non-Newtonian Fluid Characteristics Research Articles

Numerical investigation on the enhanced heat transfer characteristics of non-Newtonian viscoelastic fluids in microchannel with chip arrays

Elastic turbulence is an efficient heat transfer method at microscale. In this work, we conduct a systematic investigation on the flow and heat transfer performances of viscoelastic polymer solutions in microchannels with chip arrays by means of high-fidelity numerical simulations. Focusing on the effects of fluid elasticity [i.e. polymer relaxation time (λ)] and flow Reynolds number (Re), we find that the synergistic interplay between inertial and elastic forces is strategically exploited to amplify convection, thereby facilitating an enhanced heat transfer performance. For highly elastic fluid, the Nusselt number (Nu) can be improved by 76.13 % compared to that of less elastic fluid, while the pressure drop is reduced appropriately. In addition, as the fluid elasticity increases, the pressure drop decreases and eventually converges to a constant. In the zone of elastic turbulence, the fluid reinforces the convective heat transfer, which can be ascribe to the deformation of long-chain polymer molecules. Particularly, we consider the effect of temperature-dependent λ on the heat transfer performance. Our results demonstrate that the increased temperature-dependent λ decreases the value of Nu, and the variation between values of variable and constant λ is reduced with increasing Re or λ. Hence, in some cases of large fluid elasticity or high Re, it is possible to safely ignore the impact of temperature-dependent λ with an acceptable accuracy. The present work provides important insights into the enhanced heat transfer via elastic turbulence, which could guide the applications in the field of chip cooling.

Heat transfer analysis of Carreau nanofluid flow with gyrotactic microorganisms: A comparative study

Advancement in thermodynamical characteristics of non-Newtonian fluid is achieved by induction of gyrotactic microorganisms in order to attain efficient thermal and mechanical engineering setups, such as micromixers, microfluidic instruments, biosensors and microdevices. So, the primer motive to conduct this research is to examine the effectiveness of gyrotactic microorganisms in managing heat transport in Carreau nanofluid flow over a linearly stretched surface under the effectiveness of opposing and assisting buoyancy forces. Physical aspect of magnetic field along with slip boundary constraint also entertained by employing in vertical direction. The governing equations are modelled in the form of dimensional PDE's and latterly transformed into dimensionless ODEs via similarity transformations. Solution of obtained set of differential system is solved by implementing Runge-Kutta of order 4 and shooting procedure. Visualizations about influence of flow concerning parameters on associated distributions are analyzed in comparative manner for opposing and assisting buoyancy parameter. In addition, metrics for quantities of engineering interest, such as heat and mass fluxes for nano and gyrotactic particles along with skin friction coefficient are calculated in a comprehensive manner.

Coupling Study on Quasi-Static and Mixed Thermal Elastohydrodynamic Lubrication Behavior of Precision High-Speed Machine Spindle Bearing with Spinning

In this work, a modified numerical algorithm that couples the quasi-static theory with the mixed thermal elastohydrodynamic lubrication (mixed-TEHL) model is proposed to examine the mechanical properties and lubrication performance of the spindle bearing that is used in a high-speed machine tool with spinning. The non-Newtonian fluid characteristics of the lubricant and the non-Gaussian surface roughness are also considered. Moreover, the mechanical properties and lubrication state of the bearing are examined in various service environments. The results indicate that the temperature reduces the lubrication efficiency, which in turn exerts a significant impact on the mechanical properties. The lubrication that either behaves in the manner of Newtonian or non-Newtonian fluid has a relatively negligible influence on the bearing working state, while the non-Gaussian surface roughness significantly alters the oil film thickness and temperature. Calculations with different operating conditions demonstrate that the operating parameters (i.e., axial load, rotation speed) will directly affect the performance of the bearings via the changes in the oil film thickness and the temperature.

A mass transfer-based LES modelling methodology for analyzing the movement of submarine sediment flows with extensive shear behavior

This study employs the large-eddy simulation (LES) method to investigate the interaction of submarine sediment flows with extensive shear behavior and ambient water. This method is validated with good accuracy by simulating the head velocity and evolution geometries of a submarine mud flow with non-Newtonian fluid characteristics and a submarine turbidity current with Newtonian fluid characteristics in inclined and regular lock-exchange flume experiments. This study finds that the violent mass transfer at the interface of the submarine sediment flow and seawater is caused by numerous eddies, which significantly alter the submarine sediment flow's geometry, resulting in varying degrees of undulation, including the deposition pattern of the submarine sediment flow tail. The acceleration zone, where the velocity of the submarine sediment flow increases significantly at this undulation, propels the sediment flow forward, supporting its long-distance transport. Furthermore, the turbulence and mass transport characteristics of submarine turbidity currents with low dynamic viscosity Newtonian fluid characteristics are stronger than those of submarine mud flows with high dynamic viscosity non-Newtonian fluid characteristics. Therefore, when submarine landslides develop into later stages, such as submarine turbidity currents with high velocity, large volume, and long run-out distance characteristics, more attention must be given to the mass transport process.

Rheological study of methane gas hydrates in the presence of micron-sized sand particles

Natural gas hydrates, intricate crystalline structures formed by water molecules and small gas molecules, have emerged as a significant and globally impactful clean energy resource. However, their commercial exploitation faces challenges, particularly operational disruptions caused by sand-related blockages. Understanding the rheological properties of hydrate slurry, especially in the presence of micron-sized sand particles, is imperative for ensuring the flow assurance of subsea hydrate exploitation. This study extensively investigates the rheological properties of sand-containing hydrate slurries. The findings reveal that these slurries exhibit non-Newtonian fluid characteristics, including yield stress, thixotropy, and shear-thinning behavior. Solid-like elastic features are observed in sand-containing hydrate slurries before yielding, transitioning to viscous behavior after yielding. Even with a minimal amount of sand, both static yield stress and yield strain experience substantial changes, correlating with the increase in sand concentration. The research conclusively establishes the thixotropic nature of sand–hydrate slurries, where the viscosity decay rate is directly influenced by the shear rate. These insights aim to contribute comprehensively to the development of effective flow assurance strategies, ensuring the safe and stable operation of subsea hydrate exploitation.

Smoothed Particle Hydrodynamics simulations of integral multi-mode and fractional viscoelastic models

To capture specific characteristics of non-Newtonian fluids, during the past years fractional constitutive models have become increasingly popular. These models are able to capture, in a simple and compact way, the complex behaviour of viscoelastic materials, such as the change in power-law relaxation pattern during the relaxation process of some materials. Using the Lagrangian Smoothed-Particle Hydrodynamics (SPH) method we can easily track particle history; this allows us to solve integral constitutive models in a novel way, without relying on complex tasks.Hence, we develop here a SPH integral viscoelastic method which is first validated for simple Maxwell or Oldroyd-B models under Small Amplitude Oscillatory Shear (SAOS) and start-up channel flows. By exploiting the structure of the integral method, a multi-mode Maxwell model is then implemented. Finally, the method is extended to include fractional constitutive models, validating the approach by comparing results with theory.

Neural network architecture to optimize the nanoscale thermal transport of ternary magnetized Carreau nanofluid over 3D wedge

SignificanceIncorporation of nanoparticles in base fluid water is significant for analysis of thermal behavior of nanofluid mixtures, which has various applications in materials science and thermal engineering, and supervised neural scheme predicts the thermal behavior by solving Carreau nanofluid model. MotiveThis article brings the investigation related to prediction of thermal transport of a ternary magnetized hybrid nanofluid [(Al2O3, CuO, TiO2)/H2O] with a three-dimensional Carreau nanofluid model over a wedge. Three nanoparticles dispersed in water (H2O). Inclined magnetic field is considered for judgement of velocity profile and thermal radiation is utilized to scrutinize the temperature distribution of nanofluid. The Carreau mathematical model is chosen to depict the rheological characteristics of non-Newtonian fluids at very high and very low shear rate. MethodologyPhysical assumptions creates the system of Partial differential equations (PDEs) and these are converted into ordinary differential equations (ODEs) by similarity tool. Further ODEs are dealt with bvp4c scheme and further prediction of solution is made by Levenberg-Marquardt neural network (LM-NN) supervised neural scheme. FindingsIncreased volume friction coefficients of nanoparticles increases the transport of heat. High inclined magnetic effect, thermal radiation, pressure gradient and shear strain parameter predict higher thermal transport.

Numerical Simulation of Hydrodynamics and Mixing Characteristics of High-Viscosity Non-Newtonian Fluid in Twin-Shaft Kneaders

Numerical Simulation of Hydrodynamics and Mixing Characteristics of High-Viscosity Non-Newtonian Fluid in Twin-Shaft Kneaders

Consistent temporal behaviors over a non-Newtonian/Newtonian two-phase flow

The temporal behaviors of non-Newtonian/Newtonian two-phase flows are closely tied to flow pattern formation mechanisms, influenced significantly by the non-Newtonian index, and exhibiting nonlinear rheological characteristics. The nonlinear behavior of fluid flow cannot be directly inferred from the rheological models, making their temporal characteristics difficult to predict. This limitation hinders the development of a unified analytical approach and consistent results, confining researches to case-by-case studies. In this study, sets of digital microfluidics experiments, along with continuous-discrete phase-interchanging schemes, yielded 72 datasets under various non-Newtonian fluid solution configurations, micro-channel structures, and multiple Carreau-related models. Among these datasets, we identified consistent temporal behaviors featuring non-Newtonian flow patterns in digital microfluidics. Generally, selecting the most appropriate model to accurately represent the flow characteristics of non-Newtonian fluids is case-dependent. Nonetheless, there exists a generally applicable description of the flow behavior that is not affected by specific rheological model. This discovery is of significant importance for understanding the common behavioral characteristics of non-Newtonian fluids.

Analysis of active and passive control of fluid with fractional derivative

Numerous researchers have been drawn to the rheology of non-Newtonian fluids because of their diverse uses in the engineering and manufacturing fields, such as lubrication, plastic processing, and mining. Additionally, the characteristics of magnetohydrodynamics non-Newtonian fluids permit its widespread application in computer hard drives, loudspeakers, magnetic resonance imaging, the administration of magnetic medicines, and magnetic hyperthermia. The current work is focused on the analysis of heat and mass transfer in a magnetohydrodynamics Brinkman nanofluid flows across a vertical plate because of these possible uses. The modeling also takes into account the passive and active control of the Brinkman nanofluid. Using suitable nondimensional variables, ordinary differential equations are created from the modeling equations, and the Laplace transform method is used to solve these equations. Semi-analytical solutions for temperature, concentration, and velocity are found after employing the Laplace transform approach to address the issue.

Influence of Suction and Injection on Peristaltic Mechanism of a Jeffrey Nanofluid in a Vertical Channel with Complete Slip Effects

The main goal of the current study is to understand how the peristaltic system of a Jeffrey nanofluid operating in a vertical tube with complete slip properties is influenced by suction and injection. The peristaltic flow was examined by several researchers using various biological fluid types. The majority of the authors used viscous (Newtonian) fluids to illustrate the peristaltic flow mechanism. Because of its uses in industry, non-Newtonian fluids have attracted a great deal of attention. There are numerous models for non-Newtonian liquids because of the complexity of fluids. The Jeffrey fluid model is the most straightforward linear model to depict the non-Newtonian fluid characteristics for which it is reasonable to expect that accurate or analytical solutions would eventually be discovered. Nanofluids are innovative substances that have endless applications in engineering, biology, medicine and other fields. This mathematical model can be used effectively to transport cervical cancer in the tiny blood channels of the cervix. The resulting flow model is then effectively simulated with the appropriate assumptions of a small Reynolds number and long wavelength. The governing conservation equations are then established. Analytical solutions have been found for, pressure rates per wavelength, temperature, velocity and concentrations of nanoparticles in the resultant flow problem. Using the software WOLFRAM MATHEMATICA, the effects of all physical parameters on streamline, velocity, temperature, concentration fields, pressure gradient, frictional force and pressure rate are graphically analyzed. We observed in both 2D-plot and 3D-plot that we increasing the slip parameters β1 and β2 lead to increase the velocity profile. By raising the Jeffrey nanofluid parameter, the pressure rise is decreased. With frictional force, the opposite behavior is observed. The effect of suction and injection parameter k on the trapping bolus, which gets greater as k is higher.

Study on the influence of non-newtonian fluid characteristics on the hydraulic performance and internal flow field of multiphase pump

As a pivotal prospective clean energy source, the secure and efficient extraction of natural gas hydrate has emerged as a forefront concern within the global oil drilling industry in recent years. In this study, a self-developed multiphase pump adapted to "gas-liquid-solid" three-phase mixing is used to extract natural gas hydrate slurries which have non-Newtonian characteristics. Prior research on pumps has primarily focused on water, introducing a significant disparity in handling slurries containing hydrates. This paper investigates the hydraulic performance and flow field variations of a multiphase pump using three different concentrations of Herschel-Bulkley non-Newtonian fluids that exhibit rheological properties similar to natural gas hydrate slurries. Additionally, a viscous Newtonian fluid with seawater as the liquid phase medium is studied for comparison. The results show that the shear-thinning properties of the non-Newtonian fluid improve the efficiency of the pump. However, excessive concentration negatively affects the hydraulic properties. The flow field characteristics such as apparent viscosity and turbulent kinetic energy are closely related to the pump structure and fluid properties. Compared with viscous Newtonian fluid, the non-Newtonian fluid's also have a greater effect on the distribution of gas-solid phases.

Spherical seepage model of Bingham fluid in rough and low-permeability porous media

Based on the microstructure of porous media that exhibits statistical self-similarity fractal features, this paper investigates the radial flow characteristics of non-Newtonian fluids within rough porous media. The analytical equation of permeability and starting pressure gradient of Bingham fluid in low permeability rough porous media are established. It is found that the relative roughness is inversely proportional to the permeability and proportional to the starting pressure gradient. In addition, it is also found that the permeability of low permeability porous media decreases spherically with the increase of radial distance and curvature fractal dimension, and increases with the increase of pore area fractal dimension and porosity. Furthermore, the staring pressure gradient is directly proportional to the radial distance, yield stress and curvature fractal dimension. By comparing the model in this paper with the existing experimental data, the correctness and rationality of the spherical seepage fractal model are effectively verified.

Distribution characteristics of non-Newtonian fluid swirling flow field in a vane-type separator

Most of the fluids encountered in the oil and gas exploitation process exhibit non-Newtonian fluid characteristics, which presents new challenges for the treatment of produced liquid. In this paper, the Eulerian multiphase model and the power law model were coupled to simulate the distribution characteristics of non-Newtonian fluid swirling flow fields in a vane-type separator. Larger oil droplets are able to migrate to the pipe center at relatively weak vortex intensities, which helps to accelerate the formation of the oil core. Due to the rapid decay of the vortex strength, the tangential velocity of the oil droplets drops more rapidly than that of the axial component, thereby reducing the axial energy loss. As the volume fractions of inlet oil increase, the oil core becomes more pronounced, but the convergence of the oil phase gets worse. During the migration, the interaction between dense oil droplets increases the viscosity of the non-Newtonian fluid and decreases the tangential velocity, leading to a maximum apparent viscosity at the center of the pipe. A higher vortex intensity tends to stabilize the vortex core, whilst higher flow velocities, which increases rotational velocities at the exit of the deflection section, deforms the vortex more severely. Moreover, higher inlet flow velocities contribute to better convergence of the oil cores. All these factors are important to better understand the smooth characteristics of non-Newtonian fluids and to provide a theoretical basis for future design and optimization of efficient separators.

Thermal lubrication characteristics of hypoid Gear with non-Newtonian fluids considering roughness

Based on Hertz contact theory and EHL, the model of elliptic contact elastohydrodynamic lubrication considering load, speed, roughness, thermal effect, and shear-thinning effect of non-Newtonian fluids is established. The variation trend of oil film pressure, thickness, and temperature with load, entrainment velocity, and the slide-roll ratio is analyzed. Then, several lubrication states considering roughness, the thermal effect, and the characteristics of non-Newtonian fluid are compared. Compared with the smooth surface, the roughness when RMS is 0.15 μm increases the maximum film pressure (P max) by 8.34%, increases the maximum film temperature (T max) by 7.18%, and reduces the minimum film thickness (H min)by 9.13%. The pressure and temperature are more sensitive to light load. The results are approximate to that of the smooth surface when the entrainment velocity is big enough. The pressure and thickness decrease with the increasing slide-roll ratio. The decreasing speed of the oil film thickness becomes faster as a result of the thermal effect. The roughness and the characteristics of non-Newtonian fluid have a significant impact on temperature.

Evaluating the thermo-physical characteristics of non-Newtonian Casson fluid with enthalpy change

The goal of current study is to scrutinize the boundary layer flow of non-Newtonian Casson fluid flows on the slender parabola of revolution. Due to occurrence of temperature fluctuation in the flow analysis, the thermo-physical properties are presumed as variable. There is need to critically understand its behaviors in crude oil extraction, biomedical industries, textiles, papers, chemicals, machinery and many more processes. The assumed heat and mass transference is calculated by enthalpy change. The modeled equations of unsteady Casson fluid with variable fluid properties occur in the form of PDEs and Levy-Lees similarity transformations are used to convert them in ODEs form. The numerical solutions are calculated with a well-known method namely shooting technique. The variation in velocity field is noted due to the Casson fluid parameter, variable viscosity, suction coefficient and curvature parameter. The impression on temperature is noted by the variation in Damkholer number, thermal conductivity, curvature parameter, heat generation coefficient and Prandtl number. The concentration of fluid is noted due to the curvature parameter, Schmidt number, mass diffusion, Damkholer number and activation energy. At the end, the concluding remarks of the main findings are listed in conclusion section.

Effects of Microfluidization on the Physical and Storage Stability of Walnut Protein Emulsion and Beverages.

Walnut meal is a by-product produced during the production of walnut oil and is often treated as a waste. However, the nutrients in walnut meal mean it has significant potential for development as a plant-based milk. This study investigated the effect of microfluidization on the stability of walnut protein emulsion (WPE) and walnut protein beverage (WPB) produced from walnut meal, compared with conventional homogenization. The particle size, zeta potential, rheological properties, and stability of WPE all significantly improved after microfluidization. The mean particle size and zeta potential of the microfluidized WPE significantly decreased (p < 0.05). The rheological properties demonstrated that the viscosity of the microfluidized WPE decreased by 80%, and that the shear force increased 4.5 times as the shear rate increased. This gave the resulting product the characteristics of non-Newtonian fluid. LUMisizer stability demonstrated that microfluidization improves stability through protein absorption on the oil-water interface. Microfluidization increased the denaturation temperature (Tm) of WPE from 135.65 to 154.87℃. Moreover, microfluidization improved the color, centrifugal precipitation rate, and viscosity in WPB compared to the control at all studied temperatures. The Arrhenius approach was used to establish a shelf-life model, which predicted that microfluidized WPB could be stored for 175 d at 4℃. This study provided a new reference for the widespread application of microfluidization in the production of food-based emulsion and beverage products.

FEM Simulations to Analyze Flow and Thermal Characteristics of Carreau Non-Newtonian Fluid in a Square Cavity

Heat transfer aspects induced by natural convection in enclosures have promising utilizations and essence from theoretical as well as practical prospective like in, nuclear and chemical reactors, electronic devices, cooling, polymeric processes, solar power collection and so forth. After viewing aforementioned extensive practical importance present communicatn is addressed to explain the flow attributes of Non-Newtonian Carreau fluid model in a square cavity. For non-elastic Carreau fluid model expressing the stress and strain relations at infinite and zero stress magnitude. Mathematical formulation of problem is conceded by obliging conservation laws of momentum and energy. A square enclosure with unit dimension is assumed by providing no-slip constraints at all extremities whereas bottom wall is uniformly heated. In order to maintain state of thermal equilibrium in which upper wall is adiabatic and lower and left wall is kept heated and right wall is considered as cold.by incorporation above restrictions on formulated problem equation are attained in partial differential dimensional form. Later on, these expressions are transmuted into dimensionless form by executing variables. Numerical simulation, based on infinite element method by utilizing COMSOL multi physics commercial software is computed. For this purpose, firstly preprocessing involving the steps of meshing at different refinement level is carried out. After this influence of involved dimensionless parameters as flow concerning profile is manifested through graphs and tables. Validation of result is also provided by constructing comparison with existing literature. Grid independence test for heat transfer coefficient is also performed. Engineering interest quantities like kinetic energy, local and average Nusselt number is also computed.

Dynamic analysis of power-law non-Newtonian fluids under low-frequency vertical harmonic vibration by dynamic mode decomposition

Resonance acoustic mixing (RAM) technology applies an external low-frequency vertical harmonic vibration to convey and mix the non-Newtonian fluid across space. However, although this method is used for various applications, its mechanism is yet not well understood. This paper investigates the flow characteristics of the power-law non-Newtonian fluids in RAM by the phase-field numerical simulation method and proposes a mixing index to study the effect of vibration acceleration amplitude, vibration frequency, and filling rate on mixing. Dynamic mode decomposition is used to decompose the vorticity field data into spatial–temporal coherent structures to explore the dynamic mechanism of mixing under the above parameters. The results show that the increase in vibration acceleration amplitude can promote mixing uniformity and rate. The decrease in vibration frequency will increase the mixing of non-Newtonian fluids, but the effect of improvement is no longer obvious when the frequency exceeds a threshold. On the one hand, increasing the vibration acceleration amplitude and decreasing the vibration frequency and filling rate appropriately can induce the 0 Hz and half of the vibration frequency component accounting for the most energy. On the other hand, it can also increase the number of modes traversed by large-scale vortices developing into small-scale vortices. Both of them can improve the mixing rate and uniformity of non-Newtonian fluids.

CFD simulation of hydrodynamics and mixing performance in dual shaft eccentric mixers

This work aims to systematically study hydrodynamics and mixing characteristics of non-Newtonian fluid (carboxyl methyl cellulose, CMC) in dual shaft eccentric mixer. Fluid rheology was described by the power law rheological model. Computational fluid dynamics was employed to simulate the velocity field and shear rate inside the stirred tank. The influence mechanism of the rotational modes, height difference between impellers, impeller eccentricities, and impeller types on the flow field have been well investigated. We studied the performance of different dual-shaft eccentric mixers at the constant power input with its fluid velocity profiles, average shear strain rate, mixing time and mixing energy. The counter-rotation mode shows better mixing performance than co-rotation mode, and greater eccentricity can shorten mixing time on the basis of same stirred condition. To intensify the hydrodynamic interaction between impellers and enhance the overall mixing performance of the dual shaft eccentric mixers, it is critical to have a reasonable combination of impellers and an appropriate spatial position of impellers.