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Understanding how protrusions, such as fins attached to flat or streamlined bodies, affect aerodynamics, especially in high-speed contexts, is vital for aerospace applications. These protrusions significantly influence overall aerodynamics and require a comprehensive understanding for accurate analysis and prediction of aerodynamic performance. This understanding is particularly critical in supersonic flight, where even minor aerodynamic disturbances can impact vehicle stability and efficiency. Therefore, a thorough understanding of protrusion-induced flow phenomena is essential for advancing aerospace engineering and improving supersonic vehicle performance and safety. The present paper focuses on the complex supersonic flow over a vertical fin, using a combination of experimental and computational methods. The study aims to understand how variations in fin height influence the behavior of the Lambda shock and any resulting changes in shock length. Specifically, the paper investigates different fin height-to-diameter (H/D) ratios ranging from 0.5 to 1.5 in steps of 0.25. To achieve this, both experimental testing in a supersonic wind tunnel and numerical simulations using the commercial CFD tool ANSYS-FLUENT are employed. Through this dual approach, the paper seeks insights into the characteristics of the Lambda shock and its effects on key aerodynamic parameters, such as shock strength and drag coefficient. By thoroughly investigating these aspects, the paper contributes to a deeper understanding of the complex flow phenomena associated with supersonic flow over vertical fins, potentially guiding the design and optimization of aerospace vehicles. The outcomes indicate that a fin height of 12 mm (H/D=1.0) provides the best balance in terms of pressure distribution, Lambda shock length, and drag coefficient, making it the optimal choice for enhancing aerodynamic stability and performance in supersonic conditions.

This paper presents a bionic dual-fin underwater robot, inspired by the ocean sunfish, that achieves multiple swimming motions using only two vertically arranged fins. This work demonstrates that a mechanically simple platform can execute complex 2-D and 3-D motions through advanced control strategies, eliminating the need for auxiliary actuators. We control the two fins independently so that they can perform cooperative actions in the water, enabling the robot to perform various motions, including high-speed cruising, agile turning, controlled descents, proactive ascents, and continuous spiraling. The swimming performance of the dual-fin robot in executing multi-modal locomotion is experimentally analyzed through visual measurement methods and onboard sensors. Experimental results demonstrate that a minimalist dual-fin propulsion system of the designed ocean sunfish robot can provide speed (maximum cruising speed of 1.16 BL/s), stability (yaw amplitude less than 4.2°), and full three-dimensional maneuverability (minimum turning radius of 0.89 BL). This design, characterized by its simple structure, multiple motion capabilities, and excellent motion performance, offers a promising pathway for developing robust and versatile robots for diverse underwater applications.

Studies of solar access to the building envelope are key to effective daylighting and passive heating and cooling. Shading devices are not limited to awnings or light shelves. Partial overhangs, vertical shading fins, egg crating, brise‐soleils, pergolas, and so forth may be investigated given the range of BIM modeling characteristics. The designer can use building information modeling (BIM) to help evaluate the effectiveness of shading devices both to deny direct gain in warm months and to admit it in cold seasons. Since buildings are used year‐round, a rendering of shading conditions at a single moment in time is of limited usefulness. Solar animations are intended to overcome that limitation, and broadly include representational tools that depict the sun's movement over time—or more accurately the movement of shadows cast by the sun—whether over the span of a day, a season, or a year.

Monopile foundations are subjected to large environmental loads in the form of lateral loads from wind, seismic, water currents, which would exceed more than 30% of gravity loads. Providing fins to monopiles is one of the most viable options to decrease the foundation cost for wind turbine foundations and improve its lateral load carrying capacity in poor ground conditions. Numerical analyses were performed on monopiles with and without fins embedded in loose sand and soft clay. Pile material is considered as mild steel for all analyses. Initially, fins length, width, orientation and position were varied to evaluate the optimum fins size, position and orientation. After establishing optimum fin dimensions, position and orientations, lateral load analyses were performed on finned piles embedded in loose sand and soft clay. The results have shown that fins placed near the top portion of the piles are more effective than fins placed near the middle and bottom portions of the piles. Among various fin orientations, straight fins (or fins placed orthogonally) are the most effective ones and for the optimum fin efficiency as well as to avoid buckling, the fin width shall be 0.5 times pile diameter, and the fin length shall be half the pile length and this is found to be valid for finned piles embedded in both loose sand and soft clay. The monopile embedded in sand with fins placed at top carry 42% higher lateral load and whereas in soft clay it is 48% than monopiles.

In this research, a numerical analysis is accomplished aiming to investigate the effects of adding a new design fins arrangement to a vertical triplex tube latent heat storage system during the melting mechanism and evaluate the natural convection effect using Ansys Fluent software. In the triplex tube, phase change material (PCM) is included in the middle tube, while the heat transfer fluid (HTF) flows through the interior and exterior pipes. The proposed fins are triangular fins attached to the pipe inside the PCM domain in two different ways: (1) the base of the triangular fins is connected to the pipe, (2) the tip of the triangular fins is attached to the pipe and the base part is directed to the PCM domain. The height of the fins is calculated to have a volume equal to that of the uniform rectangular fins. Three different cases are considered as the final evaluation toward the best case as follows: (1) the uniform fin case (case 3), (2) the reverse triangular fin case with a constant base (case 12), (3) the reverse triangular fin case with a constant height (case 13). The numerical results show that the total melting times for cases 3 and 12 increase by 4.0 and 10.1%, respectively, compared with that for case 13. Since the PCM at the bottom of the heat storage unit melts slower due to the natural convection effect, a flat fin is added to the bottom of the heat storage unit for the best case compared with the uniform fin cases. Furthermore, the heat storage rates for cases 3 and 12 are reduced by 4.5 and 8.5%, respectively, compared with that for case 13, which is selected as the best case due to having the lowest melting time (1978s) and the highest heat storage rate (81.5 W). The general outcome of this research reveals that utilizing the tringle fins enhances the thermal performance and the phase change rate.

The oceanic whitetip shark ( Carcharhinus longimanus ) is globally understudied with major data deficits despite its global distribution. We present horizontal and vertical movement data by investigating habitat use of seven mature oceanic whitetip sharks equipped with fin-mounted satellite (SPOT/SPLASH) tags off of Moorea, French Polynesia. Sharks moved net distances ranging from 1,625 to 7,885 km over periods of 83 to 286 days at liberty. A total area of 1,467,157 km 2 was utilized by the sharks, spanning three exclusive economic zones (French Polynesia, Kiribati, and Cook Islands) and unmanaged international waters. A core area of 176,635 km 2 was identified within the Society Islands. Application of a two-state Hidden Markov Model differentiated movement along each individual track between a transient behavioral state (66% of movement) and an area-restricted searching behavioral state (34% of movement), revealing sharks tended to switch to residential behavior when associated with islands, seamounts, or bathymetric ridges. Thermal barriers, particularly sea surface temperatures of less than 26 °C, limit horizontal movement. Additional evidence of site fidelity for the largely oceanic species was observed with five of seven tagged sharks returning to Moorea during the study. Vertical movements reached a maximum depth of 270 m with 97% of their time spent at a depth shallower than 130 m. This study provides the first description of habitat use of C. longimanus in the South Pacific, contributing to the collective global knowledge of an enigmatic species as well as providing insight into its effective management in French Polynesia, a designated shark sanctuary.

In this paper, heat dissipation through a passive vertical plate fin heat sink via natural convection was numerically investigated. The influence of two nondimensional geometric parameters, fin spacing-to-thickness ratio and fin height-to-spacing ratio, on the heat sink’s thermal performance was evaluated. A mathematical model describing the three-dimensional steady-state problem of buoyancy-driven flow and heat transfer was formulated. The solution was obtained numerically using the finite volume method in Ansys Fluent. The model and numerical procedure were validated by comparing the numerical predictions with measurements acquired on a constructed experimental apparatus. The heat sink thermal performance was assessed based on a series of performance metrics: heat dissipation rate, heat transfer coefficient, overall thermal resistance, and fin efficiency. Fin spacing-to-thickness ratio was varied between 1.86 and 4.8. Heat dissipation rate displayed a clear peak at a value of approximately 2.6, which coincided with a minimum in the overall thermal resistance. The heat transfer coefficient initially grew steadily, but at higher values of fin spacing-to-thickness ratio, it began to stagnate. Fin efficiency consistently decreased across the investigated range. Fin height-to-spacing ratio was varied between 1.11 and 7.78. The heat dissipation rate increased almost linearly across this range, but when the mass-specific heat dissipation rate was considered, it yielded diminishing returns. The heat transfer coefficient likewise exhibited a plateauing trend, while fin efficiency decreased steadily across the investigated range of fin height-to-spacing ratio. The obtained numerical results provide guidelines for geometry selection and can serve as a foundation for further analyses and optimizations of passive heat sinks’ thermal performance.

Oscillating fins are devices designed to produce thrust through periodic undulating movements. However, these structures lack flexibility and often provide thrust in only one fixed direction. Observation and biological references suggest that the dorsal fin rays of seahorses can tilt longitudinally in the spine direction, changing the thrust direction. This study aims to analyze the dynamic effects of seahorse dorsal fin inclining and design a flexible bionic thruster based on this principle. Computational fluid dynamics analysis hypothesizes that fin inclination controls the net force direction in the vertical plane. A force sensor and pulley system test platform were constructed to examine the influences of wave features and the inclination angle on thrust in both vertical and horizontal directions, with discrete fin surfaces used to eliminate force interference. Force testing and snapshots indicate that wave velocity positively impacts net force magnitude, while fin inclination allows for control over force orientation. This tiltable oscillating fin thruster possesses more degrees of freedom, leading to better flexibility and providing controllable thrust orientation.

Important morphological and ecological modifications occur during the transition between pelagic and demersal phases in marine fish. However, it is still unknown how fast these shape changes may occur. We studied the shape changes of a common cryptobenthic fish, the triplefin Helcogrammoides chilensis (Cancino, 1960) during the shift from pelagic larvae to recently settled individuals, along rocky shores in central Chile during the austral summers of 2020 and 2021. The working hypothesis was that larval stages would show more allometry and faster shape changes in the head and the paired fins insertion than benthic juveniles, in preparation for their new environment. Shape changes were analyzed utilizing landmark-based geometric morphometrics, while age was estimated using sagittal otolith microstructure analysis. There was an important overlap in the size (length and weight) between older larvae and recently settled individuals (between 20 and 25 mm SL , and 0.08–0.17 g), nonetheless, the head shape and paired fins were clearly different between stages. Pelagic larvae (46–88 days post hatch) had a shorter pectoral fin base, a frontal mouth opening, and eyes located at the level of the tip of the upper jaw. Meanwhile, recently settled individuals (80–112 days post hatch) had wider, vertically positioned pectoral fins, mouths displaced to a vertical position, and eyes located upper and forward the head. Larvae experienced faster growth rates than settlers (0.24 vs. 0.02 mm day −1 , respectively), and the pattern of ontogenetic shape changes decreased two orders of magnitude after settlement. It is plausible that after the pelagic–demersal shift most of the fish’s energy was used in body structure rearrangement and incrementing body pigmentation, as an adaptation of cryptobenthic juvenile to the rocky reef.

Due to the low thermal conductivity of the phase change material and low thermal diffusion inside the phase change material, this study seeks to improve the melting response of a triple‐tube latent heat storage system via employing annular fins by optimizing their structural parameters, including the fin number, location, and dimensions. Natural convection effects are numerically evaluated considering different numbers and the locations of the fins, including fin numbers of 4, 10, 16, 20, and 30 in a vertical system orientation. The fins are attached to the inner and outer sides of the annulus, accommodating the phase change material between the inner and center tubes. The fins' number and location are identical on both sides of the annulus, and the volume of the fins is the same across all scenarios evaluated. The results show that the higher the number of fins used, the greater the heat communication between the fins and the phase change material layers in charge, resulting in faster melting and a higher rate of heat storage. Due to the limited natural convection effect and lower heat diffusion at the heat exchanger's bottom, an additional fin is added, and its thickness is assessed. The results show that the case with equal fin thickness, that is, both original fins and the new fin, performs the best performance compared with that for the cases with an added fin with thicknesses of 0.5, 1, and 2 mm. Eliminating an extra fin from the base of the system for the case with 30 fins increases the charging time by 53.3%, and reduces the heat storage rate by 44%. The overall melting time for the case with an added fin to the bottom is 1549 s for the case with 30 fins which is 85.8%, 34.2%, 18%, and 8.8% faster than the cases with 4, 10, 16, and 20 fins, respectively. This study reveals that further attention should be given to the position and number of annular fins to optimize the melting mechanism in phase‐changing materials‐based heat storage systems. This study seeks to improve the melting response of a triple‐tube latent heat storage system via annular fins by optimizing their structural parameters including the fin number, location, and dimensions. It reveals that further attention should be given to the position and number of annular fins to optimize the melting mechanism in phase‐changing materials‐based heat storage systems.