Fluid Velocity Research Articles

التصميم ألامثل للعملية الهيدروليكية لرأس الحفر

All drilling companies emphasize the importance of maintaining optimum drilling bit hydraulics in real-time drilling operations. The behavior of flow rate and pressure plays a crucial role in monitoring and optimizing drilling processes. By ensuring the hydraulic conditions are optimal, various drilling-related issues such as equipment failure, wellbore instability, and kicks can be minimized, resulting in significant time and cost savings. The paper's main objective is to illustrate the impact of mud pump flow rate optimization on the cutting Transport Fluid Velocity (TFV). This optimization directly influences the pressure loss inside the drill string and annular space, which, in turn, affects the selection of optimum nozzle sizes. The goal is to achieve efficient bottom hole cleaning and hole conditioning, ultimately leading to satisfactory rates of penetration (ROP). The study conducted a series of tests using different pump flow rates ranging from 100 to 500 gallons per minute (gpm) to drill two different sections. An 8 ½" bottom hole assembly (BHA) with a Tri-cone bit and a 6 1/8" BHA with a Polycrystalline Diamond bit were used. The WellPlane Software was employed for optimization. The results of the study indicate that for the 8 ½" section, a minimum pump rate of 488.3 gpm is necessary to avoid cutting accumulation and the formation of bed height. On the other hand, for the 6 1/8" section, a minimum pump rate of 193.2 gpm is required. The optimal parameters for achieving a bed height of zero in the 8 ½" section are a pump flow rate of 500 gpm and nozzle size of (316). For the 6 1/8" section, a pump flow rate of 250 gpm and nozzle size of (514) are recommended. In summary, the optimization of bit hydraulics is essential for mitigating drilling problems and reducing overall drilling costs. By maintaining proper flow rate and pressure conditions, along with appropriate nozzle sizes, efficient bottom hole cleaning can be achieved, leading to improved rates of penetration and overall drilling performance.

Thermal management of lithium-ion battery modules optimized based on the design of cold plate with convex pack structure

To address the issue of temperature increase in battery modules using liquid cooling plates, a convex pack structure within the flow channel is proposed to enhance flow efficiency. High temperatures can lead to battery performance deterioration, increased safety risks, and reduced service life. The optimal parameters for the convex structure (radius, transverse spacing, and longitudinal spacing) were determined through simulation analysis and orthogonal experiments. The effects of discharge rate, ambient temperature, coolant inlet temperature, and inlet speed on the heat dissipation of the battery module were also studied. The results show that the convex pack structure enhances heat transfer by increasing the contact area and fluid velocity while inducing eddy currents to achieve lateral mixing. The optimal parameters were found to be: radius (r) = 0.75 mm, horizontal spacing (x) = 3.50 mm, and vertical spacing (y) = 4.50 mm. At low discharge rates, the battery performs well, but high discharge rates negatively affect temperature uniformity. An increase in ambient temperature raises the temperature difference and maximum battery temperature. Lower coolant inlet temperatures reduce the maximum temperature but may result in uneven temperature distribution. Achieving a balanced coolant flow rate is essential to minimize temperature variations and control pressure buildup. This research introduces an innovative heat transfer structure, the convex pack, which significantly improves cooling efficiency. Further research on enhanced heat transfer structures is necessary to continue advancing cooling technologies for battery modules.

How to undertake respiratory auscultation with infants and children.

Respiratory auscultation involves listening to and interpreting sounds from within the chest. Undertaking respiratory auscultation effectively requires appropriate equipment, knowledge of physiology and pathophysiology and experience in listening to and interpreting breath sounds. Nurses undertaking this procedure must ensure they have the knowledge and skills to do so and work within the limits of their competence. This article provides a step-by-step guide that explains how to undertake respiratory auscultation with infants and children aged 0-16 years. • Respiratory auscultation is an essential procedure for informing differential diagnoses and assessing the trajectory of a child's illness and response to treatment. • In children with structurally normal, healthy lungs and a regular breathing pattern, the respiratory sound should be relatively quiet, with regular movement of air along the trachea and bronchioles, in and out of the lungs. • Any breath sounds heard in unexpected areas requires further investigation, while a complete absence of breath sounds must be treated as a clinical emergency and assistance from the medical team must be sought immediately. REFLECTIVE ACTIVITY: 'How to' articles can help to update your practice and ensure it remains evidence based. Apply this article to your practice. Reflect on and write a short account of: • How this article might improve your practice when undertaking respiratory auscultation with infants and children. • How you could use this information to educate nursing students or your colleagues on the procedure for undertaking respiratory auscultation with infants and children.

FORMULATION AND EVALUATION OF FLUTICASONE PROPIONATE-LOADED MICROEMULSION

This report focuses on the development of nanoemulsions, highlighting their potential as innovative drug delivery systems. The study, titled "Fluticasone Butyrate-Equipped Micelle Liposomal Delivery," aims to improve dissolution rates and bioactivity. The emulsifier structures showed a clear quantum fluid velocity, and in-vitro studies since 2005 revealed that certain formulations enhanced drug dissolution rates compared to others. This improved solubilization could extend bioactivity, as seen with atropine propionate. The study also examined the physicochemical properties, with results depending on the composition of surfactant, co-surfactant, water, and oil in the formulations. Process graphs indicated thicker emulsifier regions at the micellar margin, which led to improved formulations. Enhanced dissolution rates, particularly in oil-based drugs, were linked to the presence of nano-sized particles (54.30 nm) with a zeta potential of +/-10.61 mV. Stability tests confirmed that the solid dispersion remained stable for six months. Overall, this research supports the potential of nanoemulsions to improve drug delivery and efficacy.

Study on the Flow and Heat Transfer Performance of Microchannel Heat Exchangers With Different Elliptical Concave Cavities

AbstractEllipticity has a significant impact on the flow and heat transfer performance of microchannel heat exchangers (MHEs) with elliptical concave cavities. In this study, five types of MHEs with different elliptical concave cavities (ellipticities of 0.4, 0.6, 0.8, 1.0, and 1.2) were designed. The influence of ellipticity on the flow and heat transfer performance of MHEs was numerically investigated using ANSYS Fluent 21.0 R1. Moreover, MHEs with corresponding elliptical concave cavities structures were processed and manufactured, and then an experimental platform was designed and built for experimental verification. The results showed that the fluid velocity distribution in MHEs with elliptical concave cavities was symmetrical, and the formation of secondary flow in the elliptical concave cavities led to the continuous destruction and reconstruction of the flow and thermal boundary layer in the microchannel, which is conducive to mass and heat transfer in the MHEs with elliptical concave cavities. The inlet and outlet pressure drop of MHEs with elliptical concave cavities increased as the inlet flow rate increased. At the same inlet flow rate, the inlet and outlet pressure drop of the MHE with elliptical concave cavities first increased and then decreased with increasing ellipticity. At an ellipticity of 1.0, the inlet and outlet of MHE exhibited the lowest pressure drop indicating that the MHE with an ellipticity of 1.0 featured the highest pressure drop performance. The cold‐water outlet temperature of the MHEs with elliptical concave cavities first decreased and then increased as the inlet flow rate increased. At the same inlet flow rate, the cold‐water outlet temperature of the MHEs with elliptical concave cavities first increased and then decreased with increasing ellipticity, while the hot‐water outlet temperature of the MHEs first decreased and then increased with increasing flow rate. This indicated that the MHE with an ellipticity of 1.0 exhibited excellent heat transfer performance.

Numerical simulation of heat transport mechanism in chemically influenced ternary hybrid nanofluid flow over a wedge geometry

Ternary hybrid nanofluid flow over a wedge surface facilitates optimization, promotes industrial processes such as heat transfer, temperature regulation, material compatibility, energy efficiency and is very useful in equipment design. Due to this attention the current study focalizes the heat diffusion and mass transportation in ternary hybrid (TiO2-AL2O3-SiO2) nanofluid flow over a stretching/shrinking wedge geometry. Additionally, Ternary hybrid flow is examined under the impact of activation energy together with chemical reactions. The nanofluid flow process is structured using Modified Boungiorno Model together with framed set of partial differential equation (PDEs). The resulting systems is altered into non dimensional form of ordinary differential equation (ODEs) using transform functions and linearization is obtained through shooting technique. MATLAB bvp4c solver scheme is utilized for numerical findings of the problem. Influence of key parameters are analyzed on velocity, temperature, and concentration field. Fluid concentration intensifies via augmentation in activation rate whereas wedge stretching due to larger values of wedge angle, lessens velocity of fluid. Heat transportation escalate with higher values of fluid index, whereas negative trend is seen in case of higher value of Brownian parameter.

The impact of suction/injection with radiation effect on natural convection flow over a vertical channel in the existence of point/line heat source configuration

The present study manifests the significance of a heat source concentrated at a point or along a line on the natural convection flow featuring suction/injection and radiation effect within a vertical channel. The consistent heat source is modeled with the Heaviside step function and converted to a point/line heat source. The governing equations modeling the flow are resolved by the Laplace transform technique. Shear stress, Nusselt coefficient, and mass flow rate, along with respective values, are examined through the analysis presented in tables whilst the physical components like suction/injection ( K ), Prandtl number (Pr), heat source (S), and radiation (N) are explored graphically on the velocity and the temperature field. Results illustrate that the temperature and the fluid velocity intensify with the escalation of point/heat source attributes. However, as the parameters Pr, K and N increase, the velocity distribution decelerates. In addition, the heat transfer rate gradually diminishes with an elevation in radiation, and reducing the line heat source to that of point heat source parameters corresponds to a decrease in the rate of heat transfer. Also, in the absence of radiation, the current finding aligns seamlessly with the established research in the literature.

Particle trajectories in the KP-II equation

In the current work, we consider particle trajectories beneath traveling soliton solutions described by the Kadomtsev–Petiviashvili-II (KP-II) equation, which is a model for small-amplitude water waves in shallow water. The KP-II equation has a large number of exact solutions describing crossing line solitons. Here, we describe the particle drift induced by the single line soliton and various two- and three-soliton solutions on a two-dimensional horizontal domain.First, the derivation of the KP-II equation is used to exhibit expressions for the three components of the fluid velocity vector induced by a surface wave profile given by the KP-II equation. These velocity components can be used to specify a coupled system of ordinary differential equations (ODEs) which describe the motion of a fluid particle. Given an initial position inside the fluid for a specific particle, as well as continuously providing time-dependent values for the surface deflection, the ODE system can be solved numerically to find the particle path induced by the passage of a wave. A special numerical integration grid tracking the particle is used to handle integral terms occurring in the fluid velocity expressions.

Couette flow of viscoelastic dusty fluid through a porous oscillating plate in a rotating frame along with heat transfer

AbstractUsually, suction/blowing is used to control the channel's fluid flow, which is why this worth‐noting effect is considered. The fluid velocity is considered along the x‐axis due to the oscillations of the right plate. The thermal effect on the flow due to the heated right plate is also considered. The fluid and dust particles have complex velocities due to the rotation, which are the sum of primary and secondary velocities. To convert the aforementioned physical phenomenon into mathematical form, partial differential equations are used for modeling the subject flow regime. Appropriate nondimensional variables are employed to nondimensionalize the system of governing equations. With the assistance of assumed periodic solutions, the system of partial differential equations is reduced to a system of ordinary differential equations which is then solved by the perturb solution utilizing Poincare–Lighthill perturbation techniques. The engineering interest quantities, the Nusselt number, and skin friction are also determined. The impact of various parameters on skin friction, viscoelastic fluid, and dust particle velocity profiles is also investigated. It is worth mentioning that suction controls the boundary layer to grow unexpectedly, even in the resonance case. The obtained solution is also valid in the case of injection. The radiation parameter, Grashof number, and second‐grade parameter cause a decrease in skin friction as their values increase. On the other hand, the suction, rotation, magnetic, dusty fluid, and Reynolds numbers cause a rise in skin friction.

Melting performance of PCM with MoS2 and Fe3O4 nanoparticles using leaf-based fins with different orientations in a shell and tube-based TES system

Phase change materials (PCMs) are frequently utilized in the thermal sector, especially for thermal energy storage (TES) applications. The purpose of this study was to analyze the thermal efficiency and melting characteristics of a leaf-vein-shaped fin in a triplex tube heat exchanger. The analysis focused on the use of pure molten salt PCM and a combination of molten salt PCM with MoS2 and Fe3O4 nanoparticles. The study utilized ANSYS Fluent software to conduct numerical simulations and analyze seven distinct fin arrangements. The simulations were employed to visualize and examine the liquid fraction, temperature, and fluid velocity. The findings indicated that the leaf-vein fin shape greatly improved the dispersion of liquid fraction, average temperature, and velocity in comparison to alternative fin designs. The addition of MoS2 and Fe3O4 nanoparticles significantly enhanced the melting and thermal characteristics of the PCM as a result of heightened thermal conductivity. This showcases the capability of the leaf-vein fin design and PCM nanocomposites to enhance the efficiency of thermal energy storage in triplex tube systems. About 2500 s PCM melt about 36% for case A, but melting rate enhance up-to 55% using nano particles. Melting rate enhance 91% in 1000 s in case of G using 8 fins as compare to case A having no fins.

An integrated micromachined flexible ultrasonic-inductive sensor for pipe contaminant multiparameter detection

Pipe contaminant detection holds considerable importance within various industries, such as the aviation, maritime, medicine, and other pertinent fields. This capability is beneficial for forecasting equipment potential failures, ascertaining operational situations, timely maintenance, and lifespan prediction. However, the majority of existing methods operate offline, and the detectable parameters online are relatively singular. This constraint hampers real-time on-site detection and comprehensive assessments of equipment status. To address these challenges, this paper proposes a sensing method that integrates an ultrasonic unit and an electromagnetic inductive unit for the real-time detection of diverse contaminants and flow rates within a pipeline. The ultrasonic unit comprises a flexible transducer patch fabricated through micromachining technology, which can not only make installation easier but also focus the sound field. Moreover, the sensing unit incorporates three symmetrical solenoid coils. Through a comprehensive analysis of ultrasonic and induction signals, the proposed method can be used to effectively discriminate magnetic metal particles (e.g., iron), nonmagnetic metal particles (e.g., copper), nonmetallic particles (e.g., ceramics), and bubbles. This inclusive categorization encompasses nearly all types of contaminants that may be present in a pipeline. Furthermore, the fluid velocity can be determined through the ultrasonic Doppler frequency shift. The efficacy of the proposed detection principle has been validated by mathematical models and finite element simulations. Various contaminants with diverse velocities were systematically tested within a 14 mm diameter pipe. The experimental results demonstrate that the proposed sensor can effectively detect contaminants within the 0.5−3 mm range, accurately distinguish contaminant types, and measure flow velocity.

Three-dimensional simulation on phase change heat transfer of moving spherical particle

Investigating the motion process of paraffin particle under a mesoscopic scale is very helpful to master the heat transfer mechanism of the mushy zone in solid–liquid phase change. Prior researches predominantly focused on either particle motion or phase change, without accounting for their coupling. In this study, the three-dimensional finite element method is used to solve the motion and heat transfer of the particle, taking into account the coupling of motion and phase change. The moving grid is employed to trace the interface of moving particles and liquid using the Arbitrary Lagrangian-Euler method, which is able to calculate flow and heat transfer in fluid region and allow grid deformation in solid region. The results indicate that uneven fluid velocity around the particles results in non-uniform temperature gradients on particle’s surface. In areas with larger temperature gradient, it melts more quickly and its deformation is obvious. The maximum is located at particle orientation angle 30°. Changing the size and direction of fluid velocity will reinforce or inhibit the movement of particle. The changing time of motion direction when fluid velocity is −0.03 m/s shorten 2.7 times than when fluid velocity is −0.01 m/s. The initial temperature of the surrounding fluid has a positive relationship with the particle melting rate. The channel width affects significantly the motion and melting of particle. The initial position of particle has an important effect on it’s falling movement, and the closer is close to the wall of channel, the greater the displacement of left and right movement.

Polarized image of a synchrotron emitting ring around a static hairy black hole in Horndeski theory

In this paper, we investigate the polarization images of a synchrotron-emitting fluid ring surrounding a static hairy black hole within the framework of Horndeski’s theory. Our findings indicate that the characteristics of these polarization images are predominantly influenced by the hairy parameter, alongside the magnetic field near the black hole, the fluid’s velocity, and the observer’s inclination angle. Specifically, the hairy parameter primarily affects the polarized intensity and the apparent radius of the ring in the images. Conversely, the impacts of the magnetic field, fluid velocity, and inclination angle on the polarization images are found to be independent of the hairy parameter and closely resemble those observed in the context of Schwarzschild black holes. Additionally, the polarization direction is significantly influenced by the magnetic field orientation, while the inclination angle crucially determines the apparent flatness of the images. Variations in the fluid velocity direction also markedly affect the trend in polarized intensity. Furthermore, we explore how these parameters influence the Stokes Q-U\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Q-U$$\\end{document} loops, revealing distinct behaviors in response to changes in the aforementioned variables. This comprehensive analysis enhances our understanding of the intricate dynamics and observational signatures of black holes within alternative gravitational theories.

Flow control by a hybrid use of machine learning and control theory

PurposeFlow control has a great potential to contribute to a sustainable society through mitigation of environmental burden. However, the high dimensional and nonlinear nature of fluid flows poses challenges in designing efficient control laws using the control theory. This paper aims to propose a hybrid method (i.e. machine learning and control theory) for feedback control of fluid flows, by which the flow is mapped to the latent space in such a way that the linear control theory can be applied therein.Design/methodology/approachThe authors propose a partially nonlinear linear system extraction autoencoder (pn-LEAE), which consists of convolutional neural networks-based autoencoder (CNN-AE) and a custom layer to extract low-dimensional latent dynamics from fluid velocity field data. This pn-LEAE is designed to extract a linear dynamical system so that the modern control theory can easily be applied, while a nonlinear compression is done with the autoencoder (AE) part so that the latent dynamics conform to that linear system. The key technique is to train this pn-LEAE with the ground truths at two consecutive time instants, whereby the AE part retains its capability as the AE, and the weights in the linear dynamical system are trained simultaneously.FindingsThe authors demonstrate the effectiveness of the linear system extracted by the pn-LEAE, as well as the designed control law’s effectiveness for a flow around a circular cylinder at the Reynolds number of ReD = 100. When the control law derived in the latent space was applied to the direct numerical simulation, the lift fluctuations were suppressed over 50%.Originality/valueTo the best of the authors’ knowledge, this is the first attempt using CNN-AE for linearization of fluid flows involving transient development to design a feedback control law.

Dispersion of particles in a sessile droplet evaporating on a heated substrate

A coupled volume-of-fluid (VOF) and discrete element model (DEM) is developed and used to study the dispersion of particles in an evaporating pinned sessile droplet on a heated substrate. Fully resolved simulations of evaporating droplets are performed to study the effects of substrate temperature and the Marangoni stresses to study the fluid flow and temperature distribution within the droplet. The fluid flow inside the evaporating droplets is used to predict the behavior of particles, studying the effect of relative particle density and the aforementioned effects on the particle dispersion within the droplet. This study shows that the presence of Marangoni stresses significantly affects the flow and temperature distribution inside the droplet, which, in turn, influences the dispersion of particles in the droplet. The fluid velocity induced by the Marangoni stresses is nearly two orders of magnitude larger than the velocity generated by capillary flow as a result of evaporation, promoting a strong convective mixing within the droplet, while working to equilibrate the temperature distribution at the interface. In the absence of Marangoni stresses, the dispersion of particles is governed by the competing effects of adsorption by the downward-moving interface as a result of evaporation, and particle sedimentation under the influence of gravity. However, both these effects become less dominant in the presence of a flow induced by the Marangoni stresses, causing the particles to initially move toward the apex of the droplet along the interface and, subsequently, toward a stagnation point on the interface.

Unified framework for laser-induced transient bubble dynamics within microchannels

Oscillatory flow in confined spaces is central to understanding physiological flows and rational design of synthetic periodic-actuation based micromachines. Using theory and experiments on oscillating flows generated through a laser-induced cavitation bubble, we associate the dynamic bubble size (fluid velocity) and bubble lifetime to the laser energy supplied—a control parameter in experiments. Employing different channel cross-section shapes, sizes and lengths, we demonstrate the characteristic scales for velocity, time and energy to depend solely on the channel geometry. Contrary to the generally assumed absence of instability in low Reynolds number flows (<1000\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$<1000$$\\end{document}), we report a momentary flow distortion that originates due to the boundary layer separation near channel walls during flow deceleration. The emergence of distorted laminar states is characterized using two stages. First the conditions for the onset of instabilities is analyzed using the Reynolds number and Womersley number for oscillating flows. Second the growth and the ability of an instability to prevail is analyzed using the convective time scale of the flow. Our findings inform rational design of microsystems leveraging pulsatile flows via cavitation-powered microactuation.

Building Performance Strategy to Achieve Thermal Comfort on Post-Disaster Design

Purpose: This study is a development of previous studies that focused on testing building performance from the aspect of building comfort. A house is a place to live that is used daily that must meet the needs of the occupants' thermal comfort which is greatly influenced by environmental and building conditions, such as natural lighting, air flow, and thermal performance as well as the conditions of the building's orientation layout and space openings. To determine the thermal performance of a building, it is necessary to conduct several analyses of several parameters of air temperature, air circulation and thermal conditions that occur in buildings in several conditions of building layout or orientation and openings made. Theoretical reference: Adaptive buildings are buildings that have adaptation to external environmental conditions, occupant needs and building operational conditions with the aim of increasing energy efficiency, comfort and sustainability. These adaptive buildings are able to provide a more comfortable environment, flexible and efficient space by maximizing natural ventilation and using building materials that function as insulation against temperature and solar radiation. Method: To determine the thermal comfort conditions of the building, it is necessary to conduct several tests on several parameters, such as natural lighting, air flow, and thermal performance using several analyzes such as solar analysis, air movement analysis and thermal analysis of the planned building prototype with several alternative building orientations. To test the thermal performance of the building, solar analysis and thermal analysis are carried out using Revit-based computational fluid dynamics (CFD). Results and Conclusions: The results of the study showed that the influence of building orientation and opening placement patterns will produce several different thermal performances. And the optimal results obtained from this adaptive strategy were that the optimal heat generated caused heat generation in the envelope of 0.76 kW/m2, meaning that by considering the heat transfer value of the building envelope not exceeding 35 W/m2 (SNI 6389:2020), a wall envelope made of 10 cm thick calciboard with air holes was used to withstand the rate of heat flow into the room. Research implications: As part of the adaptive building context that supports the field of knowledge and practice in the fields of architecture, engineering and the environment, it has positive implications related to the flexibility of spatial arrangement to adjust to the needs of occupants' space, the use of more efficient and environmentally friendly building technology and materials according to the needs of adaptive buildings, and the adjustment of natural ventilation strategies according to local climate potential. Originality/value: The components that distinguish this research from previous research can be seen from the various approaches and innovations carried out by the author, namely: Adaptive Design Method: developing the functionality of spatial arrangements in post-disaster residential buildings that apply the principles of spatial efficiency and arrangement to improve more dynamic relationships between spaces and their relationships with the surrounding environment. Use of New and Data-based Technology: applying new technology in ways to monitor and control the quality of space with the surrounding environment that affects it in real-time. Using technology applications for data analysis, modeling and predicting the performance of post-disaster residential buildings according to environmental and building parameters that affect them, and using big data analysis to understand the thermal behavior of buildings to optimize building design and operations.

Numerical Simulation and Flow Field Analysis of Porous Water Jet Nozzle Based on Fluent

The water jet nozzle is a penetrating drilling tool, which sends the pumped water to the nozzle through a high-pressure hose. It can work in a variety of working environments. When it dredges the blockage in the pipeline, its structural parameters will affect the jet flow field in the pipeline. Taking the self-propelled water jet nozzle as the research object, SolidWorks was used to establish the nozzle model with different parameter structures. Based on Fluent, the k-ε turbulence model was used to simulate the jet of nozzles with different nozzle sizes and arrangements in the pipeline. The distribution of the jet flow field and the change in velocity and displacement of nozzles with different parameters in the pipeline were compared, and then computational fluid dynamics (CFD) were used to process the simulation data for further research. The results show that when the inclination angle of the rear nozzle is 35°, the attenuation of the front jet velocity and the fluctuation of the wall fluid velocity are the smallest. When the nozzle aperture is increased from 2 mm to 3.5 mm, the vortex area inside the pipe is reduced, and the velocity attenuation of the front jet is also reduced, with the velocity attenuation rate decreasing by about 10%. This study provides a reference for the design and parameter optimization of self-propelled water jet nozzles.

Micro-macro SERS strategy for highly sensitive paper cartridge with trace-level molecular detection

Surface-enhanced Raman Scattering (SERS) has become a powerful spectroscopic technology for highly sensitive detection. However, SERS is still limited in the lab because it either requires complicated preparation or is limited to specific compounds, causing poor applicability for practical applications. Herein, a micro-macro SERS strategy, synergizing polymer-assisted printed process with paper-tip enrichment process, is proposed to fabricate highly sensitive paper cartridges for sensitive practical applications. The polymer-assisted printed process finely aggregates nanoparticles with a discrete degree of 1.77, and SERS results are matched with theoretical enhancement, indicating small cluster-dominated hotspots at the micro-scale and thus 41-fold SERS increase compared to other aggregation methods. The paper-tip enrichment process moves molecules in a fluid into small tips filled with plasmonic clusters, and molecular localization at hotspots is achieved by the simulation and optimization of fluidic velocity at the macro-scale, generating a 39.5-fold SERS sensibility increase in comparison with other flow methods. A highly sensitive paper cartridge contains a paper-tip and a 3D-printed cartridge, which is simple, easy-to-operate, and costs around 2 US dollars. With a detection limit of 10 −12 M for probe molecules, the application of real samples and multiple analytes achieves single-molecule level sensitivity and reliable repeatability with a 30-min standardized procedure. The micro-macro SERS strategy demonstrates its potential in practical applications that require point-of-care detection.

Simulation of Magnetic Separation of Metal Ions in Aqueous Electrolytes

The magnetic separation of metal ions provides an alternative solution to traditional separation techniques such as pyrometallurgy, hydrometallurgy, biometallurgy or electrodialysis. Compared to traditional techniques that either use large amounts of chemicals (usually inorganic acids combined with reducing agent), produce large amounts of sludge as solid waste, consume a large amount of energy, or are difficult to separate ions of different charges [1], the magnetic separation of the metal ions can separate ions based on their magnetic susceptibility. This method is environmentally friendly [2] and consumes a small amount of energy (particularly when the system is designed using permanent magnets instead of electromagnets). The goal of this presentation is twofold. First, we derive the set of transport equations that need to be used to simulate the magnetic separation of metal ions in aqueous solutions. Then, we use these transport equations to simulate the magnetic separation process in various magnetic systems and predict the efficiency of magnetic separation of different systems.The mathematical model developed here is based on coupling the three-dimensional Navier-Stokes equations for flow transport with the drift (migration)-diffusion equations of ion transport [3] in the presence of magnetic field gradients. Both the drift-diffusion model and the Navier-Stokes equations include the magnetic force term as an additional driving force. By solving the entire system of equations self-consistently we analyze the effect of the diffusivity, concentration gradients, magnetic field gradients and fluid velocity over the capturing properties of the system. A detailed presentation of the mathematical model, underlying assumptions of the model, limiting cases, numerical implementation in three-dimensional structures, and simulations results will be presented at the meeting. In addition, we will present predictions for the magnetic separation of Li, Fe, Ni, Mn, and Co from the solution phase. Fortunately, these ions have significantly different magnetic susceptibility, which vary over more than 3 orders of magnitude, and which allows for the efficient extraction and separation of the elements from the solution and from each other.