with the presence of Joule heating effects has been developed in the open-source code package, OpenFOAM, to investigate the rheological effects of non-Newtonian fluids in a trapezoidal micromixer. The mathematical model and the developed solver are validated with existing data in the literature and the effects of micromixer geometry, various applied DC electric potential, rheological effects of fluid and the heat transfer are studied to attain an efficient micromixer. Results show that the proposed micromixer offers the advantages of high mixing efficiency with a high flow rate in comparison to other investigated geometries. Newtonian, Shear-thinning, and shear thickening fluids are studied in this article and it is shown that in Newtonian fluid and shear-thinning fluid, the mixing efficiency is enhanced by amplifying the applied electric field which can be concluded that the effects of vortices have more impact on mixing efficiency in comparison to the flow rate. On the other hand, in shear thickening fluid, the mixing efficiency is decreased by amplifying the electric field, because the flow rate is enhanced which leads to the increment of fluid viscosity and decrement of the strength of vortices. Finally, to analyze the fluid temperature rising because of the presence of Joule heating, the heat transfer is studied to assure the health of cells in the proposed micromixer.

Multi-objective optimization of heat transfer in microchannel for non-Newtonian fluid

This paper presents a multi-objective topology optimization method for convective heat transfer problems based on Navier-Stokes and heat transport equations. In this research, the pressure drop (or energy dissipation) function and the recoverable thermal power function are combined and optimized as a multi-objective function. A Pareto algorithm is constructed, based on a weighted-sum method using different weight coefficients. The Pareto solutions composed of a set of optimal solutions are obtained to reveal the trade-off relationship between the objective functions. The effects of non-Newtonian fluid on the flow-channel arrangement and heat transfer performance are numerically studied. In the numerical method, the interpolation term in the density-based topology optimization method is modified, while the filtering method is used to solve the problems of grayscale and the flow channel discontinuity. The results show that the differences between the optimal structures for non-Newtonian fluid and Newtonian fluid are more obvious at Re = 0.01 in the dual-terminal devices. Under the same situation, blood (non-Newtonian fluid) has greater energy dissipation and better heat transfer performance than water (Newtonian fluid).

Inverse Design and Flow Distribution Analysis of Carreau Type Fluid Flow through Coat-Hanger Die

An analytical/numerical method is revisited and proposed for process material specific design of coat-hanger dies. For this aim, both representative viscosity approach (RVA) and electrical network method (ENM) are employed in combination within an iterative calculation process. Under favour of RVA, any viscosity model from the family of generalized Newtonian fluid models such as that of Carreau-Yasuda can be used within broad extrusion rate range in ENM without limitation in low and high values of shear rates. This provides great flexibility and accuracy in ENM which is a relatively simple and fast numerical method. First, this method is employed to design die geometry for a specific thermoplastic melt that provides uniform flow rate at the die exit. Later, the same method is modified and used to investigate the effects of non-newtonian fluids with varying power-law indices on the die performance. Evaluation of the performance of ENM coupled with RVA (ENM-RVA) is made by computational fluid dynamics (CFD) analyses. CFD analyses indicated that the method is very successful in designing die geometry for a specific fluid. Flow distributions predicted by the method for various fluids are in accordance with those of CFD runs. The ENM-RVA is a design/analysis technique which can be employed to see effects of material rheology and throughput on the coat-hanger die performance in a short time and can be used as an auxiliary tool which can provide the preliminary design geometry for the advanced design softwares working with optimization algorithms.

On the Weissenberg effect of turbulence

Within the framework of the Navier–Stokes equations, the Weissenberg effect of turbulence is investigated. We begin with our investigation on the elastic effect of homogeneous turbulent shear flow. First, in the sense of Truesdell (Physics of Fluids, 1964) on the natural time of materials, we derive the natural time of turbulence, and use it together with the natural viscosity of turbulence derived in the article of Huang et al. (Journal of Turbulence, 2003) to define the natural Weissenberg number of turbulence as a measure of the elastic effect of homogeneous turbulence. Second, we define a primary Weissenberg number of turbulence, which in laminar flow reduces to the Weissenberg number widely applied in rheology to characterize the elasticity of visco-elastic fluids. Our analysis based on the experimental results of Tavoularis and Karnik (Journal of Fluid Mechanics, 1989) indicates that the larger is the Weissenberg number of turbulence, the more elastic becomes the turbulent flow concerned. Furthermore, we put forth a general Weissenberg number of turbulence, which includes the primary Weissenberg number of turbulence as a special case, to measure the overall elastic effects of turbulence. Besides, it is shown that the general Weissenberg number can also be used to characterize the elastic effects of non-Newtonian fluids in laminar flow.

Magnetohydrodynamic flow of continuous dusty particles and non-Newtonian Darcy fluids between parallel plates

The coupled unsteady power-law conducting fluid flow and continuous dusty viscous fluid flow under the influence of magnetic field are solved using the finite difference method. The resistive forces of Darcy porous medium and the external uniform magnetic field are applied on the flow. The second-order accurate finite difference schemes are applied on the coupled governing equations to transform the non-linear partial differential equations to linearized system of algebraic equations. This system is solved iteratively using the generalized Thomas algorithm. Some results are introduced to study the convergence and stability of the present works. The effects of non-Newtonian fluid, continuous dusty particles, Darcy model on the velocity field, and friction factor of both the fluid and dust particles phases are demonstrated.