Immersion Depth Research Articles

A Numerical Study on the Bragg Resonance Characteristics of Multiple Floating Breakwaters

This study investigates the Bragg resonance characteristics of multiple independently moored floating breakwaters and their wave attenuation performance using a computational fluid dynamics (CFD) model, OpenFOAM. The numerical framework is validated against experimental data for wave generation and floating body motion responses, demonstrating its reliable accuracy. Results show that Bragg resonance occurs in floating breakwater arrays, with the reflection coefficient peaking when the ratio of spacing to half-wavelength is an integer. Deeper immersion depth and longer boxes can enhance both Bragg reflection and energy dissipation by intensifying vorticity around the structures. Increasing the number of floating boxes marginally affects Bragg reflection but notably improves wave energy dissipation, primarily due to additional pontoons generating more turbulent motion. The optimal wave attenuation condition does not fully coincide with the peak Bragg reflection, highlighting the combined effect of reflection and dissipation of movable floating breakwaters. Future studies may further focus on the irregular wave conditions and impacts of the mooring system on the Bragg reflection and wave energy dissipation effect of multiple floating breakwaters.

Designing Audience Flow State in Narrative Media

Narrative media emerges its flow state model from a relationship between audience relatability and narrative continuity. When viewers engage with a story, their cognitive abilities and emotional investment interact with the coherence of the narrative, which determines the depth of immersion. Existing research highlights that textual cohesion, probabilistic continuity, and emotional transitions are key to sustaining flow when receiving stories through media. However, cultural background and audience familiarity with storytelling conventions also influence the interpretation of story content and, therefore, cause different degrees of immersive experiences. This study proposes a Two-Dimensional Flow Framework, categorizing factors for flow state into relatability—how much the viewer identifies with the story—and continuity—the logical progression of the narrative. Misalignment in these dimensions can lead to disengagement through negative emotions. This framework allows creators to craft narratives that sustain audience engagement without overwhelming or under-stimulating them through curating the relationship between audience relatability and narrative continuity. The findings suggest that cognitive compatibility and emotional resonance deepen audience connection and sustained participation, so future storytellers should consider these factors when designing narrative media.

Nonlinear resonant vibration of a partially immersed beam in viscous fluid.

This article presents an experimental exploration of the nonlinear vibration of a partially immersed cantilever beam. A set of hypotheses was developed to study the influence of the geometry (immersion depth and volume of the fluid) and fluid properties (viscosity and density) on the nonlinear response of the beam, and a test matrix of combinations of different parameters was generated. From the nonlinear experiments, linear parameters such as resonant frequency, damping ratio, and nonlinear parameters such as nonlinear frequency shift and nonlinear damping ratio were extracted. Finally, a regression analysis was carried out to determine the statistical relationships between different parameters, and the linear parameters were compared against results reported in the literature. The results suggest that the volume of the fluid has no dependence on the vibrational response, and a coupling between immersion depth, viscosity, and density was observed.

Elevated push-plate wave maker in experimental water tank

Elevated wave maker enables wave making under different water depths. In this study, a wave-making theory of EPP (elevated push-plate) wave maker is established, and the scheme in large experimental water tank is introduced. The transfer functions and functional curves are analyzed. The EPP wave maker is experimentally verified, and the performance in water tank is investigated and reported. Finally, the wave-making capability, stability, repeatability, and consistency of the EPP wave maker are explored. The main results are summarized as follows: (1) The theory of the EPP wave maker matches well with the experimental results, and the error is less than 5%; it is indicating that the theory of the EPP wave maker is reasonable and can guide the working of the EPP wave maker. (2) The transfer function of the EPP wave maker is mainly related to the immersion depth and has little relationship with the water depth. (3) The wave height can reach 0.479 m under 3 m water depth, and the corresponding period is 1.82 s. The wave height can reach 0.484 m under 2 m water depth, and the corresponding period is 2.50 s. All tested results fall on the envelope of the functional curve.

Design of a droplet water wave concentrator

A droplet concentrator for water wave consisting of multiple droplet-shaped cylindrical bodies is designed, based on the scattering cancelation method. A numerical model of wave–concentrator interaction is established using the commercial software Star-CCM+. The simulation results have proved that the amplification factor of the wave amplitude by this droplet concentrator is at most 5.09. From the analysis of the vortex field, the droplet-shaped structure exhibits superior hydrodynamic performance. From the perspective of coordinate transformation theory, the droplet-shaped wave concentrator has a higher coordinate transformation ratio. Therefore, the proposed droplet-shaped concentrator demonstrates enhanced performance. Furthermore, the effects of incident wave frequency, wave height, and the immersion depth of the concentrator on the performance are investigated. This study provides a valuable blueprint for the practical application of wave concentrators, which may have significant potential in wave energy extraction, thereby promoting the commercialization of wave energy.

Model representation of the influence of hydraulic mixture backwater in the washout chamber on the hydraulic elevator lifting height

Purpose. To investigate the influence of hydraulic mixture backwater in the washout chamber on the lifting height of the hydraulic elevator and determine optimal operating parameters under significant submersion conditions. Methodology. Experimental studies were conducted using hydraulic elevators with nozzles of 15, 20 and 25 mm diameters. The effects of working agent pressure, nozzle diameter, and jet immersion depth on productivity, energy intensity, and specific water consumption were evaluated. The experimental results were approximated using empirical dependencies and graphical analysis. The experimental results were approximated using empirical dependencies and graphical analysis to establish functional relationships between the system parameters. Findings. It was found that the jet immersion depth under the rock layer significantly affects the hydraulic elevator’s performance. Experiments with nozzles of different diameters showed that for each diameter, there is a water pressure limit beyond which no significant increase in the delivery distance of the hydraulic mixture occurs. For nozzles with diameters of 15, 20 and 25 mm, the water pressure limits were 1.5, 2.0 and 2.5 MPa, respectively. Increasing the pressure and nozzle diameter improves the efficiency of rock washout and delivery distance but is accompanied by an increase in process energy intensity. Originality. For the first time, dependencies of the hydraulic elevator’s productivity on jet immersion depth and working agent pressure for various nozzle diameters were established. Empirical models were developed to predict the efficiency of hydraulic mixture lifting under variable submersion conditions. Practical value. The research results can be used to optimize the design and operation of hydraulic elevators under significant hydraulic mixture backwater conditions. A hydraulic elevator with the following parameters is recommended for lifting the hydraulic mixture to the surface: nozzle diameter – 25 mm, mixing chamber diameter and length – 70 and 150 mm, respectively; hydraulic elevator module – 8 mm; pulp collecting column diameter – 100 mm.

Nonlinear vibration analysis of a generally orthotropic cracked micro-plate with variable thickness considering fiber effects and fluid-structure interaction

This research investigates the nonlinear vibration response of partially cracked, generally orthotropic, rectangular micro-plates featuring non-uniform thicknesses coupled with a fluid medium. The traditional classical plate theory (CPT) in conjunction with a modified couple stress theory (MCST) is used to derive the governing equation of a generally orthotropic rectangular plate of varying thickness. The presence of a partial crack at the plate’s center is modeled using a simplified line spring model (LSM), and in-plane forces and bending moment resulting from a partial crack are incorporated into the equation. Furthermore, the interaction with a fluid medium is considered, with the introduction of virtual added mass via the velocity potential function and Bernoulli’s equations, considering both horizontal and vertical plate immersion scenarios. The study also explores thickness variations in one and two dimensions along the X and Y axes. The methodology employs Galerkin’s approach to convert governing equations into time-dependent modal coordinates, and Berger’s method introduces nonlinearity into these coordinates. The approximation solution, a method of multiple scales, is utilised to solve the plate’s nonlinear governing equations. Various parameters are considered in the analysis, including crack length, size effect, thickness variations, fiber orientations, fluid levels, and immersion depth. The study explores the impact of these factors on the vibration behaviour of submerged partially cracked, generally, orthotropic non-uniform thickness micro-plates under two different boundary conditions, presenting novel findings. Additionally, an illustration is provided to visually depict the bending-hardening and bending-softening phenomenon concerning the taper constant and depth of submergence.

Insight into the Common W-Shaped Uneven Solidification Profile in Slab Casting: From Mechanisms to Targeted Strategies.

This study elucidates the underlying formation mechanisms and mitigation strategies for the W-shaped solidification profile in slab continuous casting. Through the development of a multiphysics coupling numerical model, integrated with measured nozzle cooling characteristics in the secondary cooling zone, the effect of steel flow patterns in mold and non-uniform cooling conditions in the secondary cooling zone on solidifying shell evolution is systematically studied. A principal finding is that wide-face shell erosion, induced by both the radial expansion jet and the lower recirculation, constitutes the primary determinant of uneven shell thickness. An increase in the immersion depth and inclination angle of the nozzle side-hole exacerbates the non-uniformity of the solidified shell. Non-uniform cooling in the secondary cooling zone further amplifies the shell thickness differences, culminating in characteristic dumbbell-shaped solidified shell geometry. Strategic implementation of localized enhanced cooling on the wide face in the secondary cooling zone demonstrates significant improvement in shell uniformity, with implementation efficacy contingent upon a critical process window (Segments 1-6). These findings establish mechanistic foundations and deliver practical guidance for minimizing centerline segregation through optimized continuous casting parameter configuration.

Finding Peace in Pixels: Exploring the Therapeutic Mechanisms of Virtual Nature for Young Adults' Mental Well-Being.

Background: This investigation examines the phenomenological dimensions of young adults' engagement with virtual natural environments for psychological stress amelioration through rigorous thematic analysis. Contemporary epidemiological data reveal a concerning prevalence of stress among young adults aged 18 to 29 years, with approximately 30% reporting moderate to severe manifestations. Despite virtual reality (VR)'s emergence as a promising modality for mental well-being interventions, a significant lacuna exists regarding the qualitative understanding of these immersive experiences. Methods: Through semi-structured interviews with 35 young adults following a four-week VR nature intervention, we constructed a conceptual framework comprising five interconnected strata: intervention, experience, process, context, and outcome. Results: Our analysis illuminated intricate bidirectional relationships among sensory elements, emotional responses, immersion depth, interactive affordances, post-session effects, psychological development, implementation challenges, individual variability, and comparative efficacy. The findings demonstrate congruence with both Attention Restoration Theory and Stress Recovery Theory while necessitating consideration of technology-specific mediators. Notably, the identified "stress barrier" phenomenon temporarily inhibited intrusive cognitions, suggesting promising therapeutic mechanisms. Pronounced heterogeneity in environmental preferences and psychophysiological responsiveness underscores the imperative for personalized implementation strategies. Conclusions: These insights provide substantive guidance for VR nature applications across therapeutic, occupational, and educational domains, potentially augmenting our repertoire for addressing stress-related sequelae in contemporary society.

Phase downshift phenomenon in Bragg reflection of water waves by periodic dual-wing floating breakwaters

Abstract The study develops a numerical model based on the Boundary Element Method (BEM) to analyze Bragg reflection resulting from the interaction of surface gravity waves with a finite array of rigid dual-wing floating breakwaters (DWFBs) using small-amplitude water wave theory. The DWFBs are designed in three distinct shapes-concave, inclined, and convex-to enhance the efficiency of wave damping. The accuracy of the numerical results is validated by comparing Bragg reflection, reflection coefficients, and transmission coefficients with known results for floating box-type structures available in the literature. The findings indicate that Bragg reflection occurs consistently near 2D/λ ≈ 1.0 (D the distance between the centers of any two successive DWFBs and λ the wavelength of the incident wave.), regardless of the breakwater’s shape. The proposed solution effectively determines the reflection coefficient and characterizes the phase-downshift behavior associated with Bragg resonance. Additionally, the study investigates wave interactions with multiple DWFBs, revealing the mechanisms driving phase-downshift behavior. It highlights the influence of factors such as breakwater length, immersion depth, and the number of DWFBs on Bragg reflection, offering insights into optimizing breakwater design for enhanced wave attenuation.

A theoretical and experimental study on optimal immersion method for microsphere-assisted microscopic imaging

Abstract With assistance of a microsphere immersed into a liquid medium, imaging resolution of microscope can exceed the Abbe diffraction limit, making the technique promising for super-resolution microscopic imaging. To achieve optimum assistance to the microscopic imaging, we have studied the microsphere immersion method in both theory and experiment. The impact of liquid immersion depth on the super-resolution imaging quality has been theoretically studied at first in both viewpoints of photonic nanojet and angular spectrum theory of backward propagation of waves. The results show that intensity, full width at half maximum and focal length of the focusing beam/spot are optimal at the semi-immersion state, resulting in considerable promotion of imaging contrast, resolution and magnification. To verify the theoretical results, experiments have been done in case that 10 μm-diameter SiO2 microspheres were semi-immersed into ethanol liquid. The results show that the semi-immersed SiO2 microspheres can assist, in the largest extent, the imaging with a contrast improved by 73.3% and a magnification increased by a fold of 1.9. In comparison with previous preliminary experimental study on super-resolution imaging of immersed microspheres, present paper performs a study in both theory and experiment, and proves that the semi-immersion state is optimum.

Hydrodynamic evaluation and parametric analysis of stern flap impact on performance for high-speed displacement vessels with transom stern

ABSTRACT This study examines the hydrodynamic impact and energy efficiency benefits of stern flap installations on high-speed displacement vessels with transom sterns. Using towing tank experiments and CFD simulations, the research evaluates how different stern flap parameters influence resistance and power consumption. Results show a consistent reduction in resistance and power demands, particularly at Froude numbers above 0.2. For vessels operating in the 0.3–0.4 Froude number range, power savings of up to 6% were observed. The study emphasizes the importance of optimising flap design based on operational conditions, with smaller flaps being more effective at lower speeds. Additionally, transom immersion depth was identified as a critical factor in efficiency. The strong correlation between experimental and CFD results validates the benefits of stern flaps in improving vessel performance and reducing environmental impact, highlighting their potential for enhancing energy-efficient ship designs.

Effects of Adding Facial Immersion to Chest-Level Water Immersion on Vagally-Mediated Heart Rate Variability.

Recent studies have shown that both facial immersion and head-out water immersion up to the chest (HOIC) positively influence cardiac vagal activity, as indexed non-invasively through vagally mediated heart rate variability (vmHRV). While facial immersion activates the diving reflex, HOIC induces effects via hydrostatic pressure, each engaging distinct physiological mechanisms. This study aims to investigate whether combining facial immersion with HOIC results in an additional increase in vmHRV. In total, the vmHRV [log10RMSSD] of 37 participants (14 females, Mage = 23.8; SDage = 4.4 years) was assessed under two conditions, with resting and recovery measurements taken before and after each condition. The first condition involved HOIC alone (M = 1.97, SD = 0.27), followed by HOIC combined with facial immersion (M = 1.87, SD = 0.29). HOIC alone significantly increased RMSSD compared to baseline (p < 0.001); however, no additional increase was observed when facial immersion was added (p = 0.436). This suggests that, while HOIC effectively increases vmHRV, the addition of facial immersion does not provide any further enhancement under the conditions tested. Potential methodological limitations, such as the absence of breath holding, variability in immersion depth, and the use of thermoneutral water temperatures, may have influenced the outcomes and warrant further investigation.

Hydrocarbon Fuel Burning Analysis Using a Variable B-Number on Turbulent Water Surface with Immersed Thermal Conductors

ABSTRACT This study investigates the combustion mechanisms of a floating hydrocarbon fuel layer with immersed heat conductors on a turbulent water surface. A mass burning rate model is developed using a variable B-number that accounts for heat transfer pathways and the modified latent heat of gasification, which improves the characterization of the B-number for the accuracy of burning rate prediction. Experiments are conducted in a bench-scale turbulent water tank, revealing significant relationships between combustion behavior and parameters such as fuel type, fuel layer thickness, turbulence intensity, and conductor immersion depth. Quantitative analyses are performed on the convective and radiative heating of the flame, the conductive and radiative feedback from the rod, radiative losses from the burning pool surface, and the heat losses at the fuel/water interface. The modified heat of vaporization for heptane ranges from 346.7–488.4 kJ/kg, compared to 974.7–1257.3 kJ/kg for dodecane. The heat transfer from the rod to the fuel layer is sensitive to turbulence intensity, showing a 26% and 38% reduction with rod immersion as u′ increases from 1.7 to 3.3 cm/s. The mass burning model has R 2 equal to 82.5%. A parametric study further evaluates the burning enhancement effects of immersed rods.

Expansion Characteristics and Shear Behavior of Reinforced Concrete Beams Under Non-Uniform Expansion Induced by Alkali-Silica Reaction.

Alkali-silica reaction (ASR) is an important factor that seriously affects the durability of reinforced concrete (RC) structures. The current research on alkali-aggregate mainly focuses on the deterioration mechanism of materials and the mechanical properties of standard specimens. However, there is a gap in the field of research on the effect of alkali-aggregate damage on the level of RC structures. In this study, five RC beams were tested, and the depth and location of alkali solution immersion were used as the test variables, with the aim of investigating how the steel reinforcement suppresses the expansion caused by ASR and evaluating the shear behavior of RC beams after non-uniform ASR damage. The results of the study showed that immersion in an alkali solution and an increase in immersion depth accelerated the rate of expansion development, while steel reinforcement inhibited the rate of expansion development. Compared with undamaged RC beams, ASR initially generates expansion stresses within the concrete, which increase the cracking and yield loads of RC beams and delay the cracking of RC beams, and ASR reduces the ultimate load-carrying capacity and ductility of RC beams due to the disruption of the concrete microstructure. Finally, a chemo-mechanical analysis method is proposed based on experimental results, which incorporate an ASR expansion model and a pore mechanics model. The efficacy and precision of this model are validated through comparison with experimental results.

A Flexible Rolling Triboelectric Nanogenerator with a Bionic Gill Cover Structure for Low-Velocity Water Flow Energy Harvesting.

Harvesting low-velocity water flow energy stably over the long term is a significant challenge. Herein, a flexible rolling triboelectric nanogenerator with a bionic gill cover structure (GFR-TENG) to harvest steady low-velocity water flow energy is proposed. The dielectric material of the GFR-TENG is eight flexible hollow fluorinated ethylene propylene (FEP) pipes, which guarantees that rolling friction is formed between the dielectric material and copper electrode. This design significantly reduces wear between the dielectric material and copper electrode and enhances the durability of the triboelectric nanogenerator. Even after 1700000 cycles, its performance retention rate is more than 95%. The GFR-TENG using the wheel with bionic whale shark gill cover structure exhibits outstanding hydrodynamic performance, increasing by 24.54% comparing the normal wheel on the rotation frequency. In the research of water parameters, the GFR-TENG can steadily harvest water flow energy at a low-velocity water flow of 0.22ms-1. Meanwhile, the GFR-TENG can all exhibit outstanding performance at different immersion depths. Finally, a wireless temperature sensor and a wireless light sensor are each powered by the GFR-TENG, which harvests energy from water flow in a natural open channel. The GFR-TENG provides a novel solution method for harvesting low-velocity water flow energy.

Numerical study of the influence of hydrofoil hydrodynamic performance considering near-free surface

Bionic flapping hydrofoil motion is increasingly used in bionic underwater robots. However, many scholars have focused their attention on the navigation problem in deep-water environments, thus ignoring changes in the hydrodynamics of hydrofoils under the action of the near-free-surface effect. This paper studies and explores the hydrofoil motion in near-free surfaces through the RANS viscous flow numerical simulation method, combined with overset mesh and adaptive mesh technology. Three different forms of motion are studied respectively, including a stationary fixed, a single-degree-of-freedom pitch and a two-degree-of-freedom heaving-pitching coupled hydrofoil. The effects of varying the immersion depth d on the lift and thrust generated were analyzed. Results indicate noticeable differences in the free surface action among different motion forms. When the water depth is less than one chord length C, the lift and thrust of the three motion forms decreased rapidly decrease. When d/C=1~1.5, the static fixed hydrofoil lift and thrust gradually approach the deep-water state. When d/C&gt;2, the pitching motion of a single degree of freedom also tends to be stable. The two-degree-of-freedom motion is d/C&gt;3. This finding shows that the effect of the near-free surface is closely related to the vertical motion. The greater the vertical motion is, the more severe the effect.

Study of immersion of deep softeners of a combined machine for agricultural applications in vineyards: Ensuring consistent depth and uniform movement

This article presents theoretical and experimental research on the performance of deep softeners in a combined machine designed for agricultural applications, particularly in vineyards. The study focuses on achieving consistent working depth and stable operation between rows of grapevines. Theoretical analysis highlights the importance of accurately determining the vertical distance from the support plane to the lower suspension points to ensure the desired immersion depth and operational stability. To verify the theoretical findings, experiments were conducted to evaluate how the depth of cultivation and the root mean square deviation of the vertical distance influence tensile strength during operation. The tests involved adjusting the vertical distance from the base plane to the lower suspension points incrementally from 65 cm to 80 cm, with fixed vertical spacing of 90 cm between upper and lower suspension points. A cultivation depth of 45 cm was maintained, and the machine operated at speeds of 6 and 8 km/h. Results showed that the optimal vertical distance from the support plane to the lower suspension points should be at least 75 cm to ensure efficient and consistent operation of the deep softeners in vineyard conditions.

Development of a gearbox test rig to evaluate the impact of oil formulations on churning and friction losses

From large industrial to small high-speed transmission for electric vehicles, there is a growing interest in reducing the power losses on gearboxes. Hydrodynamic losses are especially relevant on high-speed gearboxes. On electric cars, the gearbox lubricant also works as a cooling fluid for the motor, which brings new challenges as performance under an electrified environment, thermal and electrical conductivity, corrosion protection etc. Most current test rigs use the torque difference between gearbox output and input to calculate the power losses. This work, uses the instantaneous deceleration on a small gearbox to obtain the no-load depending on power losses. Due to its simplicity, the proposed method has the potential to be applied to actual transmissions with very simple sensors and without the need for significant intervention on the actual equipment. The experimental results showed increased churning power losses with the immersion depth and oil viscosity. With the tested transmission oils, the churning losses showed to depend on rotational speed by a power of three, as predicted by the ISO model. The influence of oil viscosity was less evident. Reducing viscosity 2.5 times showed only around 25% reduction in the calculated churning losses. In opposition to the tested transmission oils, a low-viscosity oil with Friction Modifier additives reduced the power losses with the consecutive larger volumes of sump oil, such unexpected result can be explained by the beneficial effect of the oil FM additives.

The Molecular Mechanism of Fluorescence Lifetime of Fluorescent Probes in Cell Membranes.

Fluorescence probes play crucial roles in unraveling the structure and dynamics of cell membranes including membrane fluidity, polarity, and lipid molecule ordering. The fluorescence lifetime of probes describes the average duration of time that a fluorescent molecule remains in an excited state before returning to the ground state, which is sensitive to environmental changes. However, the molecular mechanism and inherent properties to determine the fluorescence lifetimes remain unexplored and inadequately studied. Furthermore, the effects of the probe on the membrane are also unclear. In this study, we investigated the interactions between probes and lipids, as well as the structural properties of probes within the outer and inner membrane of Mycobacterium smegmatis (Msm) by combining molecular dynamics (MD) simulations, enhanced sampling methods, fluorescence lifetime imaging microscopy (FLIM), and time-correlated single photon counting (TCSPC). The results show that even though the probes have very little effect on the membrane lipids, different membrane environments significantly affect the fluorescence lifetime of the probes. The analysis based on the all-atom simulations shows a strong correlation between the probe's immersion depth within the membrane and its fluorescence lifetime. Specifically, probes buried in the membrane environment shielded from rapid water molecule collisions exhibit longer fluorescence lifetimes. The molecular basis of the fluorescence lifetime of probes in cell membranes revealed in this work would enhance the comprehension of fluorescence probes and facilitate the rational design of novel efficient probes.