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Ecological and evolutionary theories have proposed that species traits should be important in mediating species responses to contemporary climate change; yet, empirical evidence has so far provided mixed evidence for the role of behavioral, life history, or ecological characteristics in facilitating or hindering species range shifts. As such, the utility of trait-based approaches to predict species redistribution under climate change has been called into question. We develop the perspective, supported by evidence, that trait variation, if used carefully can have high potential utility, but that past analyses have in many cases failed to identify an explanatory value for traits by not fully embracing the complexity of species range shifts. First, we discuss the relevant theory linking species traits to range shift processes at the leading (expansion) and trailing (contraction) edges of species distributions and highlight the need to clarify the mechanistic basis of trait-based approaches. Second, we provide a brief overview of range shift-trait studies and identify new opportunities for trait integration that consider range-specific processes and intraspecific variability. Third, we explore the circumstances under which environmental and biotic context dependencies are likely to affect our ability to identify the contribution of species traits to range shift processes. Finally, we propose that revealing the role of traits in shaping species redistribution may likely require accounting for methodological variation arising from the range shift estimation process as well as addressing existing functional, geographical, and phylogenetic biases. We provide a series of considerations for more effectively integrating traits as well as extrinsic and methodological factors into species redistribution research. Together, these analytical approaches promise stronger mechanistic and predictive understanding that can help society mitigate and adapt to the effects of climate change on biodiversity.

With ongoing global warming, increasing water deficits promote physiological stress on forest ecosystems with negative impacts on tree growth, vitality, and survival. How individual tree species will react to increased drought stress is therefore a key research question to address for carbon accounting and the development of climate change mitigation strategies. Recent tree‐ring studies have shown that trees at higher latitudes will benefit from warmer temperatures, yet this is likely highly species‐dependent and less well‐known for more temperate tree species. Using a unique pan‐European tree‐ring network of 26,430 European beech (Fagus sylvatica L.) trees from 2118 sites, we applied a linear mixed‐effects modeling framework to (i) explain variation in climate‐dependent growth and (ii) project growth for the near future (2021–2050) across the entire distribution of beech. We modeled the spatial pattern of radial growth responses to annually varying climate as a function of mean climate conditions (mean annual temperature, mean annual climatic water balance, and continentality). Over the calibration period (1952–2011), the model yielded high regional explanatory power (R2 = 0.38–0.72). Considering a moderate climate change scenario (CMIP6 SSP2‐4.5), beech growth is projected to decrease in the future across most of its distribution range. In particular, projected growth decreases by 12%–18% (interquartile range) in northwestern Central Europe and by 11%–21% in the Mediterranean region. In contrast, climate‐driven growth increases are limited to around 13% of the current occurrence, where the historical mean annual temperature was below ~6°C. More specifically, the model predicts a 3%–24% growth increase in the high‐elevation clusters of the Alps and Carpathian Arc. Notably, we find little potential for future growth increases (−10 to +2%) at the poleward leading edge in southern Scandinavia. Because in this region beech growth is found to be primarily water‐limited, a northward shift in its distributional range will be constrained by water availability. [ABSTRACT FROM AUTHOR]

This is a case report that explores the intact selfobject tie and how it supports and promotes the leading edge of self-development in Intersubjective Self Psychology. This discussion is divided into three sections: the first four years of therapy, the middle years, and the final two plus years of a thirteen-year treatment. In the initial years of the treatment, the sustained intact selfobject tie unfolds in the therapeutic relationship, allowing for the expression of the leading edge strivings of both participants, which dominates the intersubjective field. This segment of the treatment has multiple focal points: how to promote and sustain the intact selfobject tie, the leading edge and curative agent of an ISP-informed treatment and how and why transference-based interpretations of the selfobject relationship actively contribute to a successful treatment by broadening and deepening the therapeutic collaboration. The “we” of the relationship is examined, including how an active discussion of the “we” strengthened the bond between them and how this shorthand, which felt generative to the patient and therapist, resulted in the solidification of the leading edge. The middle years of the treatment documents some examples of how the leading edge is manifested in the patient developing a sense of agency and a growing sense of self. In the last year and a half of the therapy, the depth of the leading edge is explored as both the patient and analyst encounter an unexpected turn in the patient’s physical health. This complicated the nature of how the leading edge was expressed. Over a long history of exploring and knowing each other, the “we” between them made possible an extraordinary leading edge experience for both. [ABSTRACT FROM AUTHOR]

In this paper, I provide a synopsis of the core concepts of Intersubjective Self Psychology or ISP, and seek to demonstrate how ISP, with its focus on the leading edge, represents a new paradigm for clinical practice. I want to highlight the difference the ISP perspective makes on how we think about the therapeutic process and therefore, how we work. My introduction to the theory will provide the reader with the theoretical foundation for how to listen to the clinical presentations that my colleagues, Aviva Rohde and Harry Paul, will present in the two subsequent papers. [ABSTRACT FROM AUTHOR]

Context: Once common, the northern long-eared bat (Myotis septentrionalis) has experienced declines > 90% due to white-nose syndrome (WNS). This severe mortality has resulted in their listing under the Endangered Species Act and made them a conservation priority. However, their broad distribution, variability in habitat use, and population instability make developing range-wide conservation strategies difficult. To understand how conservation of M. septentrionalis may vary across its range, we examined shifts in M. septentrionalis site occupancy on the edge of their historic range following severe WNS mortality. Objectives: Our goal was to determine how mortality from white-nose syndrome affects site occupancy of M. septentrionalis at the southern edge of their historic range. Understanding which areas will remain occupied during disease related mortality will help inform management during disease outbreaks. Methods: We used 11 years (2007–2017) of mist-netting records to construct dynamic occupancy models of M. septentrionalis in northern Georgia, USA. Occupancy was updated annually, with the initial period defined as all years prior to the winter of 2012–2013, which corresponds to when white-nose syndrome entered the study area. We assessed occupancy using landscape metrics at the home range (65 ha) and landscape (491 ha) scales, year since WNS occurrence in the study area, distance to karst, and distance to nearest WNS positive county. We estimated probability of detection using Julian date and sampling effort. Results: Initial site occupancy was positively associated with percent deciduous forest cover at the home range scale. As M. septentrionalis populations declined from WNS, a site becoming unoccupied was negatively correlated with mean contiguity of forest at the home range scale and largest patch of forest and mean elevation at the landscape scale. Site occupancy declined precipitously in the years following WNS, dropping from 70.75% (41.76–96.98% [95% CI]) occupancy pre-WNS to 0.3% (0.3–20.5% [95% CI]) by the final year of the study. Conclusions: Our results demonstrated that sites occupied by M. septentrionalis closer to the historic range edge were more vulnerable to becoming unoccupied after disease arrival. We recommend managers on the periphery of the historic range focus conservation efforts on high elevation forested areas nearer to the range core. [ABSTRACT FROM AUTHOR]

Aim: Despite warming temperatures, some species are found persisting at the trailing edge of their distribution. Microclimates provided by complex topography are considered a key factor in these cases of range stationarity, buffering stress from exposure to warming and enabling persistence. However, for species with trailing‐edges located in human‐modified landscapes, refugial conditions provided by microclimates could be disrupted by human activities. Here, we aimed to understand the determinants of trailing‐edge occupancy for a small lagomorph found in rocky patches harbouring cool microclimates. Location: Hokkaido Island, Japan. Taxon: Northern pika (Ochotona hyperborea). Methods: We surveyed the occupancy of northern pikas across a wide elevational gradient (350–2200 m) for two consecutive summers. Ambient air and microhabitat (i.e. rock interstices) thermal conditions were measured to assess their relationship. We then analysed their effects on occupancy at two nested spatial scales: (1) whole‐distribution, and (2) at identified trailing‐edge sites where we explored the effects of microclimates and surrounding human activities (i.e. distance to nearest road and area of human land use such as plantation forests or agricultural fields). Results: Overall, rock interstices exhibited cooler conditions than ambient air with temperature differences of 1–2°C. The overall distribution of northern pikas was affected by both mean ambient temperature and microhabitat availability, with warmer (lower elevation) sites with less microhabitats corresponding to the trailing edge of its distribution. Interestingly, trailing edge occupancy patterns were best explained by the negative effect of surrounding human land despite the existence of suitable microclimates in the rocky patches. Main Conclusions: Our findings suggest that the local refugial conditions supported by cool microclimates are likely to be disrupted by the effects of human land alterations at the larger landscape scale. This result highlights the importance of considering the effects of human activities and landscape alteration for effective microrefugia conservation. [ABSTRACT FROM AUTHOR]

Using the SST k-ω turbulence model, a comprehensive numerical investigation was conducted to analyze the flow and heat transfer characteristics of steam within an isosceles trapezoidal cooling channel with pin-fin arrays modeled from the trailing edge of a F-class gas turbine high-temperature blade. The influence laws of various parameters, including the Reynolds number (Re, from 10,000 to 50,000), dimensionless pin-fin diameter (d/H, from 0.4 to 0.8), and dimensionless pin-fin spacing (S/H, from 1.6 to 2.4), on the flow and heat transfer performance of the isosceles trapezoidal cooling channel with pin-fin arrays were examined. Sensitivity analysis was employed to determine the relative significance of these influence parameters on the cooling performance of the isosceles trapezoidal channel with pin-fin arrays. Finally, the corresponding heat transfer and friction correlations within the investigated parameter range were developed. The research findings reveal that under different Reynolds numbers, as the dimensionless pin-fin diameter increases from 0.4 to 0.8, the friction factor within the isosceles trapezoidal cooling channel with pin-fin arrays increases by a factor of 3.25 to 3.41, while the overall average Nusselt number improves by 31.05% to 37.41%. Conversely, when the dimensionless pin-fin spacing increases from 1.6 to 2.4, the friction factor within the isosceles trapezoidal cooling channel with pin-fin arrays decreases by 67.38% to 69.18%, accompanied by a reduction in the overall average Nusselt number by 24.95% to 31.14%. When both the flow performance and heat transfer performance are taken into account, the importance of the influence parameters ranks as follows: Reynolds number, pin-fin diameter, and pin-fin spacing. It also suggests that smaller pin-fin diameters and larger pin-fin spacing should be selected in the design stage based on the variation laws of integrated thermal-hydraulic performance. The results may provide valuable references and insights for the design of steam cooling structures within high-temperature turbine blade trailing edge channels in advanced gas turbines. [ABSTRACT FROM AUTHOR]

Variable camber wing technology stands out as the most promising morphing technology currently available in green aviation. Despite the ongoing advancements in smart materials and compliant structures, they still fall short in terms of driving force, power, and speed, rendering mechanical structures based on kinematics the preferred choice for large long-range civilian aircraft. In line with this principle, this paper introduces a linkage-based variable camber trailing edge design approach. Covering coordinated design, internal skeleton design, flexible skin design, and drive structure design, the method leverages a two-dimensional supercritical airfoil to craft a seamless, continuous two-dimensional wing full-size variable camber trailing edge structure, boasting a 2.7 m span and 4.3 m chord. Given the significant changes in aerodynamic load direction, ground tests under cruise load utilize a tracking-loading system based on tape and lever. Results indicate that the designed single-degree-of-freedom Watt I mechanism and Stephenson III drive mechanism adeptly accommodate the slender trailing edge of the supercritical airfoil. Under a maximum cruise vertical aerodynamic load of 17,072 N, the structure meets strength requirements when deflected to 5°. The research in this paper can provide some insights into the engineering design of variable camber wings. [ABSTRACT FROM AUTHOR]

This study investigates the effect of thermal barrier coatings (TBCs) on the temperature distribution throughout a first-stage high-pressure aero-engine gas turbine rotor blade. The temperature changes on the naked and TBC-coated blade surfaces were investigated using computational models in ANSYS. The results showed a considerable drop in maximum temperature after using yttum-stabilized zirconia (YSZ) as a TBC, demonstrating its efficiency in alleviating thermal stresses. A comparative investigation of various TBC materials revealed varying degrees of heat resistance, with those with lower thermal conductivities. YSZ brought down the maximum temperature of the blade body by 18%. Lanthanum zirconate (La2Zr2O7) showed the best results, bringing down the maximum temperature by 19.5% compared to YSZ. These findings highlight the need to evaluate material qualities other than heat resistance when selecting TBCs for aerospace applications. This study underlines TBCs’ potential to improve the durability and performance of gas turbine rotor blades under high-temperature operating conditions. Furthermore, it suggests future research directions, such as investigations into TBC mechanical properties, erosion resistance, and long-term durability of TBCs, as well as the development of novel TBC formulations and manufacturing techniques to advance aerospace technology and ensure the sustainability of gas turbine operations.

Acoustic measurements were performed using microphone downstream of a 2-D wind turbine blade section in wind tunnel. The experiments have been carried out in both static and oscillatory pitching cases. The latter is usually experienced by the blades in actual circumstances. The microphone was 1.5 chords downstream of the airfoil and the measurements were conducted at three transverse positions, i.e. behind the trailing edge, midway between the trailing edge and the ground and very close to the ground. A CFD simulation of the flowfield has also been conducted using Fluent to correlate the acoustic behavior to the phenomena observed in the flowfield around the blade. The results show that the acoustic noise heard by a listener located on the ground is higher and stronger than that positioned downstream of the trailing edge, showing the ground effect on acoustic noise reverberation. The aerodynamic noise heard by the listener, changes from a treble to bass sound as the angle of attack increases. Beyond stall, the flow is dominated by the vortices shed into wake and the acoustic noises would be at very low frequencies which would result in a bass sound accompanied by structural vibration. In high angle of attack range, such noises can hardly be heard by a normal person but have a very destructive role on blade structure. [ABSTRACT FROM AUTHOR]

Reducing the tonal noise from airfoil instabilities has attracted significant interest from the aeronautical community in the past few years. The aim of this paper is to investigate the effect of structured porous trailing edges on the tonal noise reduction performance of a symmetrical NACA 0012 airfoil. Detailed parametric testing was performed in an open-jet wind tunnel between the baseline solid trailing edge and seventeen structured porous trailing edges with different sub-millimeter-scale pores. The experimental results demonstrate that structured porous trailing edges can reduce the noticeable tonal noise of the symmetrical NACA 0012 airfoil. Moreover, the design parameters for the structured porous edges have slightly different impacts on the tonal noise reduction performance between a zero angle of attack (α = 0°) and a non-zero angle of attack (α = 10°): better airfoil tonal noise reduction is due to the porous parameters of small pore coverage, small-to-moderate chordwise spacing, and moderate spanwise spacing at α = 0°. On the other hand, the optimal combination of the structured porous edge at α = 10° is the configuration with larger pore coverage, smaller chordwise spacing, and spanwise spacing. [ABSTRACT FROM AUTHOR]

As ongoing climate change drives suitable habitats to higher elevations, species ranges are predicted to follow. However, observed range shifts have been surprisingly variable, with most species differing in rates of upward shift and others failing to shift at all. Disturbances such as fires could play an important role in accelerating range shifts by facilitating recruitment in newly suitable habitats (leading edges) and removing adults from areas no longer suited for regeneration (trailing edges). To date, empirical evidence that fires interact with climate change to mediate elevational range shifts is scarce. Resurveying historical plots in areas that experienced climate change and fire disturbance between surveys provides an exciting opportunity to fill this gap. To investigate whether species have tended to shift upslope and if shifts depend on fires, we resurveyed historical vegetation plots in North Cascades National Park, Washington, USA, an area that has experienced warming, drying, and multiple fires since the original surveys in 1983. We quantified range shifts by synthesizing across two lines of evidence: (1) displacement at range edges and the median elevation of species occurrences, and (2) support for the inclusion of interactions among time, fire and elevation in models of species presence with elevation. Among species that experienced fire since the original survey, a plurality expanded into new habitats at their upper edge. In contrast, a plurality of species not experiencing fire showed no evidence of shifts, with the remainder exhibiting responses that were variable in magnitude and direction. Our results suggest that fires can facilitate recruitment at leading edges, while species in areas free of disturbance are more likely to experience stasis. [ABSTRACT FROM AUTHOR]

The present paper examines the use of modified dual-wavelength sawtooth serrations introduced at the trailing edge (TE) of a National Advisory Committee for Aeronautics (NACA) 65 (12)-10 airfoil as a passive means for the control of airfoil broadband noise. The studies are conducted for different parameters such as serration wavelengths (λ), serration amplitudes (h) as well as (hꞌ) modified amplitude to determine the best serration parameter which provides higher noise reductions. The reduction of noise level brought by the modified dual-wavelength sawtooth serrations at the TE is about 4 dB, while it is about 3.3 dB for the simple ones. It reveals that the modified sawtooth can provide a substantial reduction of self-noise alongside the interaction noise over an extensive range of frequencies which indicates the existence of strong far-field destructive interference (i.e., feedback) from low to mid-frequency ranges (i.e., 1.5 - 5 kHz). The TE serrated airfoils show lower acoustic emissions as compared to baseline although they exhibit a common behavior for all emission angles. The large noise decrease provided by the dual-wavelength sawtooth may be because of the significant reductions in the scattering intensity of sound as well as strong far-field destructive interference owing to the presence of two roots between the two successive maximum amplitude peaks. [ABSTRACT FROM AUTHOR]

The paper presents an analysis of the influence on the performance of multi-spool axial turbines of aircraft engines of the factors that are traditionally not taken into account when calculating the characteristics using the three-dimensional numerical modeling as well as the mutual influence of spools on each other. By the example of a two-stage cooled turbine of an aircraft engine, the influence of these factors on the efficiency and throughput of the turbine spools was evaluated. An approach to the correction of characteristics to improve their accuracy when transferring them to the thermodynamic model of the engine was taken. [ABSTRACT FROM AUTHOR]

The flow field structure and pressure pulsation characteristics in two series of trailing edges of a centrifugal pump are investigated using the SST k-w turbulence model. Series 1 involves varying the impeller exit angle, and Series 2 involves varying the impeller exit shape. The entropy generation rate analysis method is used to evaluate the numerical simulation results. Vortex cores within the flow field are identified by applying the Ω criterion. The influence of different trailing edge configurations on the energy loss characteristics of the pumps is explored. The dynamic mode decomposition (DMD) method is used to analyze pressure pulsations at the volute considering unsteady flows in centrifugal pumps with different trailing edge shapes. The findings suggest that different trailing edge shapes can be used to adjust the energy loss proportions in various components of the pump. In Series 1, the efficiency remains nearly constant with changes in the outlet angle on both sides of the trailing edge. In Series 2, the efficiency is enhanced by 1.18% with the elliptical edge shape on both sides (EBS) compared to the original trailing edge (OTE) shape. In Series 1 and Series 2, greater entropy generation rates are accompanied by greater pressure pulsations at the pump outlet. The DMD results demonstrate a noticeable impact of the different trailing edges on the pressure distribution of various modes within the volute. Moreover, the impeller outlet pressure inhomogeneity coefficient changes under different modes. This study holds great significance for selecting the appropriate trailing edges for centrifugal pumps. [ABSTRACT FROM AUTHOR]

Acoustic measurements were performed using microphone downstream of a 2-D wind turbine blade section in wind tunnel. The experiments have been carried out in both static and oscillatory pitching cases. The latter is usually experienced by the blades in actual circumstances. The microphone was 1.5 chords downstream of the airfoil and the measurements were conducted at three transverse positions, i.e. behind the trailing edge, midway between the trailing edge and the ground and very close to the ground. A CFD simulation of the flowfield has also been conducted using Fluent to correlate the acoustic behavior to the phenomena observed in the flowfield around the blade. The results show that the acoustic noise heard by a listener located on the ground is higher and stronger than that positioned downstream of the trailing edge, showing the ground effect on acoustic noise reverberation. The aerodynamic noise heard by the listener, changes from a treble to bass sound as the angle of attack increases. Beyond stall, the flow is dominated by the vortices shed into wake and the acoustic noises would be at very low frequencies which would result in a bass sound accompanied by structural vibration. In high angle of attack range, such noises can hardly be heard by a normal person but have a very destructive role on blade structure.

Purpose: The knowledge of spall propagation rate is highly crucial for estimating the remaining useful life of a spalled bearing. The actual mechanism for spall growth is not yet fully understood, however, it is considered that the stress and strain behavior at the spall edge can provide a glimpse of the tendency for crack development and spall progression. Method: This work presents a new dynamic impact force model for evaluating the fault growth parameters for both localized and extended outer race faults under two possible cases of ball impact, termed as 'Impact Under Compression (IUC)' and 'Free Impact (FI)'. Results and Conclusion: The simulation results revealed that both the radial load and speed favor spall propagation in the case of IUC, whereas the same remains unaffected by the radial load in FI condition and exhibits non-monotonous behavior with increasing speed. Moreover, the defect geometry shows a mixed influence on the behavior of defect growth parameters. [ABSTRACT FROM AUTHOR]

This study explores a novel flow control approach for enhancing the energy harvesting performance of an oscillating foil, which is a promising technology for harvesting renewable energy from wind and ocean currents. This approach involves placing a cylindrical spoiler structure at the trailing edge of the foil and investigating the effects of its diameter and spacing on the energy harvesting efficiency. The results show that the spoiler cylinders can significantly increase the energy harvesting efficiency of the foil by up to 19.26% compared to the case without them. The optimal configuration for the spoiler cylinders is found to be 11.0% of c in diameter, 0.5% of c in transverse spacing, and 0 in longitudinal spacing. Moreover, this flow control method is proven to be highly effective under a wide range of motion kinetic parameters. The findings of this study provide technical guidance for the design and implementation of oscillating foil energy harvesting devices, highlighting their practical engineering value. [ABSTRACT FROM AUTHOR]

Background and Aims Marine heatwaves (MHWs) are widely recognized as pervasive drivers of ecosystem change, yet our understanding of how different MHW properties mediate ecological responses remains largely unexplored. Understanding MHW impacts on foundation species is particularly important, given their structural role in communities and ecosystems. Methods We simulated a series of realistic MHWs with different levels of intensity (Control: 14 °C, Moderate: 18 °C, Extreme: 22 °C) and duration (14 or 28 d) and examined responses of two habitat-forming kelp species in the southwest UK. Here, Laminaria digitata reaches its trailing edge and is undergoing a range contraction, whereas Laminaria ochroleuca reaches its leading edge and is undergoing a range expansion. Key Results For both species, sub-lethal stress responses induced by moderate-intensity MHWs were exacerbated by longer duration. Extreme-intensity MHWs caused dramatic declines in growth and photosynthetic performance, and elevated bleaching, which were again exacerbated by longer MHW duration. Stress responses were most pronounced in L. ochroleuca , where almost complete tissue necrosis was observed by the end of the long-duration MHW. This was unexpected given the greater thermal safety margins assumed with leading edge populations. It is likely that prolonged exposure to sub-lethal thermal stress exceeded a physiological tipping point for L. ochroleuca , presumably due to depletion of internal reserves. Conclusions Overall, our study showed that exposure to MHW profiles projected to occur in the region in the coming decades can have significant deleterious effects on foundation kelp species, regardless of their thermal affinities and location within respective latitudinal ranges, which would probably have consequences for entire communities and ecosystems. [ABSTRACT FROM AUTHOR]

Additive manufacturing allows the fabrication of relatively complex cooling structures, such as triply periodic minimal surface (TPMS), which offers high heat transfer per unit volume. This study shows the turbulent flow heat transfer and thermal stress of the Diamond-TPMS topology in the gas turbine blade trailing edge channel. The thermal-fluid-solid analysis of the Diamond-TPMS structure, made of directionally solidified GTD111, at the nearly realistic gas turbine condition is executed, and the results are compared with the conventional pin fin array at the Reynolds number of 30,000. Compared to the baseline pin fin structure, the Diamond-TPMS model distributes flow characteristics more uniformly throughout the channel. The overall heat transfer enhancement, friction factor ratio, and thermal performance are increased by 145.3%, 200.9%, and 32.5%, respectively. The temperature, displacement, and thermal stress in the Diamond-TPMS model are also distributed more evenly. The average temperature on the external surface in the Diamond-TPMS model is lower than the baseline pin fin array by 19.9%. The Diamond-TPMS network in the wedge-shaped cooling channel helps reduce the volume displacement due to the material thermal expansion by 29.3%. Moreover, the volume-averaged von Mises stress in the Diamond-TPMS structure is decreased by 28.8%. [ABSTRACT FROM AUTHOR]

To investigate the effect of the different wrap angles from the hub to the shroud surface in the space diffuser (i.e., the trailing edge stacking style) on the principle of corner separation vortex flow, a numerical simulation method has been conducted in a multistage submersible pump. Building a linear equation on the profile line of the diffuser trailing edge to optimize the wrap angle on every spanwise from the hub to the shroud, and the mapping response relationship between the wrap angle difference and the hydraulic performance in the space diffuser has been analyzed. Under the variable wrap angle difference ( Δ ϕ = ϕ h u b − ϕ s h r o u d ), the secondary flows in different directions, non-uniformity, diffuser efficiency, and pressure recovery are compared. The positive wrap angle difference (i.e., the shroud wrap angle is smaller than the hub one) improves the strength of the secondary flow and partly corner separation vortex in the diffuser, so the hydraulic characteristic of positive cases is better than the negative wrap angle difference. Moreover, in scheme A (in which the hub wrap angle is constant and the shroud wrap angle decreasing), the transversal secondary flow has been weakened, the low-energy fluid located in the corner has been suppressed, the extensional secondary flow has been increased, the diffuser hydraulic performance has been improved, and unidirectionally increases with the wrap angle difference increasing. When the shroud wrap angle is constant, the extensional secondary flow has been enhanced by the increasing hub wrap angle. Meanwhile, the increasing extensional secondary flow has been countered by the deteriorating extensional flow at the diffuser inlet and transversal secondary flow, the diffuser hydraulic performance increases and then decreases as the wrap angle difference increases, with an optimal wrap angle difference is about 20°. [ABSTRACT FROM AUTHOR]

The nozzle guide vane, which is a stationary part of a gas turbine, is a critical component of gas turbine engines because it must operate under harsh conditions with high pressure and temperature. Unfortunately, when a gas turbine runs for a long time, the turbine vane is subjected to repeated thermal load. This increases the possibility of fatigue damage and crack failure, thereby reducing the vane material's lifespan. In practice, the risk of failure at the trailing edge (TE) of a turbine vane is very high due to the reasons of shape configuration and cooling performance. The TE damage disturbs the flow physics of compressible air passing the vane TE, resulting in flow phenomena and heat convection. The study aims to numerically investigate the effects of damaged surfaces at the TE of a turbine vane on its flow behavior using computational fluid dynamics (CFD) with the SST k-w turbulence model. To simplify the simulation, the effects of the TE failure are presented by using two basic patterns, i.e., long (continuous) cutback damage, and two-short (discrete) cutback damage. To complete the investigation, a further study on the effects of repaired surfaces is included as well. The numerical results show the effects of damaged and repaired surfaces on flow behavior, particularly the vortex formation and the level of turbulent kinetic energy (TKE) in the TE region. Specifically, the damaged vane surface significantly increases the TKE level in the TE region, particularly the two-short damaged surface, which TKE shoots up to 7000-8000 m2/s2. Meanwhile, TKE in the normal and long damaged case is around 1500 and 4000 m2/s2. With the restoration of the vane surfaces, it can reduce the TKE level in the TE region. For instance, TKE is uniformly around 1750 m2/s2 for the long repaired surface.

"When Empathy Opens" proposes an integration of self-psychological and -relational models of therapeutic action. The author argues that consistently approaching patients through the practice of Kohut's empathy evokes "a leading edge" transference that opens up the treatment relationship by orienting it toward facilitating the patient's pursuit of what is adaptive and developmental for them. This orientation then can guide the overall treatment process. The author also maintains that this practice of Kohutian empathy contributes to the emergence of impasses outlined by Stephen Mitchell, so that they can be constructively addressed in a transformative way that opens the treatment relationship further, beyond a self-object tie, so it becomes more fluid and multi-faceted. Winnicott's "leading edge" ideas about destruction and survival and breakdown supplement this self-relational integrative model. [ABSTRACT FROM AUTHOR]

Variable camber wing technology stands out as the most promising morphing technology currently available in green aviation. Despite the ongoing advancements in smart materials and compliant structures, they still fall short in terms of driving force, power, and speed, rendering mechanical structures based on kinematics the preferred choice for large long-range civilian aircraft. In line with this principle, this paper introduces a linkage-based variable camber trailing edge design approach. Covering coordinated design, internal skeleton design, flexible skin design, and drive structure design, the method leverages a two-dimensional supercritical airfoil to craft a seamless, continuous two-dimensional wing full-size variable camber trailing edge structure, boasting a 2.7 m span and 4.3 m chord. Given the significant changes in aerodynamic load direction, ground tests under cruise load utilize a tracking-loading system based on tape and lever. Results indicate that the designed single-degree-of-freedom Watt I mechanism and Stephenson III drive mechanism adeptly accommodate the slender trailing edge of the supercritical airfoil. Under a maximum cruise vertical aerodynamic load of 17,072 N, the structure meets strength requirements when deflected to 5°. The research in this paper can provide some insights into the engineering design of variable camber wings.

Using the SST k-ω turbulence model, a comprehensive numerical investigation was conducted to analyze the flow and heat transfer characteristics of steam within an isosceles trapezoidal cooling channel with pin-fin arrays modeled from the trailing edge of a F-class gas turbine high-temperature blade. The influence laws of various parameters, including the Reynolds number (Re, from 10,000 to 50,000), dimensionless pin-fin diameter (d/H, from 0.4 to 0.8), and dimensionless pin-fin spacing (S/H, from 1.6 to 2.4), on the flow and heat transfer performance of the isosceles trapezoidal cooling channel with pin-fin arrays were examined. Sensitivity analysis was employed to determine the relative significance of these influence parameters on the cooling performance of the isosceles trapezoidal channel with pin-fin arrays. Finally, the corresponding heat transfer and friction correlations within the investigated parameter range were developed. The research findings reveal that under different Reynolds numbers, as the dimensionless pin-fin diameter increases from 0.4 to 0.8, the friction factor within the isosceles trapezoidal cooling channel with pin-fin arrays increases by a factor of 3.25 to 3.41, while the overall average Nusselt number improves by 31.05% to 37.41%. Conversely, when the dimensionless pin-fin spacing increases from 1.6 to 2.4, the friction factor within the isosceles trapezoidal cooling channel with pin-fin arrays decreases by 67.38% to 69.18%, accompanied by a reduction in the overall average Nusselt number by 24.95% to 31.14%. When both the flow performance and heat transfer performance are taken into account, the importance of the influence parameters ranks as follows: Reynolds number, pin-fin diameter, and pin-fin spacing. It also suggests that smaller pin-fin diameters and larger pin-fin spacing should be selected in the design stage based on the variation laws of integrated thermal-hydraulic performance. The results may provide valuable references and insights for the design of steam cooling structures within high-temperature turbine blade trailing edge channels in advanced gas turbines.

Reducing the tonal noise from airfoil instabilities has attracted significant interest from the aeronautical community in the past few years. The aim of this paper is to investigate the effect of structured porous trailing edges on the tonal noise reduction performance of a symmetrical NACA 0012 airfoil. Detailed parametric testing was performed in an open-jet wind tunnel between the baseline solid trailing edge and seventeen structured porous trailing edges with different sub-millimeter-scale pores. The experimental results demonstrate that structured porous trailing edges can reduce the noticeable tonal noise of the symmetrical NACA 0012 airfoil. Moreover, the design parameters for the structured porous edges have slightly different impacts on the tonal noise reduction performance between a zero angle of attack (α = 0°) and a non-zero angle of attack (α = 10°): better airfoil tonal noise reduction is due to the porous parameters of small pore coverage, small-to-moderate chordwise spacing, and moderate spanwise spacing at α = 0°. On the other hand, the optimal combination of the structured porous edge at α = 10° is the configuration with larger pore coverage, smaller chordwise spacing, and spanwise spacing.

The wind turbine blade trailing edge (TE) is frequently exposed to compressive loading and can even be damaged under complex operating conditions. Among the most typical TE failure modes is the adhesive-joint failure, so it is necessary to evaluate the structural behavior of the adhesive joints in TE under compressive loading. In this regard, an improved testing method was proposed for blade subcomponents. Specifically, the experiment was performed on a composite TE structural specimen under compressive loading to reveal its internal failure mechanism. The results showed that when the TE specimen was compressed under increasing load, buckling deformation occurred gradually at the sandwich laminates. Also, the bending deformations of the laminates on the suction and pressure sides were different in the bonding region. The resultant shearing effect led to the structural adhesive undergoing brittle fracture, which then triggered debonding and extension, finally causing the debonding failure of the trailing-edge specimen. To guarantee the safety of a blade under edge-wise loading, it is suggested that the structural strength of the TE should be emphasized during the blade design process. [ABSTRACT FROM AUTHOR]

Abstract A numerical analysis method of trailing edge deboning is proposed in this paper. Using this method, multiple repair parameters can be quantified by analyzing aerodynamic responses and structural characteristics of the trailing edge. This method can be applied to three types of trailing edge, including blunt trailing edge, transitional trailing edge, and pointed trailing edge. In this study, the repair parameters are divided into two types, including the internal parameters that can affect the bonding strength and the external parameters that can affect the stiffness and aerodynamic shape. The main research steps are as follows: First, a repair structure shell‐body model was developed. Second, static tensile tests were carried out using 49 specimens, covering two lap joint types and seven bonding thicknesses. Finally, nine different repaired trailing edge models were developed using Ansys/Fluent for each two two‐dimensional airfoil. A 30–40 m section of a 71 m blade was used to develop a three‐dimensional (3D) rotating model with the repaired trailing edge. The simulation results show that the two internal parameters, overlap length and the slope of adhesive joints, are the key to improving the bonding performance of the pointed trailing edge. In addition, the bonding thickness range of 1–10 mm is proved by the experiment results and numerical analysis to be sufficient for good bonding performance. Besides this, the influence of the repair height on the aerodynamic pressure distribution and lift coefficient is much greater than the repair width, and the torque and power of the repaired 3D blade model are 1.91% higher than that of the original blade. This should further help provide an effective theoretical basis for determining the repair plan for a wind turbine blade.

This experimental study is focused on quantifying the effect of trailing edge flexibility on the performance of a three straight bladed vertical axis wind turbine, with a chord-to-diameter ratio c/D=0.16at a moderately high Reynolds number (based on diameter) ReD=4⋅105. The blades consist of NACA-0015 profiles that are fixed with a pitch angle β=6∘toe-out, and allow interchangeable trailing edges in the last 17% of their chord length. The research presented here provides a proof of concept for the improved performance of vertical axis wind turbines, due to the effect of flexibility at the trailing edge of their blades. We show that blades with semi-flexible trailing edge, can extend the range of rotor operating regimes, leading to an increase of approximately 10% in the performance of the turbine. An excess of flexibility results in diminished efficiencies.

Species' distributions are moving polewards in response to climate change, and although range expansions of relatively warm‐adapted species are widely reported, reports of range retractions in cool‐adapted species are less common. Here, we analysed species' distribution shifts for 76 cool‐adapted moths in Great Britain using citizen science occurrence records from the National Moth Recording Scheme over a 40‐year period. Although we find evidence for trailing edge shifts to higher latitudes, shifts in species' range centroids are oriented towards the north‐west, and are more closely correlated with directional changes in total precipitation than average temperature. We also found that species' local extinction risk is higher in areas where temperature is high and precipitation is low, but this risk diminishes as precipitation increases. Adaptation efforts should therefore focus on maintaining or increasing water availability as the climate continues to change. [ABSTRACT FROM AUTHOR]

This study presents a novel approach to parameterize the geometry of a morphing trailing-edge flap that allows its aerodynamics to be optimized while capturing the expected structural behavior of the flap. This approach is based on the finite frame element method, whereby the initial flap surface is defined as a structure with constraints that are similar to those of a morphing flap with passive skin. The initial shape is modified by placing a series of distributed loads on the surface. The finite frame element method is modified with rigid rotation corrections to maintain the initial element length without requiring nonlinear calculations and to achieve accurate surface-length results by only solving the linear FEM equations twice. The proposed method enables the shape of the morphing flaps to be rapidly formulated while maintaining the initial upper surface-length and trailing-edge angle. The constraints are inherently integrated into the algorithm, eliminating the need for unnecessary feasibility checks during the aerodynamic optimization. By using the proposed airfoil parameterization method, a case study was conducted by using a genetic algorithm to optimize the lift-to-drag ratio of the NACA 23012 airfoil flap starting at 0.7c with 10 degrees of deflection. The optimizer resulted in a structurally feasible morphing flap that achieved a 10% increase in the lift-to-drag ratio in the optimized angle of attack range. [ABSTRACT FROM AUTHOR]

During the course of recent studies on wings at low Reynold number, it was observed that wing corrugation is often assumed to play an important role as well. However, studies show that corrugation of the wing is intended for structural purposes, and not aerodynamics. Corrugated wings have the advantage of being light and sturdy. Therefore, the main aim of this study is to understand the flow behaviour of the corrugated insect-scale wing; by conducting, a geometric parametric study during a non-oscillatory flight at a particular low Reynolds number and at two different angles of attack. In this computational study, a 3-D section of the corrugated wing along the chord is considered. The lattice Boltzmann method offers an alternative framework compared to the Navier-Stokes simulations. An open-source Parallel Lattice Boltzmann Solver on a high-performance computing platform is used for this computational analysis. The present study shows that the flow-related performance of the corrugated wing in terms of forces and kinetic energy is predominantly governed by the geometric variations that can largely affect the formation of vortices and their mutual interaction. The study reveals that the presence of corrugation does not affect the enhancement of forces and corrugation near the leading edge generally affects the performance due to large flow separation affecting the suction.

This study explores a novel flow control approach for enhancing the energy harvesting performance of an oscillating foil, which is a promising technology for harvesting renewable energy from wind and ocean currents. This approach involves placing a cylindrical spoiler structure at the trailing edge of the foil and investigating the effects of its diameter and spacing on the energy harvesting efficiency. The results show that the spoiler cylinders can significantly increase the energy harvesting efficiency of the foil by up to 19.26% compared to the case without them. The optimal configuration for the spoiler cylinders is found to be 11.0% of c in diameter, 0.5% of c in transverse spacing, and 0 in longitudinal spacing. Moreover, this flow control method is proven to be highly effective under a wide range of motion kinetic parameters. The findings of this study provide technical guidance for the design and implementation of oscillating foil energy harvesting devices, highlighting their practical engineering value.

Additive manufacturing allows the fabrication of relatively complex cooling structures, such as triply periodic minimal surface (TPMS), which offers high heat transfer per unit volume. This study shows the turbulent flow heat transfer and thermal stress of the Diamond-TPMS topology in the gas turbine blade trailing edge channel. The thermal-fluid-solid analysis of the Diamond-TPMS structure, made of directionally solidified GTD111, at the nearly realistic gas turbine condition is executed, and the results are compared with the conventional pin fin array at the Reynolds number of 30,000. Compared to the baseline pin fin structure, the Diamond-TPMS model distributes flow characteristics more uniformly throughout the channel. The overall heat transfer enhancement, friction factor ratio, and thermal performance are increased by 145.3%, 200.9%, and 32.5%, respectively. The temperature, displacement, and thermal stress in the Diamond-TPMS model are also distributed more evenly. The average temperature on the external surface in the Diamond-TPMS model is lower than the baseline pin fin array by 19.9%. The Diamond-TPMS network in the wedge-shaped cooling channel helps reduce the volume displacement due to the material thermal expansion by 29.3%. Moreover, the volume-averaged von Mises stress in the Diamond-TPMS structure is decreased by 28.8%.

Understanding the demographic drivers of range contractions is important for predicting species' responses to climate change; however, few studies have examined the effects of climate change on survival and recruitment across species' ranges. We show that climate change can drive trailing edge range contractions through the effects on apparent survival, and potentially recruitment, in a migratory songbird. We assessed the demographic drivers of trailing edge range contractions using a long‐term demography dataset for the black‐throated blue warbler (Setophaga caerulescens) collected across elevational climate gradients at the trailing edge and core of the breeding range. We used a Bayesian hierarchical model to estimate the effect of climate change on apparent survival and recruitment and to forecast population viability at study plots through 2040. The trailing edge population at the low‐elevation plot became locally extinct by 2017. The local population at the mid‐elevation plot at the trailing edge gradually declined and is predicted to become extirpated by 2040. Population declines were associated with warming temperatures at the mid‐elevation plot, although results were more equivocal at the low‐elevation plot where we had fewer years of data. Population density was stable or increasing at the range core, although warming temperatures are predicted to cause population declines by 2040 at the low‐elevation plot. This result suggests that even populations within the geographic core of the range are vulnerable to climate change. The demographic drivers of local population declines varied between study plots, but warming temperatures were frequently associated with declining rates of population growth and apparent survival. Declining apparent survival in our study system is likely to be associated with increased adult emigration away from poor‐quality habitats. Our results suggest that demographic responses to warming temperatures are complex and dependent on local conditions and geographic range position, but spatial variation in population declines is consistent with the climate‐mediated range shift hypothesis. Local populations of black‐throated blue warblers near the warm‐edge range boundary at low latitudes and low elevations are likely to be the most vulnerable to climate change, potentially leading to local extirpation and range contractions. [ABSTRACT FROM AUTHOR]

Thermodynamic losses and blade erosion occur due to formation of wetness in the low-pressure steam turbine. By changing the trailing edge angle of turbine blade can reduce blade erosion and condensation losses. This research optimized the best of the trailing edge rotation to improve the turbine's operation at the low-pressure part of the steam turbines (thermodynamic losses and blade erosion) as passive method. In this paper, the integral of the number of droplets per volume (IND), the integral of the droplet average radius (IDR), the integral of wetness fraction (IWF), the integral of local entropy (ILE), and the integral of dynamic pressure (IDP) were considered as goals of optimization. The results introduce an optimal case (θ = − 0.84o counterclockwise) while improved IDR by 0.276%, increased IND by 0.0389%, improved IWF by 0.207%, reduced IDP by 0.054%, and increased ILE by 0.0074%. In addition, this optimization caused the erosion rate to be improved by 2.33% and the condensation losses to be decreased by 0.39%. [ABSTRACT FROM AUTHOR]

The paper investigated numerically the heat transfer and pressure loss characteristics of the converging matrix cooling channels for turbine trailing edges with response surface method. The three selected design factors are scale factor (SF), rib inclination angle (α) and channel wedge angle (β). The discussed range for the design factors, SF, α and β, are 2.5–10; 30°–60° and 1.5°–2.5°. And the investigated Reynolds number range is from 15,000 to 40,000. The turbulence model selected was SST k - ω model. It is newly found that the heat transfer and pressure loss characteristics of the converging matrix cooling channels depend heavily on the scaling effect. The matrix cooling channels with larger scale factor generally present higher heat transfer enhancement, higher pressure loss and lower overall thermal performance. In addition, the converging matrix cooling channels with smaller rib inclination angle and larger channel wedge angle present higher heat transfer enhancement and larger pressure loss. Among all the 13 cases, Case 9 with SF = 2.5, α = 45° and β = 1.5° has the highest averaged thermal performance factor under 6 Reynolds numbers. [ABSTRACT FROM AUTHOR]

A numerical analysis method of trailing edge deboning is proposed in this paper. Using this method, multiple repair parameters can be quantified by analyzing aerodynamic responses and structural characteristics of the trailing edge. This method can be applied to three types of trailing edge, including blunt trailing edge, transitional trailing edge, and pointed trailing edge. In this study, the repair parameters are divided into two types, including the internal parameters that can affect the bonding strength and the external parameters that can affect the stiffness and aerodynamic shape. The main research steps are as follows: First, a repair structure shell‐body model was developed. Second, static tensile tests were carried out using 49 specimens, covering two lap joint types and seven bonding thicknesses. Finally, nine different repaired trailing edge models were developed using Ansys/Fluent for each two two‐dimensional airfoil. A 30–40 m section of a 71 m blade was used to develop a three‐dimensional (3D) rotating model with the repaired trailing edge. The simulation results show that the two internal parameters, overlap length and the slope of adhesive joints, are the key to improving the bonding performance of the pointed trailing edge. In addition, the bonding thickness range of 1–10 mm is proved by the experiment results and numerical analysis to be sufficient for good bonding performance. Besides this, the influence of the repair height on the aerodynamic pressure distribution and lift coefficient is much greater than the repair width, and the torque and power of the repaired 3D blade model are 1.91% higher than that of the original blade. This should further help provide an effective theoretical basis for determining the repair plan for a wind turbine blade. [ABSTRACT FROM AUTHOR]

Cetaceans are important consumers in marine ecosystems, but few studies have quantified their climate responses. The rapid, directional warming occurring in the Northeast United States (NEUS) provides a unique opportunity to assess climate impacts on cetaceans. We used stranding data to examine changes to the distribution and relative abundance of odontocetes from 1996 to 2020 in both the NEUS and the Southeast United States (SEUS), which is not warming. We conducted simulations to determine the number of stranding events needed to detect a distributional shift for each species given the speed of the shift and the spatial variability in strandings. We compared observed shifts to climate velocity. Smaller sample sizes were needed to detect more rapid poleward shifts, particularly for species with low spatial variability. Poleward shifts were observed in all species with sufficient sample sizes, and shifts were faster than predicted by climate velocity. For species whose trailing edge of distribution occurred in the NEUS, the center of distribution approached the northern limit of the NEUS and relative abundance declined through time, suggesting shifts north out of US waters. The relative abundance of warm water species in the stranding record increased significantly in the NEUS while that of cool water species declined significantly as their distributions shifted north out of the NEUS. Changes in the odontocete community were less apparent in the SEUS, highlighting the importance of regional warming. Observed poleward shifts and changes in species composition suggest a reorganization of the odontocete community in the NEUS in response to rapid warming. We suggest that strandings provide a key dataset for understanding climate impacts on cetaceans given limitations of survey effort and modeling approaches for predicting distributions under rapidly changing conditions. Our findings portend marked changes to the distribution of highly mobile consumer species across international boundaries under continued warming. [ABSTRACT FROM AUTHOR]

Anthropogenic climate change is causing demographic shifts at species' range edges. Trailing edge populations, which may be genetically distinct and adapted to relative climate extremes, already are showing declines in some species. The associated loss of trailing edge genetic diversity may limit possibilities for future climate‐adaptive restoration. For plants with recalcitrant seed, such as oaks, that cannot tolerate conventional seed banking, we propose a novel approach to the conservation of climate‐threatened genetic diversity: dispersed, participatory field gene banking. In this collaborative model, trailing edge transplants are stewarded at dispersed sites across a species' projected regional refugia. In 2018, we initiated a pilot participatory field gene bank for the foundational, endemic California blue oak (Quercus douglasii), a species experiencing increasing climate‐related declines at its trailing edge. To evaluate seedling performance, the gene bank was designed as a set of 23 small, dispersed common gardens with paired local and trailing edge seeds. Trailing edge seedlings showed lower survival and growth relative to locals, yet they also showed lower levels of leaf disease and herbivory, traits that could confer an adaptive advantage in a more xeric future. The substantial early survival of translocated seeds suggests that participatory field gene banking may offer an effective means of preserving trailing edge genetic diversity for oaks, thereby maintaining genetic resources that could be critical for future climate change‐adaptive restoration. However, further observations are needed to confirm the strategy's longer‐term viability and evaluate evidence of local adaptation. [ABSTRACT FROM AUTHOR]

Sexing cetaceans typically requires extended periods of observation or expensive molecular methods. An alternative approach using photo‐identification may provide a cost‐effective, noninvasive method for assigning a sex to free‐ranging individuals. We investigated two methods for predicting the sex of common bottlenose dolphins (Tursiops truncatus) from Namibia, using the rate of change in dorsal fin (1) trailing edge marks or (2) surface features (scarring and lesions) and binary logistic regression models. Our results suggest animals with frequent and extensive changes to dorsal edge marks, or a high number/proportion of the dorsal fin covered in surface features are likely male, while those with little to no changes in dorsal edge marks or low numbers/proportion of surface features are likely female. Both sex prediction models performed reasonably well (accuracy: edge marks: 100%, surface features: 83%), with a high degree of consensus between models in sex predictions (78.6%). Our models are straightforward to implement and robust for the study population, providing useful insights into individuals' sex and population demographics. This reliable, inexpensive, and minimally invasive framework for assigning sex could be widely applicable, if population‐specific information of known sex individuals is included, due to the variable social systems and behaviors exhibited by Tursiops spp. [ABSTRACT FROM AUTHOR]

This study investigates the effects of serration angle on the three-dimensional flow field and noise reduction mechanism of a NACA6512-63 airfoil using large eddy simulation (LES) and spectral proper orthogonal decomposition (SPOD) techniques. The serration angle is defined as the ratio of serration wavelength (λ) to serration amplitude (h). The mean flow field analysis on suction side of serration reveals the outward flow towards the serration edges and the downwash flow between the valleys that generate the counter-rotating vortex pair. This flow alteration changes the serration effective angle of the serration, consequently affecting the noise reduction performance. Additionally, by comparing the general solution of Lyu's semi-analytical equation with the SPOD mode results, the noise reduction mechanism is examined, and the frequency range in which noise reduction occurs is analyzed. The linearly distributed multipole-like pressure patterns, similar to those in the semi-analytical solution, are observed in the low-frequency range for all three cases, with the λ /h = 0.3 case exhibiting the most effective noise reduction. The findings suggest that the local deviation of the turbulence axis, caused by the strong outward flow near the serration edges, can hinder the formation of the optimal pressure field distribution required for effective noise reduction. • Investigate the noise reduction mechanism of serration angle. • Counter-rotating vortex pair generated affects noise reduction performance. • Linearly distributed multipole pressure patterns observed in low-frequency. • Outward flow cause local deviation of turbulence axis, hindering noise reduction. [ABSTRACT FROM AUTHOR]

Research on aerodynamics on racing bicycles always develops from time to time. The various geometry of a time-trial helmet produces different characteristics of fluid flow, this is due to the relative movements of air that are in the area throughout the body shape of the helmet. Basically the fluid flow that passes on a racing bicycle helmet will produce a drag force, where this must be minimized in order to hinder the pace of drivers to achieve maximum speed, so drivers should pay attention to how to design the geometry of helmet that should be used. Computational fluid dynamics (CFD) method is used to simulate the case studies in this research. In this study, four kinds of models trailing edge geometry was varied to determine where the most optimal in accepting the drag force. The validation was also conducted to determine the suitability of this study with prior research, where in this validation the results of this study are compared with the research owned (Sims and Jenkins, 2011). The results of this validation show that the resulting drag coefficient has a very small difference of 0.001. The four models are simulated with Reynold number values of 7.14 × 104, 1.00 × 105, and 1.16 × 105. The results of this study indicate that with differences in the geometry of the trailing edge affect the drag force that occurs. From the research result when Reynold 7.0 x 10 ^ 4, the drag force produced by model 3 is bigger than model 1 and 2 which is equal to 0.182 N. Whereas on Reynold which is bigger 1.16 x 10 ^ 5 model 3 receives drag smaller than model 1 and 2 which is equal to 0.283 N. In the world of bicycle racing, the difference in the small drag force affects the speed of the bicycle and affects the resulting victory.

• Opening the trailing edge reduced its chordwise stiffness by up to three orders of magnitude. • Internal-external pressure differences caused the trailing edge to partially collapse. • Passive morphing was achieved with a low material failure index (<0.15) • An open trailing edge reduced the simulated thrust force on the blade by 55% Numerical simulations and lab-scale experiments are used to evaluate three passively morphing trailing edge designs for a composite tidal turbine blade. The designs include a closed trailing edge, an open trailing edge, and a corrugated trailing edge. It is shown that geometric stiffness, as well as material stiffness, play key roles in achieving the desired deformation of the trailing edge. One trailing edge design is down-selected for further investigation via full-scale numerical simulations. These simulations demonstrate how the composite lay-up influences the morphing response of the trailing edge and its likelihood of material failure. The influence of camber is also investigated in terms of both material behaviour and hydrodynamic performance. Finally, the potential for bend-twist coupling of the laminate skins is explored. [ABSTRACT FROM AUTHOR]