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This article presents methodological advances in the state-of-the-art for making time-dependent, thermochemical measurements within kilogram-scale explosive post-detonation fireballs utilizing tunable laser absorption spectroscopy. This measurement capability is critical for validating multi-scale, multi-physics models of post-detonation dynamics. The technique is based on hardened gauges built around rapidly-tunable lasers and custom post-processing algorithms that provide quantitative thermochemical data interior to large and opaque explosive fireballs. The authors present a holistic overview of the technique including gauge design, the laser absorption diagnostic, and the custom data processing algorithms. Additionally, fielding high-bandwidth laser absorption probes at stand-off ranges presents new challenges in data processing that must compensate for long distance signal transmission effects. We highlight representative data from a hardened gauge measurement at 0.81 m stand-off from a 2.78 kg LX-14 explosive charge detonated in an outdoor test arena. We discuss progress in all-optical measurement of temperature, pressure, and water vapor number density at a 100 kHz repetition rate during the first 10 ms of the fireball evolution. We conclude the article with a brief discussion on our current approach for comparing hardened gauge measurements with computational fluid dynamic simulations. [ABSTRACT FROM AUTHOR]

The compromise between inclusions removal by small bubbles and proper agitation of fluid flow in tundish by gas blown is challenging. The single‐strand tundish without flow control devices (bare tundish) is used to study the effects of side‐wall gas blowing on the flow field. The water model, particle image velocity measurement and computational fluid dynamics simulation are used to study bubble behavior, fluid flow field, and tracer transport. A large horse shoe vortex and a short circuit flow at the bottom are formed in the bare tundish. Gas blowing at the outlet‐side wall of the tundish creates multiple vortices in the right‐side region, with blowing rate and position greatly influencing the surface flow within the tundish. Gas blowing at the front‐side wall creates a large spiral vortex, agitating the fluid in the tundish and improving the flow field. Increasing the blowing rate strengthens the vortex in the right region, but raising the blowing position affects surface flow and creates a counterclockwise flow toward the shroud. In all schemes, gas blowing at a low position on the front‐side wall with a small gas flowrate is the optimized scheme which shows the smallest dead volume and enhances surface flow. [ABSTRACT FROM AUTHOR]

We exploit nonlinear elastodynamic properties of fractured rock to probe the micro‐scale mechanics of fractures and understand the relation between fluid transport and fracture aperture under dynamic stressing. Experiments were conducted on rough, tensile‐fractured Westerly granite subject to triaxial stresses. We measure fracture permeability for steady‐state fluid flow with deionized water. Pore pressure oscillations are applied at amplitudes ranging from 0.2 to 1 MPa at 1 Hz frequency. During dynamic stressing we transmit ultrasonic signals through the fracture using an array of piezoelectric transducers (PZTs) to monitor evolution of interface properties. We examine the influence of fracture aperture and contact area by conducting measurements at effective normal stresses of 10–20 MPa. Additionally, the evolution of contact area with stress is characterized using pressure sensitive film. These experiments are conducted separately with the same fracture and map contact area at stresses from 9 to 21 MPa. The measurements are a proxy for "true" contact area for the fracture surface and we relate them to elastic properties using the calculated PZT sensor footprints via numerical modeling of Fresnel zones. We compare the elastodynamic response of the fracture using the stress‐induced changes in ultrasonic wave velocities for transmitter‐receiver pairs to image spatial variations in contact properties. We show that nonlinear elasticity and permeability enhancement decrease with increasing normal stress. Additionally, post‐oscillation wave velocity and permeability exhibit quick recoveries toward pre‐oscillation values. Estimates of fracture contact area (global and local) demonstrate that the elastodynamic and permeability responses are dominated by fracture topology. Plain Language Summary: We perform laboratory experiments with fractured rock to understand the relation between fluid flow, fracture openness, and elastic properties under oscillating stresses. These experiments are conducted on rough, pre‐fractured granite specimens under normal stress conditions similar to those found in the shallow earth, a few kilometers in depth. Fluid pressure in the fracture is oscillated at various amplitudes at a fixed frequency. During this dynamic stressing, we use an ultrasonic device to monitor the evolution of the fracture interface. We examine the influence of fracture aperture and contact area by conducting measurements at increasing normal stress state. Additionally, the evolution of contact area with stress is characterized using pressure sensitive film, showing an image of where the two halves of the fracture are in contact. The ultrasonic monitoring reveals spatial variations in contact properties, which is informed by fracture contact area measurements. These measurements are also related to the fluid‐flow in response to dynamic stressing and similar comparisons are made for how the fracture interface evolves, recovers, following the stress perturbations. Key Points: Lab experiments to simulate fracture processes under dynamic stressingSimultaneous measurements of fluid flow and elastic wave properties to quantify elastodynamic and hydraulic responses to dynamic stressingLocal fracture aperture, not necessarily the stress state, dominates elastic and hydraulic responses to dynamic stressing [ABSTRACT FROM AUTHOR]

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is a routine method to noninvasively quantify perfusion dynamics in tissues. The standard practice for analyzing DCE-MRI data is to fit an ordinary differential equation to each voxel. Recent advances in data science provide an opportunity to move beyond existing methods to obtain more accurate measurements of fluid properties. Here, we developed a localized convolutional function regression that enables simultaneous measurement of interstitial fluid velocity, diffusion, and perfusion in 3D. We validated the method computationally and experimentally, demonstrating accurate measurement of fluid dynamics in situ and in vivo. Applying the method to human MRIs, we observed tissue-specific differences in fluid dynamics, with an increased fluid velocity in breast cancer as compared to brain cancer. Overall, our method represents an improved strategy for studying interstitial flows and interstitial transport in tumors and patients. We expect that our method will contribute to the better understanding of cancer progression and therapeutic response. [ABSTRACT FROM AUTHOR]

Various velocity measurements techniques for fluid dynamics experiments have been developed over the last four decades. These include Particle Image Velocimetry (PIV) and Particle Tracking Velocimetry (PTV), both of which rely on imaging the flow with passive particles. While these techniques now allow for an accurate determination of velocity fields at high particle densities, they still suffer from significant inaccuracies when it comes to measurements near boundaries, due to smaller particle concentrations and imaging difficulties in these regions. To improve such measurements, we developed a correction technique for measured velocity fields. Using a PTV approach, we reconstructed the 3D velocity field from an experimental setup designed to study Rayleigh–Bénard convection in a tank. We corrected the obtained velocity field to ensure its accurate, rigid boundary conditions corresponding to the tank walls, while keeping the flow divergence-free. We then assessed the quality of the corrected velocity fields by comparing them with the outputs of 3D numerical simulations that reproduced the precise experimental conditions. The experimentally obtained divergence-free velocity fields with exact boundary conditions compare well with the results of the numerical simulations, which validates our approach. Using synthetic images, we estimated that our corrected fields are in better agreement with numerical simulations (Pearson coefficient R = 0.96 ) than the raw measured fields (Pearson coefficient R = 0.91 ). We find that at high Reynolds numbers, our results can be described by scaling laws that are consistent with previous results from the literature. The correction technique could be useful for a wide range of fluid dynamics experiments where accurate measurements near the walls are needed. These include the advection of passive tracers, where the boundary conditions need to be exact, or turbulence measurements, where the flow gradient at the walls must be precisely determined. [ABSTRACT FROM AUTHOR]

This study investigates the impact of small water bodies on outdoor temperatures in their vicinity, using a campus located in the subtropical region of Taichung City, Taiwan, as the research subject. By employing on-site measurements and Computational Fluid Dynamics (CFD) simulations, we examined their temporal and spatial influence, as well as comparisons between actual measurements and software predictions. Key findings include the following: (1) Small water bodies exhibit discernible temperature-regulating effects on their surrounding areas. While the influence diminishes with distance, this attenuation is not stark, and is potentially constrained by the water body's patch size. (2) Regulatory effects vary between day and night. In summer, temperature reductions of up to 3.5 °C (simulated) and 3.2 °C (measured) were observed. Conversely, in winter, daytime temperatures around water bodies may rise by up to 3.9 °C. (3) Discrepancies between CFD simulations and actual measurements, influenced by fluctuations in Global Horizontal Irradiation (GHI), range from +2.5 °C to −1.8 °C. During high GHI periods, measured values surpass simulations, whereas during low or zero GHI conditions, simulations exceed measurements. Moreover, high regression analysis R2 values validate the feasibility of CFD simulations for predicting water body-induced temperature changes. Insights from this study offer valuable guidance for urban planners and policymakers seeking sustainable urban climate management strategies. [ABSTRACT FROM AUTHOR]

We observe and measure the nonequilibrium dynamics of optical vortices as a function of propagation distance through a nonlinear medium. The precession of a tilted-core vortex is quantified as is vortex core sharpening, where the infinite width of a linear core subsequently shrinks and approaches the healing length of this nonlinear optical fluid. Experiments are performed with a variable-length nonlinear medium: a nonlinear fluid in a tank with an output window on a translating tube. This provides control over the distance the light propagates in the fluid and allows for the measurement of the dynamics throughout the propagation range. Results are compared with the predictions of a computational simulator to find the equivalent dimensionless nonlinear coefficient. [ABSTRACT FROM AUTHOR]

Diabetes mellitus is one of the key diseases of clinical concern that can lead to a variety of serious complications and it is characterized by increased blood glucose levels. Glucose‐sensitive hydrogel is gaining attention as a smart hydrogel capable of sensing glucose molecules for diabetes and related complications. In order to better understand this hydrogel, this paper reviews its basic design principles and focuses on the therapeutic efficacy of this hydrogel in delivering insulin, drugs, and bioactives for diabetes and diabetes‐related complications. Its use as a biosensing device for glucose measurement in body fluids and dynamic monitoring of wounds is also presented, and its potential application in the treatment of diabetes and related diseases is highly summarized. [ABSTRACT FROM AUTHOR]

Ultrasonic anemometers mounted on rotary-wing drones have the potential to provide a cost-efficient alternative to the classical meteorological mast-mounted counterpart for wind energy applications. However, the propeller-induced flow may deteriorate the accuracy of free wind velocity measurements by wind sensors mounted on the drone. Therefore, we performed an experiment using three short-range continuous-wave Doppler lidars (DTU WindScanners) to measure the complex and turbulent three-dimensional wind field around a hovering drone at low ambient wind speeds. The results obtained by lidar measurements and computational fluid dynamics simulations are in good agreement. Both methods conclude that the disturbance zone on a horizontal plane 0.7 meters below the drone, extends about 2 meters upstream from the drone center for the horizontal wind velocity and more than 5 meters for the vertical wind velocity. By comparing wind velocities along horizontal lines in the upstream direction, we find that the velocity difference between the two methods is less than 0.1 ms−1 in most cases. Both plane and line scan results validate the reliability of simulations. Furthermore, simulations of flow patterns in a vertical plane at low ambient speed indicate that it is difficult to accurately measure the vertical wind component with less than 1 % distortion by drone-mounted sonic anemometers. [ABSTRACT FROM AUTHOR]

Stirred tanks are widely used in various industrial processes for mixing, and reactions understanding the flow behavior and optimizing the impeller design is crucial for improving mixing efficiency and product quality. This paper investigates the radial velocity profiles near the impeller tip in a baffled stirred tank using experimental measurements and computational fluid dynamics (CFD) simulations. A cylindrical tank with four baffles was used with four impeller types—anchor, counterflow, sawtooth, and Rushton turbine. The simulations utilized the k-omega turbulence model and the Reynolds stress model with a momentum source term to model the impeller. The results indicate that both the models predict the maximum radial velocities accurately compared to experiments capturing the flow behavior near the impeller edge. Double turbine impellers generate localized turbulence around the blade tip, while pitched blade turbines with down-pumping produce high-intensity turbulence zones throughout the tank. CFD velocity vector plots provide further insight into discharge flows and circulation patterns. The proposed momentum source term approach aligned closely with experimental data and performed better than multiple reference frame methods. [ABSTRACT FROM AUTHOR]

In this work, an integrated optofluidic phase-shifting element, along with an image processing algorithm, was proposed to enable quantitative analysis for microfluidic applications using a digital holographic microscopic configuration. The advantages of the proposed system lie in its compactness, that the phase-shifting element can be simultaneously fabricated with other microfluidic functional components on a single chip, its robustness to resist environmental vibrations as no mechanical movement is involved for phase-shifting, and its capability of capturing transient events of fluid dynamics for quantitative measurement. The performance of the proposed system was validated with quantitatively label-free monitoring of concentration gradients under various conditions in microchannels. [ABSTRACT FROM AUTHOR]

The simulated moving bed (SMB) is a well-established, fully continuous process for chromatographic separation of difficult tasks with overlapping peaks, but it is relatively complex. The 1-SMB, which uses only one column but includes residence time zones to preserve concentration profiles, is a simpler semi-continuous alternative. This work examines the possible design of these residence time zones. Simulation studies were conducted to investigate the dependence of process metrics, such as purity, yield, productivity, and eluent consumption, on fluid dynamics. No deterioration in purity was observed, and the other variables remained constant over a wide range of axial dispersion before decreasing sharply. Pilot-scale experiments were conducted with various devices, including coiled flow inverters, eluate recycling devices, packed columns, and tank arrangements, to validate possible apparatus implementations with fluid dynamic measurements. It was demonstrated that the 1-SMB offers similar performance to the 4-SMB, albeit with reduced yield and lower apparatus complexity. [ABSTRACT FROM AUTHOR]

In this study, the potential of a low-cost bio-adsorbent, taken directly from Date Palm Trunk Fibers (DPTF) agricultural wastes, for cadmium ions removal from wastewaters is examined. The performances of this adsorbent are evaluated by building breakthrough curves at different bed heights and flow rates while keeping other parameters, such as the initial feed concentration, pH, and particle size, constant. The results indicate that the maximum cadmium adsorption capacity of DTPF can be obtained from the Thomas model as 51.5 mg/g with the most extended mass transfer zone of 83 min at the lowest flow rate at 5 ml/min. The saturation concentrations (NO) and the rate constant (kab) obtained from the BDST (bed depth service time) model are 7022.16 mg/l and 0.0536 l/mg.min, respectively. Using the Yon-Nelsen Model, it is found that operating at a lower flow rate leads to a larger value of the elapsed needed time to reach a 50% breakthrough. The Wolborska model indicates that the bed capacity increases with decreasing the flow rate, and the adsorbent can achieve a greater external mass transfer kinetic coefficient (2.271/min) at a higher flow rate. [ABSTRACT FROM AUTHOR]

OBJECTIVES: Right ventricle to pulmonary artery anatomic discontinuity is common in complex congenital heart malformations. Handsewn conduits are a practised method of repair. In a proof-of-concept study, we evaluated pulmonary valve replacement with a handsewn pericardial valved pulmonary conduit in vitro and in vivo. METHODS: A pulsatile flow-loop model (in vitro) and an acute 60-kg porcine model (in vivo) were used. With echocardiography and pressure catheters, baseline geometry and fluid dynamics were measured. The pulmonary valve was replaced with a handsewn glutaraldehyde-treated pericardial valved pulmonary conduit corresponding to a 21-mm prosthetic valve, after which geometric measurements and fluid dynamics were reassessed. RESULTS: In vitro, 15 pulmonary trunks at 4 l/min and 13 trunks at 7 l/min, and in vivo, 11 animals were investigated. The valved pulmonary conduit was straightforward to produce at the operating table and easy to suture in place. All valves were clinically sufficient in vitro and in vivo. The mean transvalvular pressure gradient in the native valve and the conduit was 8 mmHg [standard deviation (SD): 2] and 7 mmHg (SD: 2) at 4 l/min in vitro, 19 mmHg (SD: 3) and 17 mmHg (SD: 4) at 7 l/min in vitro and 3 mmHg (SD: 2) and 6 mmHg (SD: 3) in vivo. CONCLUSIONS: Our proof-of-concept demonstrates no early evidence of structural damage to the conduit, and the fluid dynamic data were acceptable. The handsewn conduit can be produced at the operating table. Conduits to restore the right ventricle to pulmonary artery (RV–PA) anatomic discontinuity are used routinely in complex congenital malformations that involve the right ventricular outflow tract. [ABSTRACT FROM AUTHOR]

Pressure swirl nozzles are widely applied in spray cooling, dust removal, and fuel injection. To better connect the nozzle structure with the internal flow to analyze their influence on spray parameters, this paper designs a nozzle structure and uses experimental measurement and computational fluid dynamics simulation methods to investigate the influence of the nozzle's tangential velocity to axial velocity ratio (vτin/vzin) and the swirl diversion channel eccentric distance (dl) on the spray parameters. A phase Doppler particle analyzer was used in the experiment study to determine the spray axial velocity (vz) and sault mean diameter (D32). In the simulation investigation, the Eulerian multiphase flow model was used to calculate the multiphase flow field of the spray. The results showed that dl and vτin/vzin both have an obviously linear relationship to the peak location (rpeak) of each spray parameter. It means that dl plays similar roles as the vτin/vzin, which can enhance the swirl strength inside the nozzle and increase the spray cone angle. The rpeak of liquid phase volume fraction (αw) and D32 of the droplet particle are always greater than the rpeak of vz. The analysis of the flow field inside the spray orifice indicates that as the vτin/vzin rises, the liquid in the nozzle orifice tends to move farther from the central axis, causing atomization to occur more upstream. This study serves as a reference for the flow analysis and structure design of the pressure swirl nozzle. [ABSTRACT FROM AUTHOR]

Based on the European Union Basic Safety Standards to protect people against exposure to ionizing radiation, establishing and addressing the reference levels for indoor radon concentrations is necessary. Therefore, the indoor radon concentration should be monitored and control in dwelling and workplaces. However, proper ventilation and sustainability are the major factors that influence how healthy the environment in a building is for its occupants. In this paper, the indoor radon distribution in a typical naturally ventilated room under two scenarios (when the door is closed and open) using the computational fluid dynamics (CFD) technique was studied. The CFD code ANSYS Fluent 2020 R1 based on the finite volume method was employed before the simulation results were compared with analytical calculations as well as passive and active measurements. The average radon concentration from the CFD simulation was found to be between 70.21 and 66.25 Bq m−3 under closed and open-door conditions, respectively, at the desired ventilation rate of 1 ACH (Air Changes per Hour). Moreover, the highest concentrations of radon were measured close to the floor and the lowest values were recorded near to the inlet, resulting in the airflow velocity profile. The simulation results were in good agreement with the maxima of 19% and 7% compared to analytical calculations at different indoor air velocities in the open- and closed-door scenarios, respectively. The measured radon concentrations obtained by the active measurements also fitted well with the CFD results, for example, with a relative standard deviation of around 7% and 2% when measured by AlphaGUARD and RAD7 monitors at a height of 1.0 m above the ground in the open-door scenario. From the simulation results, the effective dose received by an individual from the indoor air of the workplace was also calculated. [ABSTRACT FROM AUTHOR]

To improve the recovery rate of clean coal, a liquid–solid fluidised bed is typically used to process coarse coal slime of 0.25–1.5 mm. In this paper, a combination of experimental measurements and computational fluid dynamics (CFD) simulations was used. The fluidisation behaviour of four groups of coarse coal particles with different sizes and densities in a fluidised bed with rectangular cross-section was investigated. The Euler–Euler method, shear stress transport k–ω turbulence model, kinetic theory of granular flow (KTGF) and modified Gidaspow drag model were used for CFD simulations. The experiment and CFD simulation results showed that when J L /U mf was greater than 1, the expansion ratio of the fluidised bed of coarse coal particles varied as a power function of the J L /U mf value. The bed expansion ratio model developed by Tripathy et al. in a fluidised bed with a circular cross-section was also applicable to a fluidised bed with a rectangular cross-section. The pressure drop data at different heights indicated that the measured values showed a linear pattern with the measured height. This indicated that when J L /U mf was greater than 1, the coarse coal particles showed a uniform fluidisation characteristic. After choosing appropriate initial conditions and models, the CFD simulation agreed well with the experimental data. The experimental data and simulation results can deepen the understanding of liquid–solid fluidised beds of coarse coal particles, which is beneficial to improve the fluidisation quality of the fluidised bed and further improve the separation effect. [Display omitted] • Coarse coal particle fluidisation is investigated by experimental and CFD approach. • Bed expansion ratio varies as a power function of the J L /U mf value greater than 1. • The pressure drop at different levels is linearly related to the measured height. • The bed expansion ratio model is applied to the rectangular fluidised bed. [ABSTRACT FROM AUTHOR]

It is challenging to estimate the air exchange rate (AER) dynamically in naturally ventilated livestock buildings such as dairy houses due to the influence of complex and variable outdoor environmental factors, large opening ratios, and the confusion of inflow and outflow at openings. This makes it difficult to efficiently regulate the opening ratio to meet the ventilation requirements in naturally ventilated livestock buildings. In this study, the air exchange rates of naturally ventilated cattle houses (NVCHs) in different seasons and opening ratios were obtained through field measurements and computational fluid dynamics (CFD) simulations. A fast and efficient machine learning framework was proposed and examined to predict AER based on the gradient boosting decision tree (GBDT) combined with Bayesian optimization. Compared with commonly used machine learning models such as multilayer perceptrons (MLPs) and support vector machines (SVMs), the proposed GBDT model has higher prediction accuracy and can avoid falling easily into local optima. Compared with the existing mechanical model based on the Bernoulli equation, the proposed GBDT model showed a slightly higher prediction than the mechanistic model and was much easier to use in AER estimation when inputting easily collected environmental factors in practical applications. Using Bayesian optimization could dramatically reduce the computing time when determining the optimal hyperparameter for establishing the GBDT model, dramatically saving on computing resources. Based on the Bayesian optimized GBDT model, the desirable opening ratio of the side curtain can be determined for automatically regulating the AER of cattle houses in future applications. [ABSTRACT FROM AUTHOR]

In Japan, natural disasters have historically caused massive damage, and the importance of emergency temporary housing is increasing. In this paper, the summer thermal environment at the Shirahata temporary housing site in Kousa Town was assessed. The site was constructed following the 2016 Kumamoto Earthquake. The site was improved by applying a design methodology called "Kumamoto Type D," "D" stands for "Default & Design." Field measurements and computational fluid dynamics simulations were conducted to investigate the influence of the building arrangement on the outdoor thermal environment for the Kumamoto Type D layout. The results indicated that the impact of wind was reduced using this layout. However, when the surface temperature in the parking lot and other areas increased, hot air could be transmitted to the site, even under reduced wind conditions. [ABSTRACT FROM AUTHOR]

Introduction: Direct quantification of hemodynamic factors applied to a cerebral aneurysm (CA) remains inaccessible due to the lack of technologies to measure the flow field within an aneurysm precisely. This study aimed to develop an in vitro validated 3D in silico patient-specific internal carotid artery sidewall aneurysm (ICASA) model which can be used to investigate hemodynamic factors on the CA pathophysiology. Methods: The validated ICASA model was developed by quantifying and comparing the flow field using particle image velocimetry (PIV) measurements and computational fluid dynamics (CFD) simulations. Specifically, the flow field characteristics, i.e., blood flowrates, normalized velocity profiles, flow streamlines, and vortex locations, have been compared at representative time instants in a cardiac pulsatile period in two designated regions of the ICASA model, respectively. One region is in the internal carotid artery (ICA) inlet close to the aneurysm sac, the other is across the middle of the aneurysmal sac. Results and Discussion: The results indicated that the developed computational fluid dynamics model presents good agreements with the results from the parallel particle image velocimetry and flowrate measurements, with relative differences smaller than 0.33% in volumetric flow rate in the ICA and relative errors smaller than 9.52% in averaged velocities in the complex aneurysmal sac. However, small differences between CFD and PIV in the near wall regions were observed due to the factors of slight differences in the 3D printed model, light reflection and refraction near arterial walls, and flow waveform uncertainties. The validated model not only can be further employed to investigate hemodynamic factors on the cerebral aneurysm pathophysiology statistically, but also provides a typical model and guidance for other professionals to evaluate the hemodynamic effects on cerebral aneurysms. [ABSTRACT FROM AUTHOR]

Secondary calibration systems and long-term stable reference sensors are needed to meet the industry requirements and, thus, to take the necessary steps from static to dynamic calibrations with significantly improved accuracy and reliability of dynamical measurements. The calibration of the reference transducer was found to be the dominant uncertainty source and therefore further improvement of the calibrator uncertainty mainly relies on advancements in the primary calibration methods. Keywords: Dynamic measurements; dynamic pressure; secondary pressure standard; dynamische Messungen; dynamischer Druck; Sekundärdrucknormal EN Dynamic measurements dynamic pressure secondary pressure standard DE dynamische Messungen dynamischer Druck Sekundärdrucknormal 721 728 8 09/26/22 20221001 NES 221001 1 Introduction A variety of measurements of mechanical quantities like force, torque and pressure in industries such as automotive, marine, aerospace, wind power plants, manufacturing, process control and safety testing are of a dynamical nature [[1]], [[2]]. Trapped air bubbles in the pressure chamber and in the channels of the pressure transducers under test have been found to introduce large measurement errors and to alter the shape and duration of the pressure pulse due to a change in the compressibility of the hydraulic system. [Extracted from the article]

[Display omitted] • The annular swirling flow reactor excels in liquid–liquid mixing. • Conical structure effectively inhibits attenuation of swirling flow intensity. • Main mass transfer region of the reactor is near the central conical wall. • The swirling flow reactor exhibits superior crystal preparation capability. • In reaction crystallization, the swirling flow reactor shows unique potential. This study investigates the performance of an annular conical swirling flow reactor in liquid–liquid reactions for the preparation of inorganic salt particles. Utilizing Particle Image Velocimetry (PIV) measurements and Computational Fluid Dynamics (CFD) simulations, it was observed that the conical design effectively inhibited the attenuation of swirling flow intensity along the axial direction, with the primary mass transfer region close to the central conical wall. In comparison to a stirred reactor, calcium carbonate particles synthesized in the swirling flow reactor exhibited more uniform morphology, smoother and defect-free surface. Notably, the average particle size remained consistently within 5–6 μm (excluding the 0.3 M feedstock), whereas stirring led to particles with an average size ranging from 8-11 μm. Analysis of the residence time distribution curve revealed minimal back mixing in the swirling flow reactor, ensuring nearly equal growth time for salt particles, thus yielding particles with a uniform size distribution. As a result, the swirling flow reactor presents compelling prospects for applications in reactive crystallization. [ABSTRACT FROM AUTHOR]

This work investigates the husbandry microenvironment and health status of experimental mice to help create a suitable husbandry microenvironment for experimental animals, with the aim of ensuring the quality and animal welfare of experimental mice through a suitable husbandry microenvironment. Experimental measurements and computational fluid dynamics (CFD) are used to analyze the husbandry microenvironment of experimental mice, and indicators for judging the health status and husbandry microenvironments of experimental mice are proposed. The results show that the correlation between the health state of mice and abdominal heat flux reaches 0.786 (p = 0.01), and there is a significant difference between the environmental evaluation indexes of healthy and sick mice. The relationship between the mice and the husbandry microenvironments could be characterized by the C bs number, i.e.，C bs number is defined as the biological surface convective heat transfer number of the microenvironment, and the value of C bs number of the healthy mice could be referred to as about 0.3334. This is of guiding significance for the judgment of the health of experimental animals and the creation of a suitable husbandry microenvironment for experimental animals. • Investigate the correlation between mice's abdominal heat flux and health status. • Propose an indicator C bs number for judging the husbandry microenvironment. • Reflect the relationship between the microenvironment and mice heat dissipation. [ABSTRACT FROM AUTHOR]

We investigate the fluid dynamics of a microturbine system that is applied in a device for chemical and biological analysis--a so-called magic angle spinning (MAS) nuclear magnetic resonance (NMR) probe. The present system is utilized in a wide temperature range from 45 K to 293 K. Pressurized air, nitrogen, or helium are used to drive a Pelton type microturbine. This turbine is mounted on a MAS rotor with a diameter between 0.7 mm and 3.2 mm. The rotor system is equipped with a pressurized gas bearing that is operated by the same gas species as the turbine. Computational fluid dynamics (CFD) simulations have been performed and compared with fluid dynamics measurements of the MAS system for different diameters, temperatures, and spinning rates between 23 kHz and 120 kHz. To our knowledge, this work is the first comprehensive CFD and experimental study of such a wide temperature range that has been carried out for microturbines with pressurized gas bearings. The results show good agreement between measurements and CFD simulations with appropriate (real) gas models, i.e., the ideal gas model for air at room temperature, Peng-Robinson model for nitrogen at 105 K, and ideal gas model for helium at 45 K. [ABSTRACT FROM AUTHOR]

Airflow improvement in a large industrial building is one of the most effective ways to improve the thermal comfort of workers. Air Diffusion Performance Indices (ADPI) of an industrial workshop area under different air supply angles (15°, 30°, 45°, 60°, 75° and 90° in summer and 90° in winter) of the ceiling-mounted swirling diffusers were evaluated by on-site measurements and computational fluid dynamics (CFD) modelling. The measurement data was used to verify the CFD numerical model. The temperature and velocity field of the working area were simulated and analysed under seven operating conditions of swirling diffusers. The findings showed that in summer, the increase of the swirling air supply angle would increase the air velocity. When the air supply angle was larger than 75°, a draughty wind speed (>0.3 m/s) in the local working area, was produced. When the air supply angle was 30°–75°, the indoor design comfortable temperature range (26°C–28°C) was produced. The ADPIs of the workshop were 100% with the air supply angles of 45° and 60° in summer and 90° in winter, respectively. The research findings should provide a reference for improving the airflow organization in the working area of a tall factory building. [ABSTRACT FROM AUTHOR]

Turbulence is one of the ubiquitous aspects of aquatic systems and affects many physical and biological processes. Based on direct velocity measurements and a computational fluid dynamics (CFD) simulation, we characterized the distribution of the turbulent kinetic dissipations rates (ε) in an orbital shaker system within a range of rotation frequencies. CFD was able to estimate the ε distribution in containers accurately, which was confirmed by other two methods and was independent of velocity measurement. The results showed that ε was linearly correlated with the rotational frequencies. Despite the existence of gradients of ε and the fact that a mean circular horizontal flow was formed within the tank, the energy levels of the whole tank varied spatially within an order of magnitude and the ε distributions at different rotational frequencies were similar, suggesting that the ε distribution in the whole tank could be seen as quasi-homogeneous. To investigate the influence of turbulence on algae growth, culture experiments of a typical diatom—Skeletonema costatum were carried out under different turbulence conditions. Our results suggested turbulence mixing promoted nutrient uptake and growth of Skeletonema costatum, which could be attributed to the break of the diffusion-limited resource concentration boundary layer surrounding phytoplankton. [ABSTRACT FROM AUTHOR]

Purpose: This research aims to present an aero-propulsive interaction model applied to conceptual aircraft design with distributed electric propulsion (DeP). The developed model includes a series of electric ducted fans integrated into the wing upper trailing edge, taking into account the effect of boundary layer ingestion (BLI). The developed model aims to estimate the aerodynamic performance of the wing with DeP using an accurate low-order computational model, which can be easily used in the overall aircraft design's optimization process. Design/methodology/approach: First, the ducted fan aerodynamic performance is investigated using a low-order computational model over a range of angle of attack required for conventional flight based on ducted fan design code program and analytical models. Subsequently, the aero-propulsive coupling with the wing is introduced. The DeP location chordwise is placed at the wing's trailing edge to have the full benefits of the BLI. After that, the propulsion integration process is introduced. The nacelle design's primary function is to minimize the losses due to distortion. Finally, the aerodynamic forces of the overall configuration are estimated based on Athena Vortex Lattice program and the developed ducted fan model. Findings: The ducted fan model is validated with experimental measurements from the literature. Subsequently, the overall model, the wing with DeP, is validated with experimental measurements and computational fluid dynamics, both from the literature. The results reveal that the currently developed model successfully estimates the aerodynamic performance of DeP located at the wing trailing edge. Originality/value: The developed model's value is to capture the aero-propulsive coupling accurately and fast enough to execute multiple times in the overall aircraft design's optimization loop without increasing runtime substantially. [ABSTRACT FROM AUTHOR]

Aerodynamic performances of ground vehicle continuously improve and a lot of both wind tunnel measurements and Computational Fluid Dynamics (CFD) investigations contribute in the identification of local zones where shape deformation can lead to drag force reduction. Gradient-based optimization with optimal system involving CFD models is one of the powerful methods for shape optimization, but a genetic algorithm applied on the surrogate model can also explore a large design space in a reasonable period of computation time. In this paper, we present an aerodynamic optimization technique using a Kriging model in order to perform CFD simulations of different front air dam geometries situated below the front bumper of a reduced scale road vehicle. A first design-of-experiment (DoE) is undertaken with Large Eddy Simulations (LES), involving height geometric parameters for radial-basis-function of the front air dam, utilizing a Sobol algorithm. Then, a multi-objective-genetic-algorithm (MOGA) is applied on the constituted surrogate model, depending on the geometric parameters of the front air dam, in order to reach a minimum drag coefficient value by considering pressure constraints. Results show that a front air dam can increase the pressure at the rear of the tailgate, especially by slowing the airflow below the underfloor, but an optimum balance is necessary in order to not increase the stagnation pressure on the air dam, leading to the loss of this benefit. The Sobol technique driven by the Kriging model enables the retrieval of optimum airdam shapes found with wind tunnel tests, even with relatively coarse numerical meshes used for CFD simulations. [ABSTRACT FROM AUTHOR]

Hearing is a fundamental sense of many animals, including all mammals, birds, some reptiles, amphibians, fish, and arthropods. The auditory organs of these animals are extremely diverse in anatomy after hundreds of millions of years of evolution, yet all are made up of cellular tissue and are morphologically part of the bodies of animals. Here, we show that hearing in the orb-weaving spider Larinioides sclopetarius is not constrained by the organism's body but is extended through outsourcing hearing to its extended phenotype, the proteinaceous, self-manufactured orb web. We find that the wispy, wheel-shaped orb web acts as a hyperacute acoustic antenna to capture the sound-induced air particle movements that approach the maximum physical efficiency better than the acoustic responsivity of all previously known eardrums. By sensing the motion of web threads, the spider remotely detects and localizes the source of an incoming airborne acoustic wave, such as those emitted by approaching prey or predators. By outsourcing its acoustic sensors to its web, the spider is released from body size constraints and permits the araneid spider to increase its sound-sensitive surface area enormously, up to 10,000 times greater than the spider itself. The spider also enables the flexibility to functionally adjust and regularly regenerate its external "eardrum" according to its needs. The outsourcing and supersizing of auditory function in spiders provides unique features for studying extended and regenerative sensing and designing novel acoustic flow detectors for precise fluid dynamic measurement and manipulation. [ABSTRACT FROM AUTHOR]

We present a study on the spall strength of additive manufactured (AM) Ti-6Al-4V. Samples were obtained from two pieces of selective laser melted (SLM, a powder bed fusion technique) Ti-6Al-4V such that the response to dynamic tensile loading could be investigated as a function of the orientation between the build layers and the loading direction. A sample of wrought bar-stock Ti-6Al-4V was also tested to act as a baseline representing the traditionally manufactured material response. A single-stage light gas-gun was used to launch a thin flyer plate into the samples, generating a region of intense tensile stress on a plane normal to the impact direction. The rear free surface velocity time history of each sample was recorded with laser-based velocimetry to allow the spall strength to be calculated. The samples were also soft recovered to enable post-mortem characterization of the spall damage evolution. Results showed that when the tensile load was applied normal to the interfaces between the build layers caused by the SLM fabrication process the spall strength was drastically reduced, dropping to 60% of that of the wrought material. However, when loaded parallel to the AM build layer interfaces the spall strength was found to remain at 95% of the wrought control, suggesting that when loading normal to the AM layer interfaces, void nucleation is facilitated more readily due to weaknesses along these boundaries. Quasi-static testing of the same sample orientations revealed a much lower degree of anisotropy, demonstrating the importance of rate-dependent studies for damage evolution in AM materials. [ABSTRACT FROM AUTHOR]

Process analytical technology (PAT) has developed significantly since its introduction in pharma where many in situ analytical probes and measuring devices are now commercially available, replacing the use of off-line quality control measurements that are typically laborious and time intensive. The use of PAT instrumentation should not interfere with the process itself and subsequently should have no effect on the product whilst measuring representative samples. Implementation of these devices is typically arbitrary using empirical means. Therefore, the objective of this study is to highlight the use of computational fluid dynamics modeling to investigate the effect of interfacing parameters and process parameters of an inline near-infrared (NIR) probe used to determine the viscosity of a non-Newtonian micellar liquid. The parameters investigated for the probe were immersion depth, immersion angle, gap size, and fluid velocity. The results conclude that the immersion angle and depth should both be optimized to prevent stagnant fluid accumulating in the measuring gap ensuring that the NIR measurements are representative of the bulk. The gap size determines the optical pathlength and therefore was also investigated against an existing predictive viscosity model showing no changes in model performance with varying gap size. The use of computational modeling to develop a digital twin prior to PAT implementation at the equipment design stage ensures the technology can perform at its best and will also aid in calibration transfer studies. Graphical Abstract [ABSTRACT FROM AUTHOR]

Mechanical degradation by shear is one of the mechanisms that limits the life-time of lubricating grease in a rolling bearing. It results in a change of the micro-structure of the thickener–oil system, leading to a change in bleed and consistency. The resistance to degradation can be quantified using a grease worker. In this article, a novel approach is described, where the grease worker is used to measure the rheological properties of a grease in situ, while aging the grease. Mechanical energy and pressure losses are calculated using the measured force that is required to push the plate with holes through the grease in the cylinder of the grease worker. A pipe flow model in combination with a power law rheology model are used to analytically determine the power law fluid consistency index and exponent while aging the grease. The model validity is verified using computational fluid dynamics simulations and measurements using a rheometer with plate–plate geometry. [ABSTRACT FROM AUTHOR]

We present novel in‐field vegetation fire observations and the analyses using brightness temperatures recorded by longwave infrared camera and thermal image velocimetry. The brightness temperatures from a wind‐driven stubble wheat fire were obtained with a 60 frames per second (fps) video acquisition. Multi‐level sonic anemometers on a 10m in‐fire tower were used for measurements of turbulent velocity and air temperatures, while fuel level air and flame temperatures were collected by an array of thermocouples (TCs). The camera's image pixel resolution was adequate to discern thermal structures in accordance with the in‐fire TC measurements and its spacing distances. The in‐situ and remotely measured flaming zone dynamics were derived using two different methodologies, Thermal Image Velocimetry (TIV) and Image Segmentation (IS). The results highlight spatial and spectral information of coherent turbulent and mean velocity structures. The power spectra decomposition of the TIV showed similar spectral characteristics to the sonic speed measurements during the fire passage under the tower with a similar inertial subrange slope. This result reveals plausible evidence of interaction between the flaming zone and wind turbulence for a prescribed rapidly moving stubble wheat fire. This research presents a new field measurement methodology for understanding fire‐atmospheric interactions between the flaming zone and the immediate overlying atmospheric turbulent boundary layer. Plain Language Summary: The size and destructive power of wildfires can vary depending on weather and fuel conditions. We have carried out wheat stubble burning experiments using specialized instrumentation in order to study how the wind and fire interact, and the subsequent role of this interaction in the development of an experimental field‐scale burn. We used Long‐Wave InfraRed or LWIR cameras to capture radiation emitted by the fire but invisible to the human eye. We then used the time‐sequenced LWIR images to detect and calculate forward motion and fluctuation of the fire. We demonstrated for the first time the validity of these techniques by comparing the results with wind measurements collected during the passage of the fire using sonic anemometers. This new observation method has provided the first set of two‐dimensional observations of the interaction between the flame zone and the overlying wind. Key Points: A near target cooled infrared camera captures spatial fire thermal perturbations verified with an onsite thermocouple sensor arrayTurbulence derived from Thermal Image Velocimetry of flaming zone reveals similar spectral characteristics with atmospheric measurements [ABSTRACT FROM AUTHOR]

The influence of waveguide tubes on the signals received by remote pressure sensors measuring pressure histories in pulsed detonation engines (PDEs) and rotating detonation engines (RDEs) is studied computationally. Two types of pressure sensors are considered: low-frequency static pressure sensors and high-frequency sensors of pressure pulsations. Three approaches to solving the problem are used: based on Euler (inviscid flow), Navier–Stokes (laminar flow), and unsteady Reynolds-averaged Navier–Stokes (turbulent flow) equations. The approaches based on the inviscid and laminar flow models are shown to provide the best predictive capability. The laminar flow model is applied to analyzing the readings of pressure sensors installed remotely in the waveguide tubes attached to the hydrogen-fueled PDE, RDE, and detonation ramjet (DR). It is shown that the measurements of static pressure and pressure pulsations by remote pressure sensors do not correspond to the time-averaged mean and local instantaneous values of pressure in the combustors. The pressure time histories can be recovered based on the measurements and computational fluid dynamics calculations of the operation process. The latter is demonstrated by analyzing the results of test fires with a dual-duct DR model. [ABSTRACT FROM AUTHOR]

As oil exploitation enters its middle and late stages, formation pressure drops, and crude oil degases. In production profile logging, the presence of the gas phase will affect the initial oil–water two-phase flowmeter's flow measurement results. In order to eliminate gas-phase interference and reduce measurement costs, we designed a downhole gas–liquid separator (DGLS) suitable for low flow, high water holdup, and high gas holdup. We based it on the phase isolation method. Using a combination of numerical simulation and fluid dynamic measurement experiments, we studied DGLS separation efficiency separately in the two cases of gas–water two-phase flow and oil–gas–water three-phase flow. Comparative analysis of the numerical simulation calculation and dynamic test results showed that: the VOF model constructed based on k − ε the equation is nearly identical to the dynamic test, and can be used to analyze DGLS separation efficiency; the numerical simulation results of the gas–water two-phase flow show that when the total flow rate is below 20 m3/d, the separation efficiency surpasses 90%. The oil–gas–water three-phase's numerical simulation results show that the oil phase influences separation efficiency. When the total flow rate is 20 m3/d–50 m3/d and gas holdup is low, the DGLS's separation efficiency can exceed 90%. Our experimental study on fluid dynamics measurement shows that the DGLS's applicable range is when the gas mass is 0 m3/d~15 m3/d, and the water holdup range is 50%~100%. The research presented in this article can provide a theoretical basis for the development and design of DGLSs. [ABSTRACT FROM AUTHOR]

The recent outbreak of the COVID-19 causes significant respirational health problems, including high mortality rates worldwide. The deadly corona virus-containing aerosol enters the atmospheric air through sneezing, exhalation, or talking, assembling with the particulate matter, and subsequently transferring to the respiratory system. This recent outbreak illustrates that the severe acute respiratory syndrome (SARS) coronavirus-2 is deadlier for aged people than for other age groups. It is evident that the airway diameter reduces with age, and an accurate understanding of SARS aerosol transport through different elderly people's airways could potentially help the overall respiratory health assessment, which is currently lacking in the literature. This first-ever study investigates SARS COVID-2 aerosol transport in age-specific airway systems. A highly asymmetric age-specific airway model and fluent solver (ANSYS 19.2) are used for the investigation. The computational fluid dynamics measurement predicts higher SARS COVID-2 aerosol concentration in the airway wall for older adults than for younger people. The numerical study reports that the smaller SARS coronavirus-2 aerosol deposition rate in the right lung is higher than that in the left lung, and the opposite scenario occurs for the larger SARS coronavirus-2 aerosol rate. The numerical results show a fluctuating trend of pressure at different generations of the age-specific model. The findings of this study would improve the knowledge of SARS coronavirus-2 aerosol transportation to the upper airways which would thus ameliorate the targeted aerosol drug delivery system. [ABSTRACT FROM AUTHOR]

Estimates of the sub‐seabed fluid flow rates are important for understanding hydrological budgets, biogeochemical cycles, and physical properties of the sediments. Fluid flow rates and directions, however, are difficult to measure, particularly beneath the seafloor. We developed a rapid method to estimate regional fluid migration rates using an extensive database of seismic reflection profiles taken offshore SW Taiwan. We observe bottom‐simulating reflector (BSR) that deflects toward the seafloor near thrust faults that indicate localized heat flow variations. At these sites, advecting warm pore fluids transport heat to shallower depths and force the BSR shallower. Our 2D steady‐state numerical method quantifies the fluid flow rates required to cause such thermal anomalies. We found that fluid flow rates near the trench of the accretionary wedge range between 0.1 and 16 m3 yr−1 m−1, with slower and faster rates generally associated with slope basin discontinuities and faults, respectively. To evaluate the fluid pattern evolution from subduction to collision, we studied three transects: one along the Manila subduction zone in the south and two in Taiwan's initial collision zone in the north. We quantified the fluid budget and partitioning of fluid flow between focused discharge through faults and diffusive flow through the wedge. Faults in Taiwan's accretionary wedge capture on average 25% of the total dewatering flux in the younger subduction zone and 38.5% in the tectonically mature collision zone. Our method provides estimates of fluid migration rates along convergent plate boundaries, and contributes to our understanding of focused fluid flow processes in many other regions. Plain Language Summary: Fluids play a key role in many subduction zone processes. However, quantitative constraints on flow expulsion rates and directions are limited. Efficient upward fluid migration through subbottom conduits can be generated tectonically, such as faults. Faults are ubiquitous along convergent margins; yet, a quantitative understanding of their impact on regional fluid budgets, flow rates, and distribution at vent sites remains unclear. We developed a rapid numerical method to constrain 2D focused fluid flow rates using seismically derived thermal structure and applied it to the subduction‐collision zone system off SW Taiwan. To study the influence of long‐term tectonic processes on the fluid budget, we remotely mapped the distribution and amount of focused fluid flow across the convergent margin, using a widespread shallow subbottom temperature field derived from a spatially dense seismic data set covering an area of more than 25,000 km2. We combined the results with other previously published geophysical data sets to calculate the margin fluid budget. We found stronger fluid advection from depth along the collision zone, where thicker sediments are deformed more intensively. Our approach to quantify fluid fluxes is applicable to a range of tectonic regimes and can provide critical insight into local, regional, or even global fluid budget estimates. Key Points: Developed a method to quantify fluid flow rates from BSR‐based temperature dataIdentified fluid partitioning patterns off SW Taiwan from subduction to collisionFocused fault‐related flow controls the local depth of the hydrate stability zone [ABSTRACT FROM AUTHOR]