Effect Of Fluid Viscosity Research Articles

Simulation of Particle-Fluid Interaction in Fractal Fractures Based on the Immersed Boundary-Lattice Boltzmann Method

In order to reveal the influence of particles on fluid flow characteristics in rough fractures under fluid-solid coupling, a range of fracture systems with varying roughness were generated using the Weierstrass-Mandelbrot function. Fluid-particle interactions in rough fractal fractures were simulated using the immersed boundary-lattice Boltzmann method. In this paper, the effects of fluid viscosity, particle size, particle quantity, fracture fractal dimension, and particle grading composition are studied. Results illustrate that increasing fluid viscosity hinders the movement of particles, resulting in the decreasing of particle velocity. As particle size and particle quantity increase, the particle occupation of the channel area grows larger, which lead to lower permeability of the channel. Increasing fracture fractal dimension surges the curvature of the fluid channel, but permeability has a negative exponential correlation to fractal dimension. With increasing particle grading composition, the blocking effect of particles on fracture flow also increases with increasing particle proportion.

Influence of an Integral Heave Plate on the Dynamic Response of Floating Offshore Wind Turbine Under Operational and Storm Conditions

The hydrodynamic performance of the floating foundation for offshore wind turbines is essential to its stability and energy harvesting. A semi-submersible platform with an integral heave plate is proposed in order to reduce the vertical motion responses. In this study, we compare the heave, pitch, and roll free decay motions of the new platform with a WindFloat-type platform based on Reynolds-Averaged Navier-Stokes simulations. The differences of the linear and quadratic damping properties between these platforms are revealed. Then, a FAST (Fatigue, Aerodynamics, Structures, and Turbulence) model with the consideration of fluid viscosity effects is set up to investigate the performance of the new platform under storm and operational conditions. The time-domain responses, motion spectra, and the mooring-tension statistics of these two platforms are evaluated. It is found that the integral heave plate can increase the viscous hydrodynamic damping, significantly decrease the heave and pitch motion responses, and increase the safety of the mooring cables, especially for the storm condition.

Model of nanostructural layers formation at long-term operation of rails

A mathematical model was developed and a mechanism was proposed for the formation of nanoscale structural-phase states on the example of rail steel at long-term operation. It was believed that during intense plastic deformations, the material behaves like a viscous incompressible fluid. In order to take into account the sliding of the wheel relative to the rail, a two-layer fluid model was proposed, the top layer of which slides at a certain speed relative to the first. In this case, the Kelvin-Helmholtz instability develops. For each layer, we have written the Navier-Stokes equations and kinematic and dynamic boundary conditions. Solution of the obtained system in the form of normal perturbation modes was carried out on the basis of assumption of the viscous-potential material flow. In this approximation, it was believed that viscosity effects occur only at the layer interface. A dispersion equation was derived, which was analyzed using a graphical representation of the functions included in the analytical solution. A range of characteristics of the material and parameters of the external influence (the velocity of the layer) was established, at which two peaks are observed in dependence of disturbances growth rate on the wave number. The first (hydrodynamic) maximum is due to the motion of the layers relative to each other; the second is associated with the effects of fluid viscosity. Approximate formulas were obtained for dependence of the growth rate of perturbations on the wave number. Conditions for realization of only one maximum were found. The viscously determined maximum at slip velocities of the order of 1 m/s can be in the nanoscale wavelength range. Assuming that the white layer in the rails during long-term operation is formed mainly due to the action of intense plastic deformations, we believe that the obtained results detail the mechanism of white layers formation in the rails in this case.

Effect of Geometry and Fluid Viscosity on Dynamics of Fluid‐Filled Cracks: Insights From Analog Experimental Observations

AbstractFluid‐filled volumes in geological systems can change the local stress field in the host rock and may induce brittle deformation as well as crack propagation. Although the mechanisms relating fluid pressure perturbations and seismicity have been widely studied, the fluid‐solid interaction inside the crack of a host rock is still not well understood. An analog experimental model of fluid intrusion in cracks between planar layers has been developed to study stress conditions at the margins and tips. A combined high‐speed shadowgraph and a photoelasticity imaging system is used to visualize the fluid dynamics and induced stresses on the solid matrix. Cavitation, as well as bubble growth and collapse, occurs along the sawtooth crack margins, which produces a highly localized stress concentration to initiate new subcrack systems. The presence of the bubbles at the crack tip during fluid pressure perturbation can enhance crack propagation.

Effects of Fluid Viscosity and Two-Phase Flow on Performance of ESP

Electric submersible pumps (ESPs) are widely used in the oil and gas industry for crude-oil lifting, especially in subsea oil fields or underground storage caverns. The failure of ESPs causes a large economic cost mainly attributed to a break in production continuity, as the ESP cannot be easily replaced. Therefore, the assurance of safe and efficient operation of ESPs has attracted high attention in recent years, although the problem still remains challenging given the complexity of carrying fluid and the mechanical structure of the ESP. In this article, we systematically review both the high-impact, classic contributions and the most up-to-date, current opinions in experimental and numerical advances of viscous effects and two-phase flow in ESPs. We specifically focus on the applications in the oil and gas industry and point out a few current challenges in the operation of ESPs. We aim to guide the audience which is new to the area of ESPs to the correct articles related to their interests, including classic work and recent advances.

Numerical investigation of fluid property effects on formation dynamics of millimeter-scale compound droplets in a co-flowing device

Effects of fluid property on the formation of millimeter-scale compound droplets in a co-flowing device were systematically investigated via a simulation method using the VOF-CSF model. The simulation shows that compound droplets are formed in three regimes, namely, dripping regime, transition regime, and jetting regime. Increasing the flow rate or viscosity of outer fluid cause flow regime to convert from dripping to jetting, and the diameter of droplet significantly decreases. However the effects of inner fluid viscosity on formation dynamics always appear various, where the breakup mode of core droplet can be significantly changed, but the influences on its geometric dimensions can be ignored. In addition, the effects of internal and external interface tension are also further discussed. Finally, a dimensionless number ξ is proposed to predict the flow regimes of compound droplets formation. The results could provide theoretical guidance for controllably preparing monodisperse millimeter-scale compound droplets with specific size.

Vibration Power Flow of an Infinite Cylindrical Shell Submerged in Viscous Fluids

In the previous investigations of the vibroacoustic characteristics of a submerged cylindrical shell in a flow field, the fluid viscosity was usually ignored. In this paper, the effect of fluid viscosity on the characteristics of vibration power flow in an infinite circular cylindrical shell immersed in a viscous acoustic medium is studied. Flügge’s thin shell theory for an isotropic, elastic, and thin cylindrical shell is employed to obtain the motion equations of the structure under circumferential-distributed line force. Together with the wave equations for the viscous flow field as well as continuity conditions at the interface, the vibroacoustic equation of motion in the coupled system is derived. Numerical analysis based on the additional-damping numerical integral method and ten-point Gaussian integral method is conducted to solve the vibroacoustic coupling equation with varying levels of viscosity. Then, the variation of the input power flow against the nondimensional axial wave number in the coupled system with different circumferential mode numbers is discussed in detail. It is found that the influence of fluid viscosity on the vibroacoustic coupled system is mainly concentrated in the low-frequency band, which is shown as the increase of the crest number and amplitude of the input power flow curves.

Enhanced heat transfer research in liquid-cooled channel based on piezoelectric vibrating cantilever

In order to study the variation of vortices and heat transfer enhancement characteristics of piezoelectric vibrating cantilever in liquid-cooled channels, the effects of fluid density and viscosity, mainstream velocity, and excitation voltage on vortices were analyzed. The theoretical and numerical simulation of piezoelectric vortices was carried out by using fluid-solid coupling method. On the basis of hydrodynamic function considering the additional effect of liquid viscosity and density on piezoelectric vibrator, the vortex structure of piezoelectric vibrator was analyzed by panel method free-wake model. It is found that the larger the density of the liquid, the smaller the vortex shedding strength and the radius of the core. The larger the viscosity of the liquid, the easier to fully develop the vortex generated by the excitation. The increase of the mainstream flow velocity is beneficial to the development of the vortex structure and the increase of the vorticity intensity. Compared with the increase of the mainstream flow velocity, the excitation voltage is more conducive to the enhancement of the vorticity structure, then make it easier to mix hot and cold fluids, thus enhancing heat transfer.

The Effects of Stiffness, Fluid Viscosity, and Geometry of Microenvironment in Homeostasis, Aging, and Diseases: A Brief Review.

Cells sense biophysical cues in the micro-environment and respond to the cues biochemically and biophysically. Proper responses from cells are critical to maintain the homeostasis in the body. Abnormal biophysical cues will cause pathological development in the cells; pathological or aging cells, on the other hand, can alter their micro-environment to become abnormal. In this minireview, we discuss four important biophysical cues of the micro-environment-stiffness, curvature, extracellular matrix (ECM) architecture and viscosity-in terms of their roles in health, aging, and diseases.

Scalar and vector viscous wave equations of fluid bounded by solid boundaries

Quadrupole sources in the acoustic analogies developed by Lighthill, Curle, and Ffowcs Williams and Hawkings, include the effect of fluid viscosity on both sound generation and propagation. However, all or partial quadrupole sources are usually ignored to save the computational cost, and this simplification also ignores the effect of fluid viscosity on sound propagation. In this paper, viscous scalar and vector wave equations, and the corresponding acoustic pressure, acoustic velocity and vortical velocity integral formulations are derived analytically to separate the effect of fluid viscosity on sound generation and propagation. An acoustic energy balance equation for the viscous fluid is derived analytically. The developed equation reveals two types of acoustic dissipation mechanisms, namely, the viscous dissipation and the acoustic-vortical interaction. The viscous dissipation occurs during the entire sound-propagation process but the acoustic-vortical interaction occurs mainly in the near field around sources because the vortical wave usually decays rapidly away from the sources. Using the developed analytical formulations, the acoustic power loss caused by fluid viscosity is calculated and analyzed.

Fluid Mechanics of Pneumatic Soft Robots.

Pressurization of gas within embedded channels and cavities is a popular method for actuating soft robots. Various previous works examined the effects of internal fluid mechanics on this actuation approach, as well as on leveraging viscous effects to extend the capabilities of soft robots. However, no existing works studied the combined effects of fluid viscosity and compressibility, relevant to miniaturized configurations, which is the aim of the current work. We derive a general model for compressible viscous flow in an elastic media representing a simplified miniaturized soft robot. We illustrate applying this model to periodic configurations, simplifying it via a long-wave approximation. Steady, and time-dependent solutions are obtained, allowing to model the flow and to provide insight into the actuation dynamics of miniaturized pneumatic soft robots.

Comprehensive proppant settling model in hydraulic fractures of unconventional gas reservoir considering multifactorial influence

Thus far, hydraulic fracturing has played a crucial role in improving the production of unconventional gas resources. During hydraulic fracturing, the proppant is pumped into an artificial fracture with a low-viscosity fracturing fluid. Then, the proppant settles and makes the artificial fracture open. Therefore, the investigation of proppant settling in the hydraulic fracture is important for the development of unconventional gas reservoirs. This paper proposes a comprehensive mathematical model for quantitatively evaluating the proppant settling rate in the hydraulic fracture of unconventional gas reservoirs. In particular, the model considers the effects of fracture width, proppant size, proppant concentration, fluid viscosity, and flow regime. The model is verified by the experimental data and models found in literatures, and the effects of key parameters (e.g., fluid viscosity, concentration, fracture wall, proppant size, and flow regime) on the settling rate are analyzed. The results show that, with increasing fracture width or decreasing proppant diameter, the dimensionless settling rate increases. By contrast, fluid viscosity has a small effect on the dimensionless settling rate. In addition, the increase of proppant concentration results in a decrease in the dimensionless settling rate. The proppant concentration is the main factor affecting the settling rate, followed by the flow regime, the ratio of proppant diameter to fracture width, and the fluid viscosity. This work can provide a theoretical basis for the study of proppant placement in fractures of unconventional gas reservoirs. Additionally, the developed model can be easily incorporated into fracture simulators to simulate proppant transport.

The influence of fluid type on elastic wave velocity and attenuation in volcanic rocks

Volcano-seismic signatures are the convolution of source and path effects. The source signature provides important information about the dynamic rock deformation and fluid resonance processes within the volcano, but path effects are the result of the volcanic plumbing, the edifice physical conditions, and the complex geological structure. Complicating the inversion of seismic data further, is the influence of fluid properties. Here, we use ultrasonic experiments to understand the effect of variable fluid viscosity and bulk modulus on P-wave attenuation and velocity for volcanic rocks from White Island volcano (Whakaari), New Zealand.Our experimental conditions for high-porosity ash tuff and low-porosity lava resemble shallow and deep volcano facies respectively. P-wave velocity, Vp, and quality factor, Qp, increase with the viscosity and bulk modulus of the saturating fluid and decrease with porosity and fracture volume. Tuffs are highly sensitive to saturating fluid, with variations in Vp of up to 67% and Qp of 383%. Vp and Qp in fractured lavas are slightly less sensitive to fluids (24% and 296% respectively), but Vp can be used to identify lithology for these tuff vs. lavas. Comparison of the experimental data with rock physics models suggests that squirt flow is the dominant attenuation mechanism for viscosities greater than that of water, while scattering losses may be important in gas saturated rocks. Our results have significant implications for the interpretation of seismic tomography studies and for volcano hazard monitoring based on the characteristics of detected seismicity.

Nanoparticle plugging prediction of shale pores: A numerical and experimental study

The combination of energy modeling and nanotechnology has been receiving increasing attention. Researchers have discovered that nanoparticles can plug shale pores. However, currently, information about the blocking effect of nanoparticles on shale pores is largely limited to physical experimental data. The migration, dynamic accumulation, and blocking mechanism of nanoparticles in a drilling fluid after intrusion into shale pores remain unclear. In this study, a CFD-DEM model was used to dynamically predict the quantitative relationship between nanoparticle parameters, fluid properties, and the shale pore plugging efficiency. To ensure rationality, UDF codes were written to correlate the standard drag curve. The results indicate that increasing the viscosity to 5 mPa·s is a highly effective method for improving the plugging efficiency at 1 wt% particle concentration. In addition, the effects of particle size, concentration, and fluid viscosity on the plugging effect are observed to be positively correlated. The plugging efficiency of a solution with 5 mPa·s viscosity was improved by 8.6%, 18.81%, and 18.77% compared with that of a solution with 1 mPa·s viscosity at particle sizes of 1/5, 1/3, and 1/2, respectively. Moreover, a pore roughness of 3% and a fluid viscosity of 5 mPa·s were determined to be the thresholds for improving the particle plugging efficiency. In addition, the simulation results were validated based on the results of a pressure transfer experiment. The findings of this study can serve as a reference for future research on nanoscale pore plugging with viscous flow.

Significance of the Microfluidic Flow Inside the Organ of Corti.

We study the vibration modes of a short section in the middle turn of the gerbil cochlea including both longitudinal and radial interstitial fluid spaces between the pillar cells (PC) and the sensory hair cells to determine the role of the interstitial fluid flow within the organ of corti (OoC). Three detailed finite element (FE) models of the cochlear short section (CSS) are studied. In model 1, the CSS is without fluids; model 2 includes the OoC fluid, but not the exterior scalae fluids; and model 3 is the CSS with both scalae and OoC fluids. We find that: (1) the fundamental mode shape of models 1 or 3 is similar to the classical basilar membrane (BM) bending mode that includes pivoting of the arch of corti, and hence determines the low frequency vibrational mode shape of the cochlea in the presence of the cochlear wave. (2) The fundamental mode shape of model 2 is characterized by a cross-sectional shape change similar to the passive response of the cochlea. This mode shape includes a tilting motion of the inner hair cell (IHC) region, a fluid motion within the tunnel of corti (ToC) in the radial direction and along the OoC, and a bulging motion of the reticular lamina (RL) above the outer hair cell (OHC). Each of these motions provides a plausible mode of excitation of the sensory hair cells. (3) The higher vibrational modes of model 1 are similar to the electrically evoked response within the OoC and suggests that the higher vibrational modes are responsible for the active response of the cochlea. We also observed that the fluid flow through the OoC interstitial space is significant, and the model comparison suggests that the OoC fluid contributes to the biphasic BM motion seen in electrical stimulation experiments. The effect of fluid viscosity on cilium deflection was assessed by performing a transient analysis to calculate the cilium shearing gain. The gain values are found to be within the range of experimentally measured values reported by Dallos et al. (1996, The Cochlea, Springer-Verlag, New York).

Effect of Fluid Viscosity on Earthquake Nucleation

AbstractInjection of fluids in geo‐reservoirs can reduce the effective stresses at depth, lubricating the nearby faults, promoting slip and, potentially, earthquakes. High‐viscous fluids are often used during hydraulic fracturing and production phases in geo‐reservoirs. Here, we performed dedicated experiments to study the influence of fluid viscosity on earthquake nucleation. We performed frictional sliding experiments at 30 and 50 effective normal stresses and fluids viscosity ranging from 1 to 1,226 mPa s and modeled them with a rate‐and‐state friction law. In the presence of fluid, the state variable is defined as the ability of the fluid to flow. Our results showed that static friction slightly decreases with increasing viscosity, the dynamic friction is governed by the dimensionless Sommerfeld number (S = 6ηVL/(σ'nH2)). Moreover, we observed that the (a − b) parameters of the rate‐and‐state friction law decrease with increasing viscosity down to (a − b) < 0, possibly promoting unstable slip and earthquake nucleation.

Research on Variation Law and Prediction Model of Working Viscosity of Salt Resistant Polymer

Using seepage experiments and theoretical methods, the effects of injection fluid viscosity and injection speed on the change of working viscosity of salt-resistant polymers in porous media with different permeability are studied. And developed a working viscosity prediction model. The results show that as the permeability and viscosity of the injection fluid increase, the working viscosity of the salt-resistant polymer in the porous medium increases; as the injection speed increases, the polymer exhibits viscoelasticity, and the working viscosity decreases first and then increases; under the same conditions, the working viscosity of the salt-resistant polymer is higher than that of the ordinary polymer; in the gray correlation analysis, the correlation coefficient of the injection fluid viscosity and working viscosity is 0.958, the permeability is 0.954, and the injection speed is 0.709; a multivariate statistical regression method is used to give a prediction model for the working viscosity of salt-resistant polymers. The average deviation between the predicted value and the actual calculated value is only 4.40%.

Fabrication of novel agarose–nickel bilayer composite for purification of protein nanoparticles in expanded bed adsorption column

In the present work, a novel agarose–nickel bilayer composite (ANBC) adsorbents modified with Cibacron Blue 3GA (CB3) dye-ligand were fabricated via the three-phase emulsion method. The surface morphology of the novel adsorbents was evaluated using an optical microscope, scanning electron microscopy, and atomic force microscopy. Also, the commercially purchased adsorbents were modified with the same ligand and compared to novel composite (ANBC-CB3). Also, Lactoferrin (Lf) nanoparticles synthesized and employed as a protein model. Residence time distribution experiments were performed to consider the effect of particle density and fluid viscosity. The results established that the ANBC-CB3 bilayer composite follows a typical size range of 60–300μm and a mean diameter of 125μm with a spherical appearance. In batch adsorption, ANBC-CB3 revealed a higher dynamic binding capacity (DBC) of Lf versus Streamline™-CB3. Furthermore, the experimental data were consistent with the Langmuir isotherm model. Finally, The DBC at 10% breakthrough and the two-fold flow rate was more than 70% for the novel adsorbent. It was proved that ANBC-CB3 as high selective adsorbents for protein nanoparticle purification is suitable for high flow rate operations in an expanded bed column.

Mass transfer in liquid-liquid Taylor flow in a microchannel: Local concentration distribution, mass transfer regime and the effect of fluid viscosity

Mass transfer characteristics of liquid-liquid Taylor flow with various fluid pairs are investigated, in order to reveal the viscous effects of the fluids. The concentration pattern in continuous slugs, mass transfer time and mass transfer coefficient are discussed and analyzed. Several different concentration patterns originated from recirculation are observed at both straight channels and curved bends, respectively. It is shown that the mass transfer coefficient (Ka and K) can increase with the increase in the viscosity of the continuous phase at large flow rates, which is explained by the increased contribution of the film at the lateral droplet side and its exchange with the bulk slug. Based on the dominance of different parts (i.e., film, cap), three mass transfer regimes are distinguished. Correlations for each regime, which covers a wide range of fluid viscosity of 0.89–45.6 mPa·s, are developed to predict the mass transfer coefficient.

Numerical Comparison for Focused Wave Propagation Between the Fully Nonlinear Potential Flow and the Viscous Fluid Flow Models

Numerical simulations on focused wave propagation are carried out by using three types of numerical models, including the linear potential flow, the nonlinear potential flow and the viscous fluid flow models. The wave—wave interaction of the focused wave group with different frequency bands and input wave amplitudes is examined, by which the influence of free surface nonlinearity and fluid viscosity on the related phenomenon of focused wave is investigated. The significant influence of free surface nonlinearity on the characteristics of focused wave can be observed, including the increased focused wave crest, delayed focused time and downstream shift of focused position with the increase of input amplitude. It can plot the evident difference between the results of the nonlinear potential flow and linear potential flow models. However, only a little discrepancy between the nonlinear potential flow and viscous fluid flow models can be observed, implying the insignificant effect of fluid viscosity on focused wave behavior. Therefore, the nonlinear potential flow model is recommended for simulating the non-breaking focused wave problem in this study.