Search Results (55)

This study investigates the stochastic variation in droplet size generated within a microfluidic flow-focusing cross-junction. A commercial micro cross-junction was used to experimentally analyze droplet formation under fixed flow rate conditions. An in-house machine learning-based algorithm was developed to automatically detect and measure droplet dimensions from high-speed video recordings. Despite constant flow rates, the analysis revealed fluctuations in droplet size, attributed to velocity oscillations induced by syringe pumps. To explore this phenomenon, micro-Particle Image Velocimetry (micro-PIV) was employed to capture velocity profiles, which were then used to define time-dependent boundary conditions for numerical simulations. Simulations were conducted using the OpenFOAM solver interFoam and validated against experimental data. The results demonstrate good agreement and confirm that velocity fluctuations significantly influence droplet formation. This combined experimental and numerical approach provides an innovative, robust framework for understanding and predicting droplet behavior in microfluidic systems. Full article

Background/Objectives: Tubal dysfunction may be a contributing factor in up to 35% of infertility cases, rendering tubal patency assessment a vital component of the infertility workup. In this review we examined the diagnostic efficacy and tolerability of hysterosalpingo-foam sonography (HyFoSy) and compared it to hysterosalpingography (HSG) and hysterosalpingo-contrast sonography (HyCoSy). Methods: Online databases were systematically searched and evaluated according to the PRISMA 2020 guidelines. Statistical heterogeneity was assessed. Diagnostic sensitivity, specificity and inter-method agreement were evaluated, along with mean pain scores. Results: This analysis included data from 9 studies and 1354 patients with conclusive diagnostic data from 2422 tubes and 1294 patients with data on intra-procedural pain. With regard to HyFoSy and HyCoSy comparison, pooled sensitivity was 87% and 69%, respectively (p = 0.074), while pooled specificity was 95% and 85%, respectively, favoring HyFoSy (p < 0.001). HyFoSy was more tolerable with regard to pain, but this was not statistically significant. Regarding the HyFoSy and HSG comparison, pooled Cohen’s k was 0.38, indicating fair-moderate agreement. In subsequent analysis, with HSG as a reference standard, HyFoSy demonstrated low sensitivity (61%) but high specificity (87%). With regard to experienced pain, HyFoSy and HSG had a difference of 2.4 units on a 10-point scale, favoring HyFoSy (p < 0.001). Conclusions: HyFoSy was superior to HyCoSy and may be used as a first-line tubal assessment method, with HSG being utilized in inconclusive cases. However, further research is still required due to the small number of available studies. Full article

In this paper, the geometric effect on flow structure and mixing performance of two miscible fluids (deionized water and glycerol) in a planetary centrifugal mixer (PCM) during the spin-up is numerically evaluated, using the OpenFOAM interMixingFoam solver. Six different aspect ratios, specifically 0.5, 1, 1.25, 1.5, 2, and 2.5, are considered. The flow structure in each geometric configuration is illustrated by the liquid interface and vorticity isosurface represented by the Q criterion, while the mixing performance is evaluated in terms of a mixing index $MI$. As the aspect ratio increases from small to large, $MI$ first increases and then decreases. The peak $MI$ at the end of spin-up reaches 0.196 for the aspect ratio of 1.25, rather than the other five aspect ratios in our study. The mechanism analysis shows that under an aspect ratio of 1.25, the vortex structure is most violently dissipated, the interface collapse degree is the largest, and the low-velocity region volume is the smallest, which enhances the chaotic convection mixing. Full article

Traditional assessments of balance and postural control often face challenges related to accessibility, cost, subjectivity, and inter-rater reliability. With advancements in technology, smartphones equipped with inertial measurement units (IMUs) are emerging as a promising tool for assessing postural control, measuring both static and dynamic motion. This study aimed to develop and validate a novel smartphone application by comparing it with research-grade posturography instruments, including motion capture and force plate systems to establish construct- and criterion-related validity. Twenty-two participants completed the quiet stance under varying visual (eyes open—EO; eyes closed—EC) and surface (Firm vs. Foam) conditions, with data collected from the smartphone, force plate, and motion capture systems. Intraclass correlation coefficients (ICCs) and Pearson correlation coefficients assessed the reliability and validity for all outcome measures (sway area and sway velocity). The results demonstrated reliability, with strong validity between the devices. A repeated-measures ANOVA found no significant differences between the devices. Postural outcomes revealed the significant main effects of both the visual (EO vs. EC) and surface (Firm vs. Foam) conditions. In conclusion, the study demonstrated the validity, sensitivity, and accuracy of the custom-designed smartphone app, offering the potential for bridging the gap between at-home and clinical balance assessments. Full article

The determination of the surface charge density distribution and the transcapacitance of capacitive one-side-access circular sensors with three electrodes on the active surface remains problematic both theoretically and experimentally. To provide an input, a novel experimental study was carried out on the partial permittivity of rigid PU foams by means of a capacitive circular OSA sensor with three electrodes on the active surface. An original and effective method was elaborated in order to determine the model functions of the obtained experimental data of the partial permittivity. A numerical estimation for the rate of change in the partial permittivity was made and the highest rate of change was determined. It was identified that the highest rate of change takes place at the inter-electrode zone and depends on the density and the true permittivity in a nonlinear mode, approximated with second-order polynomials. The overall character of the rate of change in the partial permittivity in the dependence of the radius of the covered area was found to be comparable to that of the surface charge density distribution curve, estimated theoretically for a circular two-electrode OSA sensor. The experimental results on the partial permittivity can be useful in the performance evaluation and design of the optimal proportions of capacitive circular OSA sensors, as well as in the verification of the corresponding mathematical models. Full article

Simulating the free decay motion and wave radiation from a heaving semi-submerged sphere poses significant computational challenges due to its three-dimensional complexity. By leveraging axisymmetry, we reduce the problem to a two-dimensional simulation, significantly decreasing computational demands while maintaining accuracy. In this paper, we exploit axisymmetry to perform a large ensemble of Computational Fluid Dynamics (CFDs) simulations, aiming to evaluate and maximize both accuracy and efficiency, using the Reynolds Averaged Navier–Stokes (RANS) solver interFOAM, in the opensource finite volume CFD software OpenFOAM. Validated against highly accurate experimental data, extensive parametric studies are conducted, previously limited by computational constraints, which facilitate the refinement of simulation setups. More than 50 iterations of the same heaving sphere simulation are performed, informing efficient trade-offs between computational cost and accuracy across various simulation parameters and mesh configurations. Ultimately, by employing axisymmetry, this research contributes to the development of more accurate and efficient numerical modeling in ocean engineering. Full article

The rotating annular flume has been widely adopted to generate quasi-steady and uniform flow, thus serving for the investigation of sediment motion characteristics. This complex flow structure is significantly associated with the rotational speed ratio. The present study aims to explore the optimal speed ratio based on the OpenFOAM simulation. In this paper, the physical properties of a rotating annular flume with different speed ratios are investigated and analyzed in terms of bottom shear stress, turbulent velocity ratio, cross-sectional secondary flow, and vector field by interFoam, a built-in solver of the open-source CFD program OpenFOAM. The RNG k-epsilon model has been adopted to solve multiphase flow problems. The results demonstrate that the optimal speed ratio differs with the specific evaluation criterion. Given the uniform distribution of bottom shear stress, the turbulence velocity ratio, and the minimum secondary flow as the evaluation criteria, the corresponding optimal speed ratios are determined as 1.2, 1.7, and 1.7, respectively. The conclusion is generally consistent with the results derived by other scholars. Computational fluid dynamics programs have been proven as practical tools for investigating complex hydrodynamic characteristics. The present study shares useful insights into the optimal rotational speed ratio of a rotating annular flume. The OpenFOAM-based numerical model will provide guidance for experimental research using rotating annular flumes. Full article

The modeling of floating tidal stream energy turbine (FTSET) systems demands significant computational resources, especially when incorporating fully coupled models that integrate hydrodynamics, mooring, motion response, and their interactions. In this study, a novel hybrid numerical model for FTSET systems has been developed, utilizing the open-source software OpenFOAM. The hydrodynamic characteristics of three-bladed vertical-axis turbines are simulated in steady, three-dimensional wave–current numerical tanks using an unsteady actuator line method (UALM). The interFoam two-phase Navier–Stokes solver within OpenFOAM is utilized to manage the kinematic characteristics of the floating platform. Mooring dynamics are addressed using the mass–spring–damper model (MoorDyn), and turbine wake dynamics are resolved using a buoyancy-modified RANS turbulence model. The comprehensive model can simulate wave, flow, mooring dynamics, platform motion, and the interactions between the turbine and platform within FTSET systems. To validate the model, several scenarios are analyzed, and experiments are conducted to validate the numerical results. The model accurately predicts platform motion responses and mooring line tensions, especially under wave–current conditions, capturing the interconnected effects of platform motion during turbine rotation. Additionally, the model extends predictions of turbine–platform wake development and interaction. Full article

The Columbia River Basin faces a threat from the potential invasion of zebra mussels (Dreissena polymorpha), notorious for their ability to attach to various substrates, including concrete, which is common in fishway construction. Extensive mussel colonization within fishways may affect fish passage by altering flow patterns or creating physical barriers, leading to increased travel times, or potentially preventing passage altogether. Many factors affect mussel habitat suitability including vectors of dispersal, water parameters, and various hydrodynamic quantities, such as water depth, velocity, and turbulence. The objective of this study is to assess the potential for zebra mussels to attach to fishway surfaces and form colonies in the McNary Lock and Dam Oregon-shore fishway and evaluate the potential impact of this infestation on the fishway’s efficiency. A computational fluid dynamics (CFD) model of the McNary Oregon-shore fishway was developed using the open-source code OpenFOAM, with the two-phase solver interFoam. Mesh quality is critical to obtain a reliable solution, so the numerical mesh was refined near the free surface and all solid surfaces to properly capture the complex flow patterns and free surface location. The simulation results for the 6-year average flow rate showed good agreement with the measured water column depth over each weir. Regions susceptible to mussel infestation were identified, and an analysis was performed to determine the mussel’s preference to colonize as a function of the depth-averaged velocity, water depth, and wall shear stress. Habitat suitability criteria were applied to the output of the hydraulic variables from the CFD solution and provided insight into the potential impact on the fishway efficiency. Details on the mesh construction, model setup, and numerical results are presented and discussed. Full article

Foam rolling is widely used in fitness, sports, rehabilitation, and injury prevention. However, there are limited data available on the effect of foam rolling techniques on the upper limbs. The aim of this investigation is to assess the effects of foam rolling the latissimus dorsi area during the rest period between two consecutive lat pull-down exercise (LPDE) sets. Seventeen resistance training experienced volunteer male subjects (25.8 ± 3.4 years; 180.3 ± 9.0 cm; 79.7 ± 9.9 kg) participated in this research. Each subject performed 2 training sessions of LPDE in a random order, separated by one week. Each session consisted of 2 sets of maximum repetitions using 85% of their one-repetition maximum (1RM), with a 7 min rest period between sets. The rest period condition between sets was different in the 2 sessions: passive rest (Pr) or foam rolling the latissimus dorsi muscle bilaterally for 3 sets of 45 s (FRr). The following variables were assessed for each LPDE set: number of repetitions (REPS), average excursion per repetition in millimeters (EXC), average power of the set in watts (AP) and rating of perceived exertion (RPE). Pr did not show any significant change between the first and the second LPDE set for REPS, EXC, and AP. However, there was a significant increase for RPE (8.4 ± 0.5 vs. 8.9 ± 0.5 a.u., p = 0.003) between the two sets. FRr resulted in an increase for REPS (7.1 ± 1.5 vs. 8.2 ± 1.3, p < 0.001) and AP (304.6 ± 61.5 W vs. 318.8 ± 60.8 W, p = 0.034) between the first and the second LPDE sets, but no changes were observed for EXC and RPE. The use of foam rolling techniques on the latissimus dorsi area during the complete rest period between sets in LPDE at 85% 1RM appears to improve the number of repetitions and the movement power without affecting the RPE during the second set. Full article

Highly porous layered double hydroxide (LDH) and its calcined mixed metal oxide (MMO) were obtained by utilizing egg white (EW) as a biogenic porous template. The LDH was prepared through coprecipitation under the existence of a beaten EW meringue, and the corresponding MMO was obtained by calcining LDH at 500 °C. According to X-ray diffraction, the crystal structure of LDH and MMO was well-developed with or without EW. In contrast, the crystallinity analyses and microscopic investigations clearly showed differences in the particle orientation in the presence of EW; the protein arrangement in the EW foam induced the ordered orientation of LDH platelets along proteins, resulting in well-developed inter-particle pores. As a result, the distinctive particle arrangement in EW-templated samples compared with non-templated ones showed dramatically enhanced specific surface area and porosity. The nitrogen adsorption–desorption isotherm exhibited that the high specific surface area was attributed to the homogeneous nanopores in EW-templated LDH and MMO, which originated from the sacrificial role of the EW. Full article

Textile dyes widely used in industrial products are known as a major threat to human health and water ecological security. On the other hand, sol gel represents a principal driver of the adoption of dispersive solid-phase microextractors (d-µ SPME) for pollutants residues in water. Thus, the current study reports a new and highly rapid and highly efficient hybrid sol-gel-based sponge polyurethane foam as a dispersive solid-phase microextractor (d-µ-SPME) platform packed mini-column for complete preconcentration and subsequent spectrophotometric detection of eosin Y textile dye in wastewater. The unique porous structure of the prepared sol-gel immobilized polyurethane foams (sol-gel/PUF) has suggested its use for the complete removal of eosin Y dye (EY) from water. In the mini-column, the number (N) of plates, the height equivalent to the theoretical plates (HETP), the critical capacity (CC), and the breakthrough capacities (BC) of the hybrid sol-gel-treated polyurethane foams towards EY dye were determined via the breakthrough capacity curve at various flow rates. Under the optimum condition using the matrix match strategy, the linear range of 0.01–5 µg L⁻¹, LODs and LOQs in the range of 0.006 µg L⁻¹, and 0.01 µg L⁻¹ for wastewater were achieved. The intra-day and inter-day precisions were evaluated at two different concentration levels (0.05 and 5 μg L⁻¹ of dye) on the same day and five distinct days, respectively. The analytical utility of the absorbents packed in pulses and mini-columns to extract and recover EY dye was attained by 98.94%. The column could efficiently remove different dyes from real industrial effluents, and hence the sol-gel/PUF is a good competitor for commercial applications. The findings of this research work have strong potential in the future to be used in selecting the most suitable lightweight growing medium for a green roof based on stakeholder requirements. Therefore, this study has provided a convenient pathway for the preparation of compressible and reusable sponge materials from renewable biomass for efficient removal of EY from the water environment. Full article

The interaction between solitary waves and underwater barriers is investigated using our in-house code, entitled VPM (volume-average/point-value multi-moment)–THINC/QQ (THINC method with quadratic surface representation and Gaussian quadrature)-coupled model. The stability and accuracy of the proposed model are validated by comparing the numerical results with those of the well established two-phase flow solver interFoam. All the results indicate that the presented coupled model has the advantage of high fidelity in simulating solitary wave propagation. Subsequently, solitary waves passing over a single underwater barrier are simulated by the present model. Numerical results are compared with experimental results in terms of the free surface elevation, velocity profile, vorticity field, and wave forces. Great agreements are obtained. In the end, the interactions between solitary waves and double underwater barriers are investigated numerically. The results reveal that the reflection coefficient increases first, and then decreases, with the increasing space between the two barriers. For cases with different wave heights, the transmission coefficient decreases monotonically, and the dissipation coefficient is opposed to the transmission coefficient. Full article

A solution casting approach is used to create hollow glass microsphere (HGM)-filled epoxy–syntactic foam composites (e–SFCs) by varying the concentrations of HGM in epoxy according to different particle sizes. Density analysis is used to investigate the impact of concentration and particle size regularity on the microstructure of e-SFCs. It was observed that e–SFCs filled with an HGM of uniform particle sizes exhibit a reduction in density with increasing HGM concentration, whereas e-SFCs filled with heterogeneous sizes of HGM exhibit closeness in density values regardless of HGM concentration. The variation in e–SFC density can be related to HGM packing efficiency within e–SFCs in terms of concentration and particle size regularity. The particle size with lowest true density of 0.5529 g/cm³, experimental density of 0.949 g/cm³ and tensile strength of 55.74 MPa resulted in e-SFCs with highest specific properties of 100.81 (MPa·g/cm³), with a 35.1% increase from the lowest value of 74.64 (MPa·g/cm³) at a true density of 0.7286 g/cm³, experimental density of 0.928 g/cm³ and tensile strength of 54.38 MPa. The e–SFCs’ theoretical density values were obtained. The variance in theoretical and experimental density values provides a thorough grasp of packing efficiency and inter-particle features. Full article

This study focuses on the numerical investigation of the 3D hydrodynamic processes of coastal zones such as wave breaking, wave-induced currents, and sediment transport, using the multiphase, interFoam solver of OpenFOAM^® (a state-of-the-art, open-source CFD numerical tool). The numerical scheme is suitably framed by initial conditions of wave propagation and absorption using waves2Foam wave library. The turbulence closure problem is handled using a buoyancy modified k–ω SST model. In order to predict the sediment transport rate due to waves and currents (bed load, sheet flow, and suspended load over ripples), a transport-rate formula involving unsteady aspects of the sand transport phenomenon is implemented. For the suspended load in the surf zone, the Bailard formula is adopted after considering that the dissipation mechanism is the wave breaking. Results concerning wave height, longshore current, turbulence kinetic energy, and sediment transport are compared against experimental data and semi-empirical expressions. Full article