Theoretical Analysis of Plastic Forming Process for Semi-Solid Material

Disengagement of dispersed cerium oxalate from nitric-oxalic acid medium in a batch settler: Measurements and CFD simulations

Investigating the thermal properties of single-grade engine oil (SAE 50) with the simultaneous addition of MWCNT and CuO nanoparticles

In this study, the preparation of nanofluid (NF) is performed by the two-stage method by dispersing nanoparticles (NP) into the base fluid (BF). Hybrid nanofluids (HNFs) were prepared in the solid volume fractions (SVFs) of SVF = 0.1, 0.2, 0.3, 0.4 and 0.5% and mono nanofluids (MNFs) were made in SVF = 0.1 and 0.3%. After ensuring stability, the thermal conductivity (TC) of HNFs and MNFs is measured by the hot wire method at a temperature range of T = 20–60 °C. The results indicate that the TC (For HNFs and MNFs) increases as the temperature increases. Increasing the SVF also increases TC, which is more evident in the higher SVFs. According to the obtained results, the highest increase in the TC is related to the MWCNT-CuO-cerium oxide/water HNF in SVF = 0.5% and T = 60 °C, which is a 26.7% increase compared to BF. In SVF = 0.3%, the MNFs containing MWCNTs NPs have a better performance than the HNFs. Compared to the results with the relationship of Lu-Lin, it was found that the temperature is critical in increasing the TC. There are no temperature parameters in the Lu-Lin model, therefore there is a difference between the laboratory results and the Lu-Lin model results. Finally, based on experimental data, a mathematical relationship between temperature and SVF was proposed to predict the TC for HNF water/cerium oxide-CuO-MWCNT. Comparing the experimental data to the outputs of the proposed relationship shows that this relationship is accurate.

Optimization of response function on hydromagnetic buoyancy-driven rotating flow considering particle diameter and interfacial layer effects: Homotopy and sensitivity analysis

Verkhnechonskoe oil field is situated in Eastern Siberia, Russia. This field is quite unique due to low formation temperatures –the bottom hole static temperature does not exceed 13 degC. This low temperature environment together with low formation fracture gradient present unique challenges for cementing operation. Conventional lightweight system extended by sodium silicate does not meet client well acceptance criteria – no sustained casing pressure (SCP) and successful annular space pressure test due to delayed compressive strength development and relatively high permeability of set cement stone. Failure to meet those criteria’s result in remedial cementing operations and delay of putting wells in production. To overcome this challenge new lightweight cement system based on optimized particles size distribution is successfully introduced for primary cementing of production casing on Verkhnechonskoe field. Implementation of the novel lightweight cement system with high solid volume fraction has allowed client to overcome highlighted issues. Rapid compressive strength development also helped in reduction of well construction time due to shorter wait-on-cement period. This paper outlines an approach based on the usage of optimized particles size distribution lightweight cement system in low temperature environment included three steps of cementing operation: design of cement system, implementation and evaluation results.

Microstructure quantification procedures in liquid-phase sintered materials

A new and efficient direct numerical method with second-order convergence accuracy was developed for fully resolved simulations of incompressible viscous flows laden with rigid particles. The method combines the state-of-the-art immersed boundary method (IBM), the multi-direct forcing method, and the lattice Boltzmann method (LBM). First, the multi-direct forcing method is adopted in the improved IBM to better approximate the no-slip/no-penetration (ns/np) condition on the surface of particles. Second, a slight retraction of the Lagrangian grid from the surface towards the interior of particles with a fraction of the Eulerian grid spacing helps increase the convergence accuracy of the method. An over-relaxation technique in the procedure of multi-direct forcing method and the classical fourth order Runge-Kutta scheme in the coupled fluid-particle interaction were applied. The use of the classical fourth order Runge-Kutta scheme helps the overall IB-LBM achieve the second order accuracy and provides more accurate predictions of the translational and rotational motion of particles. The preexistent code with the first-order convergence rate is updated so that the updated new code can resolve the translational and rotational motion of particles with the second-order convergence rate. The updated code has been validated with several benchmark applications. The efficiency of IBM and thus the efficiency of IB-LBM were improved by reducing the number of the Lagragian markers on particles by using a new formula for the number of Lagrangian markers on particle surfaces. The immersed boundary-lattice Boltzmann method (IBLBM) has been shown to predict correctly the angular velocity of a particle. Prior to examining drag force exerted on a cluster of particles, the updated IB-LBM code along with the new formula for the number of Lagrangian markers has been further validated by solving several theoretical problems. Moreover, the unsteadiness of the drag force is examined when a fluid is accelerated from rest by a constant average pressure gradient toward a steady Stokes flow. The simulation results agree well with the theories for the short- and long-time behavior of the drag force. Flows through non-rotational and rotational spheres in simple cubic arrays and random arrays are simulated over the entire range of packing fractions, and both low and moderate particle Reynolds numbers to compare the simulated results with the literature results and develop a new drag force formula, a new lift force formula, and a new torque formula. Random arrays of solid particles in fluids are generated with Monte Carlo procedure and Zinchenko's method to avoid crystallization of solid particles over high solid volume fractions. A new drag force formula was developed with extensive simulated results to be closely applicable to real processes over the entire range of packing fractions and both low and moderate particle Reynolds numbers. The simulation results indicate that the drag force is barely affected by rotational Reynolds numbers. Drag force is basically unchanged as the angle of the rotating axis varies.

The impacts of the solid volume fraction Vs and particle size dp on the total and local gas holdups in gas‐liquid‐solid bubble columns under different flow regimes were investigated. The flow regimes discussed were the discrete bubble regime (DBR), transition regime (TR), bubble coalescence regime (BCR), and strong turbulent regime (STR). The results demonstrated that the bed average gas holdup εg decreased with higher solid volume fraction in DBR, TR, and BCR. The increment of the solid volume fraction promoted bubble coalescence and also can enhance the particle effect on the average gas holdup. The εg changed slightly when shifting the Vs or dp in STR. A new correlation for εg was developed considering the particle properties and the flow regimes studied.

This report presents the three-dimensional electromagnetohydrodynamic flow of a zinc-oxide–water nanofluid past a bidirectional Riga plate with velocity slips and thermal and mass convection conditions. The Cattaneo–Christov heat and mas flux model, thermal radiation, chemical reaction and activation energy are considered to analyze the flow problem. The volume fraction of the ZnO nanoparticles is taken 6% in this analysis. An appropriate set of similarity variables is used to transform the partial differential equations into ordinary differential equations. During this process, some parameters are found and influences of these factors on the flow profiles are shown and discussed in detail. A numerical technique called NDSolve is considered for the solution of the nanofluid flow problem. The results showed that higher solid volume fraction and slip parameter have reduced velocities profiles and the increasing solid volume fraction and thermal Biot number have increased the temperature profile. Additionally, the concentration Biot number has increased the concentration profile. The modified Hartmann number has significantly increased the velocity profile. Dual impacts in velocity profiles along primary and secondary direction has been observed due to stretching ratio parameter. A comparison of current results has been carried with a fine agreement amongst current and established results.

The flow behavior of native corn and potato starch granule suspensions prepared in a concentrated sucrose solution has been investigated. Measurements were performed using a rotational rheometer with a concentric cylinder geometry. Starch suspensions were dilute to semi-concentrated (1 % to 25 % by volume). Shear and dynamic viscosity were measured by shear flow and dynamic oscillatory testing at 20, 50 and 80 °C. The starch suspensions exhibited essentially Newtonian behavior at all solid contents, although at higher solid volume fractions there was evidence of slight shear thickening. The relative viscosity of suspensions increased with increasing starch granule content, and the data conformed well to Maron-Pierce’s equation. An increase in maximum packing fraction and gravitational depletion of the starch granules with increasing temperature resulted in lower relative viscosities at higher temperatures. Also, the relative viscosities of potato starch granule suspensions with bigger, more oval and anisometric particles were lower than those of corn starch suspensions where granules were closer to sphericity but were angular in shape. Oscillatory shear testing results showed the presence of viscoelastic properties at intermediate solid volume fractions at low frequencies; in addition, the relative shear viscosity was higher than the relative dynamic viscosity, probably due to the formation of shear-induced structures during the shear flow test.

Wear mechanism investigation in a centrifugal slurry pump impeller by numerical simulation and experiments

A number of processes for fabricating dense, solid materials begin with a solid powder that is to be fashioned--without melting--into an article with a particular geometric shape. Moreover, it is often the case that the small, discrete particles are dispersed in a continuous liquid phase, such as in ceramic slips, filled molten polymers, as well as suspensions used in some powder metallurgy and composite fabrication processes. Further, in these cases it is often the flow behavior or deformability of the solid-liquid suspension that is of central importance in a particular materials fabrication process, since such operations as mold-filling, pressing, extrusion, transport through pipes and channels, and even some mixing and separation processes, must take advantage of certain of the rheological characteristics of the suspension. In particular, it is the fact that such suspensions possess distinctly fluid-like properties (that is, even though they may contain a significant amount of a non-fluid-like solid phase) which allows them to be deformed. Difficulties arise, of course, as the volume fraction of the dispersed solid phase is increased, since in this case the suspension behaves like a fluid with a viscosity that is significantly higher than that of the liquid alone. For a variety of reasons, of course, it is desirable to use a suspension with a high volume fraction of solids (φs)--such as in shape-forming operations where the goal is to prepare a shaped article with a high solids volume fraction--even though the suspension’s high “viscosity” makes that shape-forming operation more difficult. What is needed, of course, is a detailed, quantitative knowledge of the relationship between φs and the “viscosity” of a given suspension, for a variety of flow conditions, in order to design a shape-forming process, or perhaps to improve an existing one.

Solid volume fraction is a defining characteristic of multiphase gas–solid flows. In the case of gravity-driven particle curtains, it changes significantly along the flow direction. This has implications for the performance of falling-particle solar receivers, which use particle curtains to capture and store heat from concentrated sunlight. This study reports on the characterization of solid volume fraction as a function of height in gravity-driven particle curtains using optical techniques and simulations performed with a discrete element method (DEM) model. The experimental domain is a hopper-fed vertical channel, and the modeling domain is designed to match the experimental setup. Solid volume fraction was obtained from experimentally measured transmittance using two techniques: (1) a thermopile detector paired with a visible light source and (2) a high-speed camera. The DEM simulations were calibrated by identifying the coefficient of static friction between particles that resulted in equivalent mass flow rates to the experiments. All techniques, including an analytical model derived from first principles and empirical relationships, showed very similar trends of solid volume fraction decreasing along the flow direction, where it drops off rapidly initially before leveling off in a power law relationship. Both experimental and computational tests were performed with 1 mm and 2 mm particles, and solid volume fraction is found to decrease with increasing particle size at any location in the channel. Furthermore, the solid volume fractions calculated from transmittance measurements were found to be sensitive to the optical properties of the particles through Monte Carlo ray tracing simulations. To account for this effect, a new scale factor dependent on particle reflectivity is derived, which leads to significantly improved agreement between experimental and simulated results. A simple, closed-form equation is proposed to transform measured transmittance to a solid volume fraction while accounting for particle reflectivities. Even though solid volume fractions above 0.1 were not measured in this study, the technique developed is suitable to measure even larger solid volume fractions, especially for more reflective particles.

This paper outlines an innovative approach to optimize workover re-entry wells eliminating the liner and tie-back operations by addressing challenges that had placed this strategy as not suitable in the previous history of the onshore operations around the area. The main concern deemed impossible was cementing a 7″ Production Casing from the landing point to the surface safely and successfully. This strategy is essential for the development of the field and to efficiently deliver the well count on time. The project started by designing and selecting the casing materials, required auxiliary equipment and mitigating all the risks associated with the equivalent circulating density (ECD) during drilling and cementing and refining operational procedures, the projected provided a more operationally efficient well, in a shorter time, lower cost and a more integral well with not weak points as the tie-back connections and the stage tool ports. This technique eliminates the need for running and cementing both a 7″ liner and a tieback, streamlining the process while ensuring uncompromised well isolation. Hydraulic simulation, drawing from available field data, was employed to assess acceptable equivalent circulating densities (ECDs) and pressures without risking losses. These simulations guided the refinement of cement slurry designs. A specialized lightweight cement system was suggested to address ECD margin limitations and challenges linked with conventional lightweight cement. Additionally, an expandable gas-tight system was introduced to prevent zonal communication and micro annulus in between the different reservoirs. Further enhancements included the introduction of sealing/bridging spacer to ensure effective mud removal along with the optimization of pumping rates to minimize losses during displacement. Optimized pumping rates during drilling, well bore cleaning and conditioning and cementing operations were guided by simulation data to ensure that dynamic pressures remained safely below fracture pressure thresholds. Additionally, it was decided to include higher density mud to assist in reducing surface pressures during the displacement. The utilization of a specialized lightweight slurry proved effective in decreasing hydrostatic pressure of the fluid column, thereby preventing lost circulation incidents and guaranteeing a positive indication of cement return to the surface. The drilling fluids conditioning, the spacers train and the exceptional rheology of the slurry facilitated improved mud displacement and enhanced cement coverage during placement. Furthermore, a higher solid volume fraction (SVF) in the cement contributed to reduced porosity and permeability, ensuring long-term zonal isolation and casing protection, thereby minimizing maintenance requirements and extending the well's lifespan, especially in critical reservoirs. The expandable property of the set cement mitigates for any potential micro annulus development, helping to avoid sustained casing pressure (SCP) complications throughout the well's operational life, thus reducing the need for further remedial cementing operations. Moreover, a specialized spacer system efficiently aided in mud removal and demonstrated excellent bonding, as confirmed by cement evaluation logs (CEL) conducted across the 7″ casing. This comprehensive design approach effectively eliminated additional operational costs and rig time by circumventing the necessity for further remedial interventions. This paper aims to showcase the utilization of 7″ production casing in conjunction with specialized cement design as an efficient substitute for conventional liners and tiebacks. The goal is to reduce rig costs and save time during workover re-entry wells, while also minimizing the need for future costly remedial works.

A three-dimensional multilayer shallow water approach to study polydisperse sedimentation and sediment transport in a viscous fluid is presented. The fluid is assumed be loaded with finely dispersed solid particles that belong to a finite number of species that differ in density and size. The model formulation allows one to recover the global mass and linear momentum balance laws of the mixture. The model incorporates compressibility of the sediment and viscosity of the mixture through a viscous stress tensor. As a consequence of a dimensional analysis applied to the global mass conservation and linear momentum balance equations, the horizontal components of the compression term and the horizontal terms of the viscous stress tensor may be neglected. This results in a final model that is vertically consistent with the classical one-dimensional vertical model. Numerical simulations illustrate the coupled solids volume fraction and flow fields in various scenarios and the effect of the compressibility and viscosity terms. Various bottom topographies give rise to recirculation of the fluid and high solids volume fractions on the bottom.