The parameters of jet mixing devices have an important influence on the mixing process, particle movement and interface regulation. At present, jet mixing devices are widely used in the coal slime flotation field, and their variable parameters lack systematic optimization. In this paper, the performance of reagent mixing and the distribution characteristics of flow field are taken as the evaluation indexes, and computational fluid dynamics (CFD) software (FLUENT) is used to optimize the variable parameters of the device. The results show that when the area ratio Ar=1.96~3.24, the throat-nozzle distance Le=0.2Dh~0.6Dh, the suction tube is located 1/4~1/2 Lz to the left of the nozzle outlet and is symmetrically arranged, the length of the throat tube L is from 6Dz to 12Dz, the mixing performance of the jet mixing device was optimal. The flow field distribution characteristics showed that the area ratio has a more significant effect. The larger the area ratio is, the more favorable the mi... [more]

This study used Computational Fluid Dynamics (CFD) to simulate and analyze the working fluid in magnetic centrifugal refrigerant compressors using R-134a to mixed refrigerant: R-513A and HFO (Hydrofluoroolefins) Hydrofluoroolefin refrigerant: R-1234yf, and the impact on integrated part-load performance, Integrated Part Load Value (IPLV) and internal flow field. This study used a single-stage 280 USRT maglev centrifugal refrigerant compressor as a simulation model. Three different refrigerants were used: R-134a, R-513A, and R-1234yf, as presented in the National Institute of Standards and Technology (NIST) real gas database. The refrigerant was used to set the IPLV working conditions and change the compressor speed and mass flow rate to simulate the compressor’s characteristic curve after replacing the refrigerant. The compressor working conditions were the fixed refrigeration cycle condensation and evaporation following the same capacity standards. This study used the CFD software by A... [more]

The generalized multifluid modelling approach (GEMMA) has been developed to handle the multiplicity of flow regimes and the coexistence of interfaces of largely different scales in multiphase flows. The solver, based on the OpenFOAM reactingEulerFoam family of solvers, adds interface resolving-like capabilities to the multifluid solver in the cells occupied by large interfaces. In this paper, GEMMA is further developed to predict stratified and slug flow regimes in horizontal ducts. The suppression of the turbulence and the wall-like behaviour of large interfaces is modelled with an additional dissipation source. This enables an accurate prediction of the velocity and of the turbulence kinetic energy in a stratified channel flow and the capturing of the formation and the travel of liquid slugs in an annulus. Large interfaces are identified and tracked, not only in the smooth and wavy stratified regimes but also in the much more perturbed interfaces of liquid slugs. The present work con... [more]

Numerical investigations have been carried out for a postulated enclosure fire scenario instigated due to methanol pool ignition in a chemical cleaning facility. The pool fire under consideration is radiation-dominated and poses a risk to the nearby objects if appropriate safety requirements are not met. The objective of the current study was to numerically evaluate the postulated fire scenario and provide safety recommendations to prevent/minimize the hazard. To do this, the fire scenario was first modeled using the finite volume method (FVM) based solver to predict the fire characteristics and the resulting changes inside the enclosure. The FDS predicted temperatures were then used as input boundary conditions to conduct a three-dimensional heat transfer analysis using the finite element method (FEM). The coupled FVM−FEM simulation approach enabled detailed three-dimensional conjugate heat transfer analysis. The proposed FVM−FEM coupled approach to analyze the fire dynamics and heat... [more]

Tailings storage facilities (TSFs) are known as a time-bomb. The numerous failures of TSFs and the heavy catastrophic consequences associated with each failure of TSFs indicate that preventing measures are necessary for existing TSFs. One of the preventing measures is to construct catch dams along the downstream near TSFs. The design of catch dams requires a good understanding of the dynamic interaction between the tailings slurry flow and the catch dams. There are, however, very few studies on this aspect. In this study, a numerical code, named LS-DYNA, that is based on a combination of smoothed particle hydrodynamics and a finite element method, was used. The numerical modeling shows that the tailings slurry flow can generally be divided into four stages. In terms of stability analysis, a catch dam should be built either very close to or very far from the TSF. When the catch dam with an upstream slope of a very small inclination angle is too close to the tailings pond, it can be nece... [more]

Due to fracture interference, not all perforations can be fractured, resulting in 20% of fractures contributing to 80% of the total production. The extraction of oil and gas also reduces production, necessitating refracturing. In this study, the finite element method was used to simulate multiple fractures fracturing simultaneously and the stress field distribution was then extracted and applied to a new geological model. This paper explains the effect of stress around the horizontal wellbore on new fractures during the refracturing of old wells using a temporary plugging technique. The results show that initial breaking pressures are the same, but as fractures extend, inter-fracture interference increases, resulting in different fracture extension pressures and widths. The fracturing fluid is filtered into the reservoir matrix after fracturing, reducing formation stress. Compared with fracturing at the initial fracture site, reperforating fracturing has a lower fracture extension pres... [more]

Microwave-driven electrodeless ultraviolet (UV) lamps have the advantages of high efficiency and high power. However, the conventional microwave system is slightly oversized, which restricts the use of the lamp in a narrow space. A miniaturized microwave-driven electrodeless UV lamp based on a coaxial slot antenna was developed in this study. First, the structure of slots was optimized using a finite-difference time-domain algorithm such that high efficiency of radiated energy could be achieved. Second, a complex model based on the Drude model and the electromagnetic theory was established to simulate the interaction between the microwave and UV lamps. The efficiency and uniformity of the UV lamps were analyzed. Finally, an experimental system was built, and the computed results agreed well with the simulation results. The efficiency of the miniaturized microwave-driven electrodeless UV lamp reached 91.8%.

A new dynamic air classifier was designed to address the problems of uneven material dispersion and high dust concentration in industrial applications of turbo air classifiers. This paper presents a study on the use of guide cones in the new dynamic air classifier. The ANSYS-Fluent 19.2 software was implemented to simulate the airflow in the dynamic air classifier, and the impact of the guide cone size on the flow field and classification performance of the dynamic air classifier was investigated. The simulation results indicated that with the increase in the guide cone height, the flow field distribution becomes reasonable and the velocity distributions become uniform. When the guide cone height is greater than twice the distance between the guide cone and the bottom of the rotor cage, there is no discernible change in the flow field distribution and classification efficiency. When the guide cone diameter is approximately 0.9 times the diameter of the rotor cage, the airflow pathline... [more]

Surrounding rock deformation control of gob-side coal-rock roadway in inclined coal seams (GCRICS) is a major problem in gob-side entry technology application practice. This paper describes a case study of the surrounding rock deformation characteristics and control technology of a typical GCRICS in Guizhou, China. As according to data obtained during a field investigation, the reasons for the deformation and failure of 151509 tailentry and the shortcomings of the original support scheme were analyzed. In combination with existing theory and field experience, the “anchor cable + U-shaped steel + shotcreting + grouting” (CUSG) support method was proposed. The plastic zone distribution, displacement, and stress evolution law of the roadway-surrounding rock under the four support modes were analyzed and compared by numerical simulation. The results show that the supporting effects of several support methods varied from good to poor; CUSG was the best, followed by anchor cable support, U-s... [more]

The development and adoption of digital twins (DT) for Quality-by-Design (QbD)-based processes with flexible operating points within a proven acceptable range (PAR) and automation through Advanced Process Control (APC) with Process Analytical Technology (PAT) instead of conventional process execution based on offline analytics and inflexible process set points is one of the great challenges in modern biotechnology. Virus-like particles (VLPs) are part of a line of innovative drug substances (DS). VLPs, especially those based on human immunodeficiency virus (HIV), HIV-1 Gag VLPs, have very high potential as a versatile vaccination platform, allowing for pseudotyping with heterologous envelope proteins, e.g., the S protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). As enveloped VLPs, optimal process control with minimal hold times is essential. This study demonstrates, for the first time, the use of a digital twin for the overall production process of HIV-1 Gag VLPs... [more]

An air curtain machine is used in the entrances and exits of public places where air conditioners are used. The high-speed centrifugal or axial fan blows out the air, creating an airflow barrier to prevent air convection inside and outside, reducing air conditioning losses, and maintaining the indoor air quality by preventing dust, insects, and harmful gases from entering the room. Observation of the airflow behavior was conducted using CFD simulation, to explore whether it has a blocking effect, and the air curtain principle was applied to the air purification equipment. It is mainly composed of several rows of arrayed hole air outlets to form a multi-composite air wall. The airflow on the two sides, or below, can be blocked by the composite air wall and integrated into the main airflow, so that the air walls will not affect each other, and form a barrier effect to prevent infection. This research includes the measurement of impedance characteristics for three layers of filters made o... [more]

For a blood pump, the blood flow channel and impeller parameters directly affect the performance of the pump and the resulting blood circulation. The flow channel in particular has a great impact on the hydraulic performance of the pump (e.g., flow and pressure), which directly determines the overall performance of the blood pump. Traditional bearing-supported blood pumps can cause mechanical damage to blood cells, leading to hemolysis and thrombosis. In this study, therefore, we designed a conical spiral axial blood pump with magnetic levitation. The blood pump was supported by electrodynamic bearings in the radial direction and electromagnetic bearings in the axial direction. The impeller and the front and rear hubs were integrated to minimize blood stagnation and reduce the formation of thrombosis. The hub had a conical spiral flow channel design, which not only reduced the size of the impeller but also increased blood flow and pressure while meeting the design requirements. Computa... [more]

The production profile logging technology of Oil-water two-phase flow is an important support technology for efficient development of horizontal oil wells. Moreover, the water holdup of Oil-water two-phase flow is one of the important dynamic measurement parameters for production profile logging technology. Flow patterns in horizontal oil wells are more complex than those in vertical oil wells, making water holdup measurements more difficult. In China, horizontal oil wells are characterized by low liquid production, high water cut and layered development; hence, the concentrating flow logging scheme is adopted to reduce the effects of flow patterns on measurement. In this paper, we proposed a new method of measuring water holdup of Oil-water two-phase flow for the production profile logging in horizontal oil wells. Firstly, the structure of water holdup sensors and the measuring principle of water holdup were introduced. Secondly, the dynamic test research was carried out on the horizo... [more]

On one hand, a blowout test can clean the bottom of the well, and on the other, it can learn the productivity of the well, which is important work before putting the well into production and also the main basis for production allocation of the well. The accurate prediction of the blowout test process provides a theoretical basis for the design of a reasonable blowout test system and the determination of well cleaning time. During deepwater blowout tests, gas and liquid flows are unsteady in pipes, and flow parameters change over time. At present, accurately predicting changes in fluid temperature, pressure, liquid holdup, and other parameters in a wellbore during an actual blowout process using the commonly used steady-state prediction methods is difficult, and determining whether a test scheme is reasonable is impossible. Therefore, based on the conservation of mass, momentum, and energy during the blowout test process, in this study, formation, wellbore, and nozzle flows were coupled... [more]

In this paper, three types of air guide vanes are designed: direct-type, L-type, and logarithmic spiral type, respectively. ANSYS-FLUENT 20.0 is used to numerically simulate the internal flow field of turbo air classifier by novel different structures. The numerical results show that the guide vane structures have a good effect on the flow field stability of the annular function zone in the classifying chamber. The distribution of tangential velocity and radial velocity verified the logarithmic spiral guide vane, and makes the airflow flow along the rotor cage circumferentially uniformly. In addition, the turbulent dissipation rate and energy loss decreases in the rotor cage region, which also shows that the guide vane is beneficial to improve classification performance. The tromp curve of the numerical simulation shows that the logarithmic spiral guide vane reduced the cutting size by 6.3% and 23.7% at two different process parameters, and is obviously better than other guide vane str... [more]

The pressure swing adsorption (PSA) process has been considered a promising method for gas separation and purification. However, experimental methods are time-consuming, and it is difficult to obtain the detailed changes in variables in the PSA process. This review focuses on the numerical research developed to realize the modelling, optimization and control of the cyclic PSA process. A complete one-dimensional mathematical model, including adsorption bed, auxiliary devices, boundary conditions and performance indicators, is summarized as a general modelling approach. Key simplified assumptions and special treatments for energy balance are discussed for model reliability. Numerical optimization models and control strategies are reviewed for the PSA process as well. Relevant attention is given to the combination of deep-learning technology with artificial-intelligence-based optimization algorithms and advanced control strategies. Challenges to further improvements in the adsorbent datab... [more]

Pollution of aquifers by liquid radioactive waste is especially hazardous due to high permeability of aquifer rocks. Pollution can take place as a result of deep injection disposal of liquid waste or due to its leakage from a surface reservoir. The ecological hazard depends on distribution of aquifer permeability, which can be highly heterogeneous. The only source of data for determination of such distribution is measurements in exploratory boreholes at the polluted site. A technique is proposed for determination of spatial distribution of aquifer transmissibility on the basis of hydrological measurements in a limited number of boreholes. The problem is reduced to a minimization problem which was solved numerically.

Quality-by-Design (QbD) is demanded by regulatory authorities in biopharmaceutical production. Within the QbD frame advanced process control (APC), facilitated through process analytical technology (PAT) and digital twins (DT), plays an increasingly important role as it can help to assure to stay within the predefined proven acceptable range (PAR).This ensures high product quality, minimizes failure and is an important step towards a real-time-release testing (RTRT) that could help to accelerate time-to-market of drug substances, which is becoming even more important in light of dynamical pandemic situations. The approach is exemplified on scFv manufacturing in Escherichia coli. Simulation results from digital twins are compared to experimental data and found to be accurate and precise. Harvest is achieved by tangential flow filtration followed by product release through high pressure homogenization and subsequent clarification by tangential flow filtration. Digital twins of the membra... [more]

Awareness of granulated soils’ internal instability is an important parameter when designing granulated filters, and the ability of a granulated soil’s internal stability can be verified using the soil PSD (Particle Size Distribution) curves’ secant slopes. The current work presents a new method to calculate the soil PSD curves’ secant slopes automatically, and a synthetic diagram is presented for the potential examination of the granulated soils’ internal stability. To verify the feasibility and accuracy of this synthetic diagram, 80 specimens of soil were investigated in this work and categorized into two groups: 50 sand−gravel soils and 30 (clay)−silt−sand−gravel soils. The obtained conclusions indicate that the internal stability and instability potentials of sand−gravel soils can be distinguished successfully with a synthetic chart and the Kenney and Lau criterion but cannot be assessed with the Kezdi and Sherard criteria. None of the criteria studied here can be used for the inte... [more]

Increase in downhole mining prompts the need to develop effective methods for maintenance of shafts. Currently, grouting behind the shaft wall is the main approach used for prevention of water seepage into the shaft. Several factors determine the grouting effect, and grouting often fails during field applications due to use of ineffective parameters. In the present study, numerical simulation was performed to evaluate slurry diffusion regularity under different grouting parameters based on the factors that affect shaft grouting. The simulation results showed that the overall diffusion radius of the slurry increased with increase in grouting time and stabilized toward the end of the simulation, under different grouting parameters. Porosity of the surrounding rock near the grouting hole gradually became denser with an increase in time, which is not conducive for diffusion of the slurry. The amount of water gushing at 146 m below the secondary shaft of Zhundong No. 2 mine decreased by 81%... [more]

This study used first-principle calculations and CALPHAD simulations to investigate the effects of adding Mo to NiAl laser-clad coatings in terms of metastable phase equilibria and Fe diffusion path with a focus on thermodynamic phase stability and element diffusion behavior. First-principle calculations were performed using 3 × 3 × 3 supercells to determine the formation energies of NiAl and Mo-rich phases within a Mo-doped NiAl cladding layer. The findings of this analysis are consistent with the d-orbital energy and bond order results obtained using DV-Xa molecular orbital calculations and phase diagrams obtained using Thermo-Calc simulations. The results also revealed that the substitution of Ni and Al atoms for Fe and Mo in the NiAl matrix decreased the stability of the B2 structure, thereby reducing phase formation energy. DICTRA simulations were also performed to characterize the diffusion behavior of Fe from the substrate to the surface of the coating. This analysis revealed th... [more]

The demand for precise separation of particles, cells, and other biological matter has significantly increased in recent years, leading to heightened scientific interest in this topic. More recently, due to advances in computational techniques and hardware, numerical simulations have been used to guide the design of separation devices. In this article, we establish the theoretical basis governing fluid flow and particle separation and then summarize the computational work performed in the field of particle and cell separation in the last five years with an emphasis on magnetic, dielectric, and acoustic methods. Nearly 70 articles are being reviewed and categorized depending on the type of material separated, fluid medium, software used, and experimental validation, with a brief description of some of the most notable results. Finally, further conclusions, future guidelines, and suggestions for potential improvement are highlighted.

In the classical Economic Order Quantity (EOQ) model, the common unrealistic assumptions are that all the purchased items are of perfect quality and the demand is constant. However, in a real-world environment, a portion of the purchased items might be damaged due to mishandling or an accident during the shipment process, and the demand rate may increase or decrease over time. Many companies are torn between repairing or replacing the imperfect items with new ones. The right decision on that options is crucial in order to guarantee that there is no shortage of stocks while at the same time not jeopardising the items’ quality and maximising the company’s profit. This paper investigates two EOQ models for imperfect quality items by assuming the demand rate varies with time. Under Policy 1, imperfect items are sent for repairs at an additional cost to the makeup margin; under Policy 2, imperfect items are replaced with equivalent quality items from a local supplier at a higher price. Two... [more]

Collisions between ships and offshore platforms frequently occur, with severe consequences. Predicting the collision depth under different conditions is very important to evaluate the severity of the consequences. Considering the time-consuming numerical simulation problem and the accuracy problems of existing approximation algorithms, this paper proposes a comprehensive approach to estimating penetration depths by obtaining two collision coefficients for specific collision structures based on the partial results of numerical simulations and simplified theoretical analysis. In this study, the collision process between a supply ship with a transverse framing stern and an offshore semi-platform was first numerically simulated based on the explicit dynamic method. The changes in ship velocity, impact force, and energy conversion before and after the collision processes were obtained through numerical simulations of the collisions with different speeds and angles. Then, by combining the ex... [more]

Due to the strong demand for organic light-emitting diode (OLED) display products and the highly competitive global market, OLED enterprises need to proactively make product innovations for presuming business competitive advantage, high sales, high profits, high customer consuming value, and the sustainability of the enterprise. A suitable multi-criteria decision-making (MCDM) model for OLED new product development (NPD) can help OLED enterprises’ R&D team to minimize risks and maximize the success rate of NPD. However, the literature reviews of the MCDM model for OLED NPD are very rare. This study aims to propose the approaches for establishing an integrated MCDM model for OLED NPD that apply three methodologies which include the literature review and expert panel, Interpretive structural modeling (ISM), and Fuzzy analytic network process (FANP). Meanwhile, after the implication of the proposed approaches in the case study of Taiwan OLED NPD, this study proposes an integrated MCDM mod... [more]