Viscous Flow Behavior Research Articles

Synergistically using layered and fibrous organoclays to enhance the rheological properties of oil-based drilling fluids

Layered organo-montmorillonite (OMt) is widely used as the rheological additives in oil-based drilling fluids. Recently, fibrous organoclays, such as organo-palygorskite, had been reported as the rheological agent in oil-based drilling fluids. These organoclays showed different rheological properties and mechanisms. In this work, the joint use of OMt and OPal in oil-based drilling fluids was investigated. The optimized organoclays were prepared according to the previous reports and characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, thermal analysis. The rheological properties of mixed organoclays at different mass ratios were tested in comparison with the single organoclay. Viscous flow behavior, viscosity and thixotropy were summarized. The synergetic use of OMt and OPal could improve the rheological properties of oil-based drilling fluids, even aged at 200 °C. The optimal mass ratio of OMt to OPal was 1:1. The rheological mechanism of mixed OMt and OPal in oil was concluded based on the X-ray diffraction results of organoclay/oil gels. The presence of fibrous OPal enhanced the network structure of layered OMt and prevented the network structure from collapse by interlacing among the nanolayers.

Magnetohydrodynamic viscous fluid flow and heat transfer in a circular pipe under an externally applied constant suction

An analytical investigation of two-dimensional heat transfer behavior of an axisymmetric incompressible dissipative viscous fluid flow in a circular pipe is considered. The flow is subjected to an externally applied uniform suction over the pipe wall in the transverse direction and a constant magnetic field opposite to the wall. The reduced Navier-Stokes equations in the cylindrical system are applied for the velocity and temperature fields. Constant wall temperature is considered as the thermal boundary condition. The velocity components are expressed into stream function and its solution is acquired by the Homotopy analysis method (HAM). The effects of magnetic body force parameter(M), suction Reynolds number (Re), Prandtl number (Pr)and Eckert number (Ec) on velocity and temperature are examined and are presented in a graphical frame. Streamlines, isotherms and pressure contours are likewise pictured. It is observed that with increasing suction Reynold number decelerates axial flow, whereas it enhances the radial flow. The temperature distribution increases with an increase in Prandtl number, whereas it decreases with an increase in Eckert number (viscous dissipation effect).

Thermodynamic Analysis on Compressible Viscous Flow and Numerical Modeling Study on Piston/Cylinder Interface in Axial Piston Machine

The fluid film behavior in the lubricating gap between piston and cylinder bore in axial piston machines is the main focus of this paper. The thermal behavior of the compressible viscous flow in the thin lubricating film formed between piston and cylinder bore plays a critical role on the interface performance and energy dissipation, therefore, deserves a thorough analysis. The temperature distribution in the fluid domain, as well as the heat flux from the fluid domain to the solid domain, follow the first, and the second laws of thermodynamics, however, are difficult to solve due to the constantly changing boundary conditions. The proposed fluid domain thermodynamic model calculates temperature distribution in the gap flow and the heat flux to the solid parts with a higher accuracy than the currently used fluid domain heat transfer model.

A lubricant boundary condition for a biological body lined by a thin heterogeneous biofilm

We study the asymptotic behavior of an incompressible viscous fluid flow in a biological body lined by a thin biological film with a cellular microstructure, varying thickness, and a heterogeneous viscosity regulated by a time random process. Letting the thickness of the film tend to zero, we derive an effective biological slip boundary condition on the boundary of the body. This law relates the tangential fluxes to the tangential velocities via a proportional coefficient corresponding to the energy of some local problem. This law describes the ability of the biological film to function as a lubricant reducing friction at the wall of the body. The tangential velocities are functions of the random trajectories of a finely concentrated biological particle.

The hydrodynamic behavior of high viscous oil-water flow through horizontal pipe undergoing sudden expansion—CFD study and experimental validation

The main purpose of the present work is to study the hydrodynamic behavior of high viscous oil-water flow within the horizontal ducts undergoing sudden expansion. Computational fluid dynamic (CFD) approach by means of Volume of Fluid (VOF), encoded in Ansys Fluent 16.2 was applied and experimental validation was conducted. Characteristics of two-phase flow, such as pressure gradient, spatial distribution of phases (Hold-up) and flow regimes have been extracted.Three pipe configurations for sudden expansion (21–30 mm, 30–40 mm, and 30–50 mm) were selected. The major flow patterns under investigation included core-annular (CAF) and transition from CAF to dispersed flows, with twelve cases considered for numerical runs. The presence of sudden expansion caused the oil core to become more eccentric and thicker far from singularity and without oil contact at the pipe wall during core-annular flow. This is consistent with the flow visualizations that were observed experimentally and discussed in details in the current paper.

Effect of various plasticisers on viscous flow properties of natural pozzolanic cement pastes

The effect of various plasticisers (lignosulfonates and copolymers) on volcanic cement was assessed in this study. The volcanic cement was designed by substituting Portland cement with a natural volcanic pozzolan resulting from Andean volcanic activity. The best results (i.e. the volcanic cement pastes that showed shear-thickening viscous flow behaviour) were obtained when the zero-shear viscosity, minimum viscosity and shear rate for the onset of shear-thickening behaviour showed dependency on the paste concentration, Portland cement substitution and plasticiser concentration. The results were verified by the distorting effect of solid particles on the flow field.

Unusual flow behavior of Fe-based soft magnetic amorphous ribbons under high temperature tensile loading

The viscous thermal flow behavior and mechanical property of [Fe0.6Co0.15B0.2Si0.05] (100−x)Tax (x = 0, 1, 2, 3, 4, and 5) soft magnetic amorphous ribbons were studied. The characteristics of melt-spun amorphous ribbons were measured by using vibration sample magnetometer (VSM), nanoindentation, differential scanning calorimetry (DSC) and thermo-mechanical analysis (TMA) to study the effects of Ta content variation on the thermal stability, mechanical, and soft magnetic properties. We observed that the nanoindentation hardness, Young's modulus, and glass transition and crystallization temperatures were improved by the addition of Ta. Using dilatometry measurement, TMA, by heating at a constant rate under tension mode, we examined not only the glass transition and crystallization behaviors but also the possibility of coexistence of multiple amorphous phases.

Viscous Flow Behaviour of Karanja Oil Based Bio-lubricant Base Oil.

Karanja oil (KO) is widely used for synthesis of bio-fuel karanja oil methyl ester (KOME) due to its competitive price, good energy values and environmentally friendly combustion properties. Bio-lubricant is another value added product that can be synthesized from KO via chemical modification. In this work karanja oil trimethylolpropane ester (KOTMPE) bio-lubricant was synthesized and evaluated for its viscous flow behaviour. A comparison of viscous flow behaviours of natural KO and synthesized bio-fuel KOME and bio-lubricant KOTMPE was also made. The aim of this comparison was to validate the superiority of KOTMPE bio-lubricant over its precursors KO and KOME in terms of stable viscous flow at high temperature and high shear rate conditions usually encountered in engine operations and industrial processes. The free fatty acid (FFA) content of KO was 5.76%. KOME was synthesized from KO in a two-step, acid catalyzed esterification followed by base catalyzed transesterification, process at 65°C for 5 hours with oil-methanol ratio 1:6, catalysts H2SO4 and KOH (1 and 1.25% w/w KO, respectively). In the final step, KOTMPE was prepared from KOME via transesterification with trimethylolpropane (TMP) at 150°C for 3 hours with KOME-TMP ratio 4:1 and H2SO4 (2% w/w KOME) as catalyst. The viscosity versus temperature studies were made at 0-80°C temperatures in shear rate ranges of 10-1000 s-1 using a Discovery Hybrid Rheometer, model HR-3 (TA instruments, USA). The study found that viscosities of all three samples decreased with increase in temperature, though KOTMPE was able to maintain a good enough viscosity at elevated temperatures due to chemical modifications in its molecular structure. The viscosity index (VI) value for KOTMPE was 206.72. The study confirmed that the synthesized bio-lubricant KOTMPE can be used at high temperatures as a good lubricant, though some additives may be required to improve properties other than viscosity.

Steady viscous flow of some commercial Andean volcanic Portland cement pastes

Three commercial Ecuadorian cements, obtained from crushing a mix of clinker and a mixture of pumice powder and volcanic ash, were selected to perform studies on steady viscous flow behaviour. Steady flow curves were obtained during the dormant period. All pastes showed non-linear viscoplastic behaviour. A modified Bingham model was fitted to the experimental data. The yield stress was found to increase and plastic viscosity decreased with clinker substitution. These results were justified by using a model that considers fresh volcanic cement paste as a suspension of particles (cement and volcanic powder) dispersed in a liquid phase, formed by water, and a gel part, formed from the cement–water chemical reaction.

Influence of spherical particles and interfacial stress distribution on viscous flow behavior of Ti‐Cu‐Ni‐Zr‐Sn bulk metallic glass composites

Bulk metallic glass composites containing micro-scale B2 particles are subject to investigation with regards to the influence of B2 particles and interfacial stress and strain distribution on the viscous flow behavior at a super-cooled liquid state. An increased volume fraction of B2 particles leads to an increase of minimum viscosity and influences viscous flow behavior before crystallization. In high temperature deformation, the bulk metallic glass shows homogeneous deformation feature. However, the heterogeneous deformation feature is found in thermoplastically deformed bulk metallic glass composite. The strong stain accumulation and sluggish viscous flow occur around B2 particles, which are caused by the heterogeneous stress distribution linked to stress concentration and shear stress impediment around B2 particles. The sluggish viscous flow of super-cooled liquids around B2 particles during high temperature deformation induces an increase of viscosity and strongly affects the viscous flow behavior of Ti-based bulk metallic glass composites containing micro-scale spherical B2 particles.

Prediction of heating rate controlled viscous flow activation energy during spark plasma sintering of amorphous alloy powders

The viscous flow behavior of Fe-based amorphous alloy powder during isochronal spark plasma sintering was analyzed under the integrated theoretical background of the Arrhenius and directional structural relaxation models. A relationship between viscous flow activation energy and heating rate was derived. An extension of the pertinent analysis to Ti-based amorphous alloys confirmed the broad applicability of such a relationship for predicting the activation energy for sintering below the glass transition temperature (Tg) of the amorphous alloy powders.

Anisotropic hydrodynamic turbulence in accretion disks

Recently, the vertical shear instability (VSI) has become an attractive purely hydrodynamic candidate for the anomalous angular momentum transport required for weakly ionized accretion disks. In direct three-dimensional numerical simulations of VSI turbulence in disks, a meridional circulation pattern was observed that is opposite to the usual viscous flow behavior. Here, we investigate whether this feature can possibly be explained by an anisotropy of the VSI turbulence. Using three-dimensional hydrodynamical simulations, we calculate the turbulent Reynolds stresses relevant for angular momentum transport for a representative section of a disk. We find that the vertical stress is significantly stronger than the radial stress. Using our results in viscous disk simulations with different viscosity coefficients for the radial and vertical direction, we find good agreement with the VSI turbulence for the stresses and meridional flow; this provides additional evidence for the anisotropy. The results are important with respect to the transport of small embedded particles in disks.

Thermo-mechanical study of rapidly solidified NiNbZrTiAl amorphous metallic alloys

The thermal stability and viscous flow behaviour of fourrapidly solidified NiNbZrTiAl amorphous metallic alloys under constant heating rate conditions are studied using thermomechanical analyzer (TMA). The viscous flow results are discussed and interpreted in the framework of the Free Volume Model (FVM). The obtained values of FVM parameters are used for estimation of the glass forming ability (GFA) on the basis of the parameter of Angell. The lowest value of Angell's parameter mA (highest GFA) possesses the alloy Ni58Nb10Zr13Ti12Al7. The fracture strength of the alloys studied was estimated on the basis of their correlation with the alloys glass transition temperature Tg according to the equation of Yang. It was determined that the maximum fracture strength possesses the alloy Ni58Nb25Zr8Ti6Al3.

Investigation on Viscosity and Nonisothermal Crystallization Behavior of P-Bearing Steelmaking Slags with Varying TiO2 Content

The viscous flow and crystallization behavior of CaO-SiO2-MgO-Al2O3-FetO-P2O5-TiO2 steelmaking slags have been investigated over a wide range of temperatures under Ar (High purity, >99.999 pct) atmosphere, and the relationship between viscosity and structure was determined. The results indicated that the viscosity of the slags slightly decreased with increasing TiO2 content. The constructed nonisothermal continuous cooling transformation (CCT) diagrams revealed that the addition of TiO2 lowered the crystallization temperature. This can mainly be ascribed to that addition of TiO2 promotes the formation of [TiO6]-octahedra units and, consequently, the formation of MgFe2O4-Mg2TiO4 solid solution. Moreover, the decreasing viscosity has a significant effect on enhancing the diffusion of ion units, such as Ca2+ and [TiO4]-tetrahedra, from bulk melts to the crystal–melt interface. The crystallization of CaTiO3 and CaSiTiO5 was consequently accelerated, which can improve the phosphorus content in P-enriched phase (n2CaO·SiO2-3CaO·P2O5). Finally, the nonisothermal crystallization kinetics was characterized and the activation energy for the primary crystal growth was derived such that the activation energy increases from −265.93 to −185.41 KJ·mol−1 with the addition of TiO2 content, suggesting that TiO2 lowered the tendency for the slags to crystallize.

Universality in the non-Newtonian viscous flow behavior of AsxSe1 − x liquids: Results from capillary rheometry

The shear rate dependence of the viscosity of AsxSe1−x (5≤x≤40) liquids is studied using capillary rheometry. All liquids display non-Newtonian rheological behavior in the form of shear thinning. The onset of such behavior is characterized by shear rates that are nearly four orders of magnitude slower than the average rate of structural relaxation. Proper normalization of the viscosity vs. shear rate data demonstrates a remarkable universality in this behavior, irrespective of chemical composition, structure, topology and temperature. The existence of such universality suggests an underlying commonality in the fundamental atomistic mechanism of shear thinning in these chalcogenide liquids.

High aspect ratio grating by isochronal imprinting of less viscous workable Gd-based metallic glass for neutron phase imaging

Metallic glass (MG) exhibits viscous flow behavior in the supercooled liquid (SCL) state, which is of great advantage for its net-forming process. However, the viscous workability varies strongly with the alloy system and/or composition. In this paper, we demonstrate how MG with less viscous workability such as Gd-based MG can be processed in the SCL region. Based on this understanding, high aspect ratio analyzer gratings of 9 μm pitch and ∼30 μm heights have been fabricated through an imprinting method by allowing crystallization during a rapid heating isochronal imprinting process. The analyzer gratings made of Gd-based MG have brought a breakthrough for advancing neutron phase imaging based on grating interferometer.

Analysis of viscous flow properties of asphalt in aging process

The inevitable change in asphalt properties owing to aging exists in the cycle of pavement decay under the loading from both weather and traffic. To analyze the viscous flow properties of asphalt in the aging process, a series of aging simulation tests were conducted on five regular asphalt samples for different time by rolling thin film oven (RTFO) in the laboratory, and then Brookfield rotational viscosity (RV), dynamic shear rheological test (DSR), bending beam rheometer (BBR) and component analysis (CA) tests were carried out on these samples. The parameter visco-flow activation energy (Eη) was obtained by means of Arrhenius equation according to the viscosity values of asphalt at different temperatures. The changing regularity of Eη during the aging process was analyzed. On the base of DSR, BBR and CA test result analysis, the relationship of Eη with G∗sin δ, tan δ, m-value and Ic was discussed respectively. The results and analysis indicate there is significant effect of aging on viscous flow behavior of asphalt. With the deepening of aging, Eη increases continuously. The average growth rate of Eη for the same asphalt in several aging stages varies considerably due to the difference in anti-aging performance. There is no remarkable relationship between Eη and DSR rheological parameters, while Eη shows a good negative correlation with the rate of creep stiffness (m) and also a good linear correlation with colloidal instability index (Ic). Therefore, the viscous flow property of asphalt is closely related to the low temperature creep behavior and colloidal structure.

Thermo-mechanical study of bulk glass forming Zr-Cu-Ni-Al alloys

The thermal stability and viscous flow behavior of bulk glass forming Zr68Cu13Ni11·5Al7.5 and Zr69Cu12·5Ni11Al7.5 alloys are studied. The viscosity experimental results are interpreted based on the free volume model (FVM). The values of the obtained model parameters are used to estimate the glass forming ability (GFA) in terms of Angell parameter, and the fracture strength of the alloys based on its correlation with the glass transition temperature (Tg). The viscosity data are compared with DSC measurements. The two glasses, having similar composition, revealed comparable Tg, but one of them (Zr68Cu13Ni11·5Al7.5) showed substantially lower crystallization temperature due to quasicrystals formation. Higher GFA was obtained for Zr69Cu12·5Ni11Al7.5 alloy.

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

Viscous Flow and Crystallization Behaviors of P-bearing Steelmaking Slags with Varying Fluorine Content

Injectable surgical sealant for controlled cell delivery and fusion of cartilage-to-cartilage interfaces

Event Abstract Back to Event Injectable surgical sealant for controlled cell delivery and fusion of cartilage-to-cartilage interfaces Ashkan H. Tehrani1, 2, Sumrita Bhat1, 2, Neil A. Duncan2, 3 and Arindom Sen1, 2 1 University of Calgary, Pharmaceutical Production Research Facility, Department of Chemical and Petroleum Engineering, Canada 2 University of Calgary, McCaig Institute for Bone and Joint Health, Canada 3 University of Calgary, Department of Civil Engineering, Schulich School of Engineering, Canada Introduction: Since the development of the first generation of cell-based therapies, autologous chondrocyte implantation (ACI) and mesenchymal stem cell transplantation have been used in clinical trials for joint repair[1]. However, a major challenge is the difficulty of the surgical procedure to deliver cells to the site of injury. In ACI, for example, surgeons utilize a periosteal flap to secure the cell-implant, and a high cell density to make up for hypertrophy[2]. During the culture, dedifferentiation and loss of phenotype constitute an added complexity. In this study, we introduce a novel injectable system that (i) serves as a safe vehicle for controlled cell delivery, (ii) possesses a degree of adhesiveness to confine cell to the defect site at the time of implantation, and (iii) exhibits a tunable mechanical environment to drive the commitment of the cells toward the desired lineage. This system must (i) be injectable, (ii) adhere to the chondral interface, and (iii) sustain cell release over time without compromising the level of repair. Materials and Methods: The proposed hydrogel system consisted of a crosslinked and a non-crosslinked domain. The proportion of the former impacts the mechanical environment in which the cells reside, the injectability of the system and the degree of adhesiveness, while the latter determines cell release rate. A 3% alginate/polyethylene glycol solution (1:3) was prepared in PBS at 60°C overnight followed by internal gelation during vortex with 1% calcium solution at room temperature. Porcine chondrocytes were mixed at a density of 1×106 cell/mL with the gel, and injected in a 3 mm circular defect model in a porcine patella in vitro. External gelation took place in a bath of 5% calcium solution immediately after the injection. Samples were incubated at 37°C with PPRF-MSC6 medium[3], in 5% CO2 until the completion of the delivery phase. Results and Discussion: The results showed that the gel demonstrated a viscous flow behavior at the time of injection to effectively penetrate throughout the cylindrical defect models and fully embed the implantation site, then demonstrated solid-like properties in situ post external gelation with adequate mechanical stability to not flow from the defect vicinity (Fig 1). Also, the gel was able to completely fill the focal defect model, fuse with the surrounding cartilage tissue (Fig 2a), and seal the implantation site flush to the articular surface (Fig 2). There was no need for additional fixation such as patches since the sealant demonstrated ample resistance to peeling off from the superficial layer. Figure 3 shows how the cells were released at a controlled rate due to the spontaneous discharging of the non-crosslinked domain which resulted in the concomitant breakdown of the matrix by day 7. As the release rate increased with time, the gel strength decreased and cell migration accelerated (Fig 3). Conclusion: This research introduced an injectable sealant, which also served as a cell delivery vehicle and an adhesive to treat chondral defects of different size and shape. By design, it represented a multifunctional mimicry of the chondrocytes niche in cartilage since it encompassed cells in a three-dimensional matrix, under a hypoxic condition and with a relatively similar mechanical environment to that of native cartilage. From a surgical viewpoint, the system can be cured in situ within seconds and demonstrated a reliable and a cost-effective additional step that can benefit various cell-based therapies. Alberta Innovates: Health Solutions; Natural Sciences and Engineering Research Council of Canada (NSERC)