Electromagnetic field (EMF) treatment is a promising nonchemical strategy for scale control in reverse osmosis (RO) desalination; however, the mechanisms by which it influences polymorph selection and competitive precipitation in multi-ionic waters remain poorly understood. Here, we present the first detailed temporal analysis of scale formation, elucidating how EMF alters CaCO3 and gypsum scaling in multi-ionic, Mg-bearing brackish groundwater (Mg/Ca = 0.67). Without EMF, aragonite and Mg-calcite co-precipitated, consistent with Mg & sup2;(+)-mediated inhibition of calcite growth. EMF accelerated bulk crystallization, amplified Mg & sup2;(+) suppression of calcite, and drove an almost complete shift toward aragonite precipitation while maintaining elevated Mg/Ca ratios. EMF also mitigated gypsum scaling by promoting early, uniform CaCO3 precipitation, reducing free Ca & sup2;(+) availability, and delaying gypsum nucleation during initial concentration stages. At high gypsum supersaturation, precipitation occurred under both EMF and control conditions; however, EMF produced more porous and loosely adherent gypsum deposits. This dual effect-favoring aragonite formation and delaying or modifying gypsum deposition-resulted in more uniform, easily removable scaling layers. Although short-term flux improvements were modest, these mechanistic shifts enhance long-term membrane performance and cleanability, particularly when combined with hydraulic flushing.

The mitigation of silica, calcium carbonate, and calcium sulfate scaling remains a major challenge for developing brackish water desalination. This study investigated the impact of electromagnetic fields (EMF) and permanent magnetic fields (PMF) in combination with antiscalant on membrane scaling control in brackish groundwater reverse osmosis (RO). The mechanisms of the (electro)magnetic field on membrane scaling were elucidated based on thermodynamic, kinetic, and transport comparisons of six treatment strategies. Saturation index analysis demonstrated that EMF reduced near-surface supersaturation for carbonate and sulfate minerals, whereas PMF temporally altered gypsum supersaturation. Kinetic measurements showed that both EMF and PMF selectively delayed sulfate-scale formation, extending gypsum induction time from 267 min to 531 min under EMF and 559 min under PMF. Transport analysis revealed EMF consistently limited concentration polarization (CP) compared with the untreated control, indicating improved mass transfer and reduced CP-layer development. These mechanistic effects resulted in improved membrane performance with EMF, including flux stability increased by ~25%, enhanced scaling reversibility (>94% recovery), and reduced CaCO₃/CaSO₄ deposition. The combination of EMF and an antiscalant provided the strongest suppression of mineral scaling; in contrast, PMF and PMF+antiscalant exhibited rapid flux decline driven by a mixed Ca–Si scaling mechanism, where dense CaCO₃/CaSO₄ cake layers enabled accelerated silica-gel accumulation under intensified CP as membrane scaling progressed. Overall, this study showed EMF provided fundamentally different and more effective scaling-control mechanisms over PMF during brackish water desalination, influencing both thermodynamic driving forces and surface-scale evolution.

Thin-film temperature gauges with nickel and silver sensing elements on a Macor ceramic substrate are evaluated for unsteady heat flux measurements in impulse facilities such as shock tunnels. Unsteady heat transfer simulations with known input heat flux provide resistance and temperature data. The heat flux is then recovered from inverse theory and compared with the known input heat flux. For the nickel-based sensor, the effect of the film thickness and film overlap with the insulator are investigated. Simulations with box and square function heat input demonstrate the dependence of the sensor frequency response on the film thickness. For the silver thin-film gauge, the effect of partial direct heat transfer into the surrounding insulator is investigated. The suitability of the silver thin film for time-resolved heat flux measurements in a turbulent high-speed boundary layer is evaluated. The unsteady wall heat flux is obtained from a large-eddy simulation of a high-enthalpy Mach 5 turbulent boundary layer in thermochemical nonequilibrium. Inverse analysis of the temperature data from the thin-film simulation provides the wall heat flux, which is in good agreement with the heat flux obtained directly from the large-eddy simulation, thus demonstrating that the thin-film gauge is well suited for impulse facility experiments.

This study investigates the impact of arterial stiffness on wall shear stress (WSS) reversal, a critical factor in vascular health and disease. The cardiovascular system's endothelial cells respond to mechanical stimuli, such as WSS, which influences vascular remodeling and the pathogenesis of cardiovascular diseases. Our hypothesis posits that increased arterial stiffness exacerbates WSS reversal, potentially affecting endothelial cell behavior. To test this, we conducted in-vitro experiments using transparent elastic tubings with varying stiffness to simulate arteries. A gear pump generated pulsatile flow, and 2D particle image velocimetry (PIV) was employed to measure velocity fields and calculate WSS. Our findings confirm that stiffer arteries lead to greater WSS reversal, highlighting the mechanobiological pathways linking arterial stiffness to vascular disease. The study also demonstrates that softer arteries dampen flow pulsatility, reducing the magnitude and duration of negative WSS. These results have significant implications for understanding the mechanistic pathways of vascular diseases and developing therapeutic strategies to mitigate the adverse effects of arterial stiffness. Future research should delve into the molecular mechanisms underlying endothelial responses to WSS reversal and explore potential interventions to preserve vascular health in the context of arterial stiffness. This work contributes to the growing body of evidence emphasizing the importance of mechanical forces in vascular biology and offers insights into the relationship between arterial stiffness and endothelial function.

Slug calorimeters are rugged and proven sensors for hypersonic flight and ground tests. Data reduction through inverse theory is employed to obtain the heat flux from the temperature time history. The unknown heat loss into the surrounding structure introduces inaccuracies. Other than through extensive calibration, the inaccuracies can be addressed by improved and new sensor designs and associated theory. In this paper, a novel design is proposed that addresses the unknown heat loss problem at the back face by adding a stainless steel part with a second thermocouple. This multilayered slug calorimeter design is being tested in a purpose-built laser heat flux facility. Measurements provide validation data for heat transfer simulations that are being employed for design parameter studies. The simulation data are used for the testing of novel inverse theory. The present results demonstrate that the proposed bimetal slug calorimeter, in combination with new inverse theory, can provide accurate heat flux measurements. To evaluate sensor performance in a representative environment, the Mach 18 airflow over a hemisphere was simulated, and the wall heat flux served as input for sensor heat transfer simulations. The analysis revealed a 20% variation in the heat flux prediction depending on the wall catalycity.

Reinforcement learning (RL)-based closed-loop flow control shows great potential for managing nonlinear and complex aerodynamic flows. In this study, we investigate RL-based flow control to enhance the lift-to-drag ratio of an NLF(1)-0115 airfoil at a chord-based Reynolds number of Re_c = 20,000 and an angle of attack α = 5^∘ . Key control parameters, including the reward function, agent action time, observed state, and actuator placement, are systematically examined. Our results reveal that physics-informed tuning significantly improves control performance. An optimal agent action time of τ = 0.07 , corresponding to approximately 11 34.1% to 35.5% , demonstrating the practical feasibility of using surface measurements. Forcing placement based on stability analysis significantly enhances control effectiveness. To improve data efficiency, the optimized 2D RL controller is transferred to a 3D CFD environment through prescribed spanwise wavenumber superposition. This lower-cost 3D controller effectively suppresses flow separation and significantly enhances aerodynamic performance. The results present a promising and practical alternative to direct 3D RL training for airfoil flow control.

A small supersonic indraft tunnel was designed to grow experimental capabilities at the New Mexico State University Mechanical and Aerospace Engineering Department. Indraft tunnels provide constant stagnation conditions and they are safe and inexpensive to operate. They are also well suited for dry climates such as New Mexico. Square nozzle contours for test section Mach numbers of 2.3, 3, 4, and 5 are found with a method of characteristics computer program with boundary layer correction. A fifth-order polynomial is utilized too for shaping the subsonic part of the nozzle. The Mach 2.3 nozzle is compared to the nozzle of a similar indraft tunnel at the University of Arizona. Two- and three-dimensional simulations provide information about the boundary layer displacement effect and the flow uniformity in the test section. Assuming isentropic flow, the run time of the tunnel is analyzed based on tank size. Finally, detailed computer-aided design drawings of the entire indraft tunnel are presented.

Electromagnetic field (EMF) is a cost-effective, simple, and energy-efficient method for scale control in reverse osmosis (RO) systems. However, its effects on gypsum and silica scaling, as well as the underlying mechanisms, remain poorly understood. This study systematically investigates the effects of EMF treatment on gypsum and silica scaling in RO systems, utilizing synthetic brackish water and natural RO concentrate (ROC) from a desalination facility. For gypsum, EMF changes the crystal morphology, resulting in the formation of a porous, less compact scaling layer. It is more readily removed through hydraulic flushing (HF), enhancing scaling reversibility and water recovery. In the case of silica scaling, EMF promotes homogeneous polymerization in the bulk solution, producing larger silica particles that inhibit the formation of a dense, cross-linked gel layer on the membrane surface, mitigating flux decline. This study thus demonstrates EMF's effectiveness in controlling gypsum scaling in undersaturated feedwaters when combined with HF and in mitigating silica scaling under both HF and non-HF conditions for supersaturated feedwaters. These findings underscore EMF's versatility as a nonchemical approach for scale control in RO desalination and show its substantial potential to enhance membrane performance and operational efficiency in real-world water treatment applications.

Dielectric Barrier Discharge plasma actuators have emerged as a highly practical Active Flow Control solution due to their low weight and cost, fast response time, and ease of installation. Active control with pulsed Dielectric Barrier Discharge plasma actuator of laminar separation for a wing section with NLF(1)-0115 airfoil at pre-stall angle-of-attack was investigated for chord-based Reynolds numbers in the range 20,000 to 100,000. For the wind tunnel experiments, a fiberglass wing model equipped with surface microphones and pressure taps was designed and built. Phase-locked Particle Image Velocimetry and unsteady pressure measurements from the surface microphones capture the dynamics of the shear-layer roll-up and the response to periodic forcing. With time-periodic actuation, the vortex shedding is organized and the flow separation is dramatically reduced for the lower Reynolds numbers. As a result, the lift is increased and the pressure drag is decreased. Time histories and frequency spectra of the microphone data reveal the growth of instability waves and the breakdown to turbulence. These findings provide a baseline understanding for future closed-loop Active Flow Control experiments.

This study presents the development and experimental validation of a novel bi-metallic slug calorimeter composed of explosively bonded copper and stainless steel layers. The sensor was tested under controlled radiative heat loads using a 1.5 kW continuous-wave laser. The heat flux was reconstructed from temperature data acquired with two thermocouples embedded in both layers of the sensor using a finite difference algorithm by assuming one-dimensional heat transfer. Two insulation materials, Macor and Microsil, were employed to evaluate their effect on suppressing heat loss in the radial direction. The results showed that Microsil, due to its low thermal conductivity, significantly reduced conductive losses in the radial direction and improved reconstruction fidelity. Additional tests using a back-side water cooling demonstrated an improved aptitude for tolerating higher heat fluxes and thus allowed for longer test durations without overheating. The reconstructed heat flux showed close agreement with the applied input, with errors lower than 5% in all cases, validating the effectiveness of both the bi-metallic design and the reconstruction method for heat flux measurement in high-enthalpy environments.

A prototype thin-film temperature gauge is presented for unsteady heat flux measurements in impulse facilities such as shock tunnels. The sensor consists of a thin silver film on a Macor ceramic substrate insulator. The design provides very short response times while minimizing the unknown heat loss towards the back boundary. Unsteady heat diffusion simulations of the thin-film temperature gauge were performed without and with external Macor housing. Simulations with box function heat input demonstrate the dependence of the sensor frequency response on the film thickness. When the sensor is placed in the Macor housing, lateral heat loss occurs, which can potentially degrade the measurement accuracy. The unsteady wall heat flux from a large-eddy simulation of a high-enthalpy Mach 5 turbulent boundary layer in chemical non-equilibrium provided the input data for an unsteady heat diffusion simulation of the thin-film gauge. Inverse analysis of the temperature data from the thin-film simulation provided the wall heat flux, which is in good agreement with the heat flux obtained directly from the large-eddy simulation, thus demonstrating that the thin-film gauge is well suited for impulse facility experiments.

Mineral scaling remains a persistent challenge in water treatment systems. Electromagnetic field (EMF) treatment provides a modular and chemical-free alternative to traditional antiscalants, with minimal environmental impact. EMF systems reduce common scales (e.g., CaCO₃, gypsum, silica), but performance is application-dependent, such as ~15–79 % fouling reduction in bench heat-exchanger/membrane-distillation tests and ~40–45 % lower scaling propensity in reverse osmosis pilot/field studies. This variability limits large-scale applications. This review synthesizes recent theoretical and experimental advances in EMF-based scale control. EMFs influence both homogeneous nucleation and heterogeneous crystal growth, reducing scale adhesion. The relative contribution of these mechanisms depends on water chemistry and system configuration, leading to varying levels of treatment efficiency. This variability also presents an opportunity: by modulating the balance between homogeneous and heterogeneous effects, EMF systems can be tailored to specific treatment needs, thereby broadening their applicability. The effectiveness of EMF treatment can be further enhanced through optimization of operational parameters such as field intensity, frequency, waveform, and flow velocity. These factors are examined through simulation studies and pilot-scale experiments, offering insights into EMF device design and tuning. The review concludes by identifying key research gaps and proposing integration strategies, such as combining EMF with low-dose antiscalants, to improve cost-effectiveness and scaling control efficiency. By clarifying underlying mechanisms and practical challenges, this review aims to reduce uncertainty and support broader adoption of EMF as a reliable, scalable, and sustainable solution for mineral scaling control.

The interaction of a turbulent Mach 5 boundary layer with blunt fins with leading edge sweep angles of 0deg, 15deg, and 30degis investigated in the Mach 5 shock tunnel at New Mexico State University. This paper reports on large-eddy simulations that were carried out in conjunction with the experiments. The approach boundary layer profile for the simulations was matched to femtosecond laser electronic excitation and tagging measurements in the shock tunnel experiments. The simulation for the unswept fin reveals a highly unsteady interaction region with a strong horseshoe vortex as dominant flow feature. In the mean, the flow separates 2.6 leading edge diameters upstream of the leading edge for the unswept fin and 2.1 and 1.3 leading edge diameters upstream of the leading edge for the fins with 15deg and 30deg sweep angle. Instantaneous flow visualizations reveal an intermittent breakup of the horseshoe vortex that goes hand in hand with strong wall pressure fluctuations. With increasing sweep angle, the horseshoe vortex becomes weaker, the upstream extent of the interaction region is reduced, and the interaction unsteadiness subsides. Instantaneous schlieren flow visualizations from the experiment are in qualitatively good agreement with the simulations. Root-mean-square distributions of the schlieren intensity and density fluctuations from the simulations share similar features.

Thin-film and slug calorimeters are essential for accurate heat flux measurements in hypersonic environments. While thin films are comparatively fragile and well suited for measuring high-frequency phenomena, slug calorimeters are rugged and appropriate for measuring large integral heat loads. A primary challenge in designing thin-film sensors lies in selecting an appropriate film thickness and accounting for heat loss from the film into the substrate. For slug calorimeters, heat loss into the surrounding insulator and through the back face introduces measurement inaccuracies. Simulations of the unsteady heat diffusion inside thin-film gauges and a novel bi-metal slug calorimeter were carried out. For the former, a laser heat source was assumed. For the latter, the heat flux was obtained from a thermo-chemical non-equilibrium simulation of Mach 18 air flow over a hemisphere. The frequency response of the thin-film to a box function and square wave heat flux input is inversely related to the film thickness. Minimal lateral contact of the thin film with the insulator can have a substantial impact on the frequency response. The slug calorimeter results reveal a 20% percent variation of the heat flux prediction depending on the wall catalycity. Inverse theory estimates of the heat flux from temperature measurements inside the slug are in good agreement with the known input data.

Electromagnetic field (EMF) treatment has emerged as a promising approach for scaling control due to its cost-effectiveness, simplicity, and low energy consumption. However, there is a limited understanding of the mechanisms by which applied EMF impacts mineral scaling in reverse osmosis (RO) systems. This has led to inconclusive and varied results and uncertainties regarding its effectiveness. This study elucidates the impacts of EMF on homogenous and heterogeneous nucleation and membrane performance during RO desalination of different feedwaters. Our results reveal that EMF exhibits greater efficacy in treating near-saturated water (SI similar to 0), especially when coupled with extended hydraulic flushing (HF). For saturated brackish water desalination, heterogeneous scaling predominantly occurs on membrane surfaces, with the effectiveness of EMF in inhibiting scaling primarily attributed to the hydration effect. In supersaturated solutions, EMF promotes bulk precipitation due to the magnetohydrodynamic effect, quickly blocking membrane pores. Thus, when the saturation reaches a certain high level during RO desalination, magnetohydrodynamic EMF effects can accelerate flux decline caused by homogeneous scaling. This work provides an efficient method for predicting EMF efficiency, emphasizing the importance of saturation conditions and HF cleaning duration in determining membrane performance, suggesting these show promise for improving undersaturated or near-saturated feedwater desalination via RO.

Using high-fidelity numerical simulations based on a lattice Boltzmann framework, the advection-enhanced transport of a passive scalar from a prolate spheroid in simple shear flow has been thoroughly investigated across various parameters, including the spheroid's aspect ratio, particle-to-fluid density ratio, Reynolds number (defined as ${\textit{Re}}=\textit{GR}<^>{2}/\nu$ , where $G$ is the flow shear rate, $R$ is the radius of a sphere of the same volume as the spheroid and $\nu$ is the kinematic viscosity of the fluid) and Schmidt number (defined as $\textit{Sc}=\nu /D$ , where $D$ is the diffusivity of passive scalar transport). The Reynolds number is constrained to the range of 0 <= Re <= 1, where the prolate spheroid tumbles around its minor axis, aligned with the vorticity axis, in an equilibrium state. Several key findings have emerged: (i) particle inertia significantly influences the uniformity of the spheroid's tumbling, affecting flow patterns around the spheroid and, consequently, the modes of scalar transport; (ii) both uniform and non-uniform tumbling generate a scalar line in the fluid with elevated scalar concentration, which sweeps through the wake region and merges with clusters of previously formed scalar lines; (iii) fluid passing over the spheroid carries the passive scalar downstream along these scalar lines; (iv) variations in the uniformity of spheroid tumbling result in distinct flow patterns and scalar transport modes, leading to different transport rates; (v) within the studied parameter ranges, increased particle inertia enhances the scalar transport rate; (vi) when particle inertia is minimal, the dimensionless scalar transport rate for different aspect ratios converges to a common dependence on the P & eacute;clet number. These phenomena are analysed in detail.