Heel Angle Research Articles

Unsteady Flow Behaviors and Vortex Dynamic Characteristics of a Marine Centrifugal Pump under the Swing Motion

Due to the effects of swing motion, the performances and internal flow characteristics of marine centrifugal pump undergo some unsteady variations in the marine environment. The hydraulic test system with six degree of freedom parallel motion platform is established to study the pump performance characteristics at the different heel angles of steady roll position and pitch position. The pump head gradually decreases as heel angle increases. The pump head has decreased by 7% to reach the minimum at the 15° heel angle of roll position. At the same heel angle, the head at the roll position is lower than that at the pitch position under the rated flow condition. The fluid in the impeller passage is subjected to the additional inertial force of roll motion or pitch motion under unsteady swing motion, inducing some flow bias phenomena in the velocity field. The unsteady development of flow velocity induces the intense vortex motion, and the shedding and dissipation of interblade vortices are affected. The periodic flow-induced pulsation characteristics obviously appear in the impeller passage. The pulsation periodicity and pressure amplitude are influenced due to the swing motion. The pitch motion induces the greater hydraulic excitation and fluid-induced vibration amplitude. In addition to the pressure pulsation at the low frequencies, the pulsation amplitude at 20 times the shaft frequency is evident under pitch motion.

The influence of flow field bottom effect and sand cloud effect on the hydrodynamic performance and stability of bottom trawling otter board under tilted attitudes

To explore how bottom and sand cloud effects influence the hydrodynamic performance and stability of bottom trawling otter board under tilted attitudes, this study combines numerical simulations by oval cambered otter board and flume tank experiments verification. By assessing drag and lift coefficients (CD,CL), center-of-pressure coefficients (Cpc, Cpb) and longitudinal moment (My) in different heel angles, the study evaluates the impact under the two effects on hydrodynamics and stability. Findings reveal that inward and outward tilting increases CD maximally under sand cloud effect, while minimizing it under broad-field only water conditions; CL is maximal under bottom effect and minimal under broad-field only water conditions. For forward and backward tilting, CD under sand cloud effect is greater than that under bottom effect, with minimal values in broad-field only water conditions; CL is maximal under bottom effect and minimal under broad-field only water conditions. Additionally, stability varies across different flow field conditions, deteriorating along the x-axis due to bottom and sand cloud effects, while maintaining relative stability along the y-axis and z-axis. This study demonstrates that the bottom effect and sand cloud effect alter the otter board's proximity to the seabed and the fluid viscosity, leading to differences in hydrodynamic performance and stability under inclined attitudes. The findings aim to provide insights for the use and design of bottom trawling otter boards, ensuring stability and safety under various operating conditions and attitudes.

Steadiness of technical variables as a determinant factor of performance in a virtual simulated regatta

ABSTRACT The aim of this investigation is to explore the relationship between Optimist sailing performance with boat steadiness as well as the steadiness of cyclic variables related to sailors’ technique, in the upwind leg of a regatta. Thirty-two sailors from the optimist class (16 bottom level and 16 top level) performed a regatta in a semi-immersive simulator which measures the instantaneous velocity, heading, boom, heel, and rudder angle and hiking effort. It was calculated the mean values as well as the short-term steadiness and long-term steadiness throughout the test. Top level and bottom level sailors were compared and the correlation between these variables and mean velocity were analysed. Significant differences were found between groups on mean values, STS values and LTS values as well as significant correlations ranging r values between 0.385 and 0.768. If the steadiness of sailing variables is considered, they appear as determinants of performance in Optimist class while this is not observed when analysing mean values.

RANSE simulations for unmanned sailboat performance prediction: Coupling aerodynamics and hydrodynamics in self-sailing

During the design phase of sailboats, naval architects typically employ hydrodynamic and aerodynamic models of the sailboat, utilizing a Velocity Prediction Program (VPP) to solve the equations of motion, thus determining the sailboat's speed and performance. Traditional methods for solving sailboat motion equations often employ simplified empirical formulas or costly experimental procedures, which yield less accurate results. This study presents the RANSE-based CFD software STAR-CCM + to comprehensively model the sailboat's hull-sail-rudder assembly. By implementing overset grid technology and the Volume of Fluid (VOF) model, the paper aims to couple the solution of aerodynamic and hydrodynamic forces under wind influence and introduces PID rudder control technology to maintain a balance of forces and convergence of motion state. This approach enables the prediction of the sailboat's speed and performance, such as yaw angle, heel, and rudder angle. Results demonstrate minimal variations in sailboat speed (<0.05 m/s) and heading (<0.1°) in upwind, downwind and reaching sailing conditions, underscoring the method's feasibility and advocating for further research into self-sailing performance.

Numerical investigation on the effects of heel on the aerodynamic performance of wing sails

The utilization of wind-assisted propulsion technology could reduce ship fuel consumption and emission of pollutants. In the study, the effect of steady heel angles on the aerodynamic characteristics of wing sails was investigated. Full-scale three-dimensional simulations with the ship's superstructure were conducted at heel angles of 0°–15° in all apparent wind directions. The correctness of the numerical computations is verified by comparing them with the wind tunnel experimental data. Overall, the heel is detrimental to the capture of wind energy by the wing sails. The aerodynamic forces of the sail system decrease with increasing heel angles. Specifically, the average thrust performance is attenuated by 4.7%, 13.5% and 20.5%, respectively, at heel angles of 5°, 10°, and 15° compared to the upright condition. Due to changes in the airflow distribution around the sails, the aerodynamic force of sails in heeled to windward and heeled to leeward decreases by the reduced area of the low-pressure zone on the suction side and the high-pressure zone on the pressure side, respectively. Finally, a prediction scheme for assessing the effect of rolling motion on sail performance is proposed by steady heel results.

Distal phalanx radiographic grading features in long‐toe, underrun heel in Egypt Baladi donkeys (Equus asinus)

SummaryBackgroundLong‐toe, underrun heel conformation is a term referring to a long toe, collapsed frog and atrophied heels in equids, including donkeys. However, data on the radiological evaluation and classification of the long‐toe, underrun heel conformation in the donkey are relatively limited.ObjectivesThe present study aimed to determine the relationship between the dorsal hoof wall angle and the radiological angular and linear features of the distal phalanx in long‐toe, underrun heel conformation in Egypt Baladi donkeys.Study designPost‐mortem collected feet.MethodsForty‐seven front hooves with long‐toe, underrun heels from cadavers were radiographically examined. Lateromedial radiometric parameters included dorsal hoof wall angle, heel angle, distal phalanx angle, distal phalanx solar border angle, coronet angle, axis of the distal phalanx angle, proximal palmar cortex angle, distal phalanx to ground distance, distal phalanx to frog distance, distal phalanx to toe distance, foot length and hoof balance%. Long‐toe, underrun heel cadaver feet were classified into four groups according to the dorsal hoof wall angle (DHWA).ResultsThe DHWA of the first group was less than 58.25°–54° (&lt;58.25°:54°), the second group was less than 54°–52° (&lt;54°:52°), the third group was less than 52°–47° (&lt;52°:47°), and the fourth group was less than 47° (&lt;47°). From the first to the fourth groups DHWA, heel angle (HA), distal phalanx solar border angle (P3BA), distal phalanx angle (P3A), axis of the distal phalanx angle (LP3A), proximal palmar cortex angle (PPCA), distal phalanx to frog distance (P3F) and foot length (FL) were decreased, while the coronet angle (CA), distal phalanx to toe distance (P3T) and hoof balance (HB) percentages were increased. Statistical analysis revealed strong and moderate correlations between DHWA and HA, P3A, P3BA, LP3A, PPCA, P3G, P3F and P3T.Main limitationCadaver feet were collected from different yards and body sizes, the collection of radiographic parameters without trimming and the lack of a record of the work history of these donkeys.ConclusionThis study will assist veterinarians in evaluating the long‐toe, underrun heel conformation during hoof trimming.

Numerical investigations on roll decay of a lifeboat in calm water and waves

Lifeboat serves an important water rescue equipment. Capable of self-righting and being stable in free roll decay is crucial for a safe and efficient rescue for a lifeboat. To better understand the roll decay of lifeboat in complex environments, this work performs systematic numerical investigations on roll motion of a lifeboat in both calm water and periodic wave conditions. Investigations of lifeboat in calm water show that it is capable of self-righting with the initial heel angle equal or less than 120°. Although the initial heel angle not affects the final stable status, it has remarkable influence on the self-righting process. Lifeboat with a large initial heel angle subjects to more violent roll motion in the early stage, and thus has weaker stability. Analysis also shows that the nonlinear component of the roll damping coefficient becomes the major part of the total damping coefficient with an increasing initial heel angle. On the other hand, in waves conditions, lifeboat undergoes periodic roll motion in beam waves, and the periodic rolling motion is primarily associated with wave frequency. When the wave frequency approaches the natural frequency of the lifeboat, the rolling motion increases drastically. The present work helps to better understand the self-righting process of a lifeboat in complex environments and also to provide guidance in design and safe operation of a lifeboat.

Strategic palmar trimming before conventional shoeing shows potential for managing underrun heels in horses

Background Underrun heels are among the most hoof imbalances, causing poor performance in hoses. Several corrective shoeing protocols have been performed, but the outcomes have yet to be consistent. In this study, we proposed an alternative trimming protocol for managing underrun heels: strategic palmar trimming before conventional shoeing. Therefore, the current study aimed to investigate the potential of strategic palmar trimming before conventional shoeing for managing hoof imbalance in horses with underrun heels. Methods Eleven affected horses were divided into control (5 horses with 14 defective hooves) and experimental (6 horses with 16 defective hooves) groups. The experimental group underwent strategic palmar trimming before conventional shoeing, while the control horses received regular trimming before traditional shoeing. Dorsal hoof wall angle (DHWA)/heel angle (HA) ratios, heel-bulb distance, and six parallel lines indicating solar surface dimension were determined before, and after 5, 10, 15, 20, 25, and 30 weeks of the different trimming protocols. Palmar trimming distance was only measured in experimental horses. Results A group-by-time interaction was observed for DHWA/HA ratios and solar surface dimension. Separate effects for group and time were observed in the heel–bulb distance. A modification in hoof conformation was detected at 25-30 weeks only in horses in the experimental group, including decreases in DHWA/HA ratio, heel–bulb distance, and palmar trimming distance, coinciding with an increase in palmar width of trimmed hooves. Conclusions Different trimming protocols produced a different effect on hoof conformation. Therefore, tactical remedial trimming can potentially control poor hoof conformation in horses with underrun heels.

Correlation analysis between Pirani score and talo-navicular angle,calcaneo-cuboid angle and tibio-calcaneall angle of infant clubfoot under ultrasound

Objective: To explore the evaluation effect of ultrasonography and Pirani score on tarsal deformity, treatment effect and pseudo-correction of congenital clubfoot in infants and young children, and the correlation between the two methods. Methods: This is a retrospective case series study. The clinical data of 26 children (40 feet) with congenital clubfoot who were evaluated by ultrasonography in the Third Affiliated Hospital of Zhengzhou University from January 2020 to January 2023 were retrospectively collected. There were 16 males and 10 females. The age at the first ultrasound examination was (M(IQR)) 9.0 (18.0) days (range: 1 to 46 days). All patients were treated with Ponseti method by the same physician. The Pirani scores before and after treatment and at the last examination, and the talonavicular angle, calcaneocuboid angle and tibiocalcaneal angle measured by ultrasound were collected, and the treatment and follow-up were recorded. Paired sample t test, repeated measures analysis of variance or Kruskal-Wallis test were used for data comparison, and Spearman correlation analysis was used for correlation analysis. The receiver operating characteristic curve was used to calculate the efficacy of ultrasound in evaluating different Pirani scores. Results: The number of plaster fixation in 26 children was 4.0 (1.0) times (range: 2 to 8 times). The medial talonavicular angle and posterior tibiocalcaneal angle were significantly improved after treatment and at the last follow-up compared with those before treatment, and the differences were statistically significant (all P<0.01). There was no difference in lateral calcaneocuboid angle before and after treatment and at the last follow-up (F=1.971, P>0.05). Pseudo-correction occurred in 2 cases (2 feet) during the treatment, with an incidence of 5%. Correlation analysis showed that there was a moderate positive correlation between talonavicular angle and Pirani midfoot score (r=0.480, P<0.01). There was no correlation between calcaneocuboid angle and Pirani midfoot score (r=0.114, P=0.105). There was a moderate negative correlation between tibial heel angle and Pirani hindfoot score (r=-0.566, P<0.01). The cut-off point of Pirani midfoot score of 1.5 was 38.78°, the sensitivity was 0.90, the specificity was 0.56, and the area under the curve was 0.75. The cut-off value of angle was 27.51 °, the sensitivity was 0.16, the specificity was 0.92, and the area under the curve was 0.44.The cut-off points of Pirani midfoot score of 3.0 were 45.08°and 9.96°, the sensitivity was 0.94 and 0.91, the specificity was 0.37 and 0.42, and the area under the curve was 0.59 and 0.62, respectively. The cut-off values of Pirani hindfoot score of 2.0 and 3.0 were 167.46° and 160.15°, respectively. The sensitivity was 0.75 and 0.67, the specificity was 0.81 and 0.83, and the area under the curve was 0.78 and 0.71, respectively. Conclusion: Ultrasound can complement with Pirani score, visually and dynamically observe the morphology and position changes of talonavicular joint, calcaneocuboid joint and tibiotalocalcaneal joint, monitor the recovery and pseudo-correction of tarsal bones, and better evaluate the therapeutic effect.

Tackling Modern Sailing Challenges with a CFD-based Dynamic VPP

A dynamic Velocity Prediction Program (VPP) integrated in a Computational Fluid Dynamics (CFD) code is described. Aerodynamic forces are obtained either through empirical coefficients or interpolated from aerodynamics matrices. These aerodynamic forces are then input to the hydrodynamics CFD solver, which solves both the flow and the motions of the boat, resulting in a closely coupled VPP. For a given True Wind Angle and True Wind Speed a sail power parameter is optimised to obtain the best possible boat speed within heel angle constraints. This approach allows naval architects to swiftly and precisely compare several yacht designs in real sailing configurations using only a few CFD computations. Several advanced features recently added to this program are covered in this paper including convergence criteria, automatic grid refinement, foil fluid-structure interaction, multiple aerodynamics models and rudder control. Results obtained from our CFD VPP on a 40-feet fast-cruising yacht demonstrates promising agreement with other existing VPP polars, affirming the accuracy and reliability of our approach. The CFD VPP presented was also successfully applied to an IMOCA, a 60-feet racing yacht.

Evaluation of professional footwear and its relationships with the foot structure among clinical nurses.

Purpose: This study aimed to evaluate professional footwear comfort, functionality and style as well as their relationships with the foot structure among nurses. Methods: We examined 120 clinical nurses aged 40-50 years, occupationally active, wearing specific type of foot-wear at work for a minimum of 7 h a day, for 5 days prior to the research. The study relied on the CQ-ST podoscope for measurements of foot. Perception of footwear comfort, functionality and style scales were also used in the research. The results were analysed with the use of Mann-Whitney U-test and Spearman's rank correlation. Results: Statistically significant negative associations were found between right and left foot length and overall comfort of footwear ( p = 0.045, p = 0.045) as well as between right and left foot width and arch height ( p = 0.015, p = 0.028). Heel angle positively correlated with safety ( p = 0.008, p = 0.050), ease of donning and doffing ( p = 0.001, p = 0.004), as well as shoe style ratings ( p = 0.047). Variables determining shoe comfort were positively correlated with most shoe functionality characteristics as well as with shoe style (p < 0.05). Conclusions: Tested medical footwear meets the requirements of nurses in terms of comfort, functionality and aesthetics, and the studied features of footwear can be a useful guideline for the selection of shoes for representatives of this professional group. These footwear can be an element of workwear, and even, in the case of women with transverse flat feet - an alternative to ordinary utility shoes. There is a need to consider different widths for the same length size in medical footwear designs.

Numerical Study on the Flow Characteristics of High Attack Angle around the Submarine’s Vertical Plane

When a submarine encounters an emergency situation, it should take emergency-surfacing actions by moving upward with a large angle of attack in the vertical plane. Previous research has often neglected the effect of vertical plane motion on the lateral force (Fy), rolling moment (Mx), and yawing moment (Mz). To examine the flow characteristics of submarines at high angles of attack on the vertical plane, the SST-DDES method is adopted in conjunction with adaptive mesh refinement (AMR) technology, and the new Omega vortex detection method is employed as the AMR criterion for numerical calculations. The obtained results are then appropriately verified by conducting water tank experiments, and the effects of different angles of attack and heel angles on Fy, Mx, and Mz are methodically examined. The results reveal that, in the flow around the vertical plane of a submarine, the influence of Fy and Mz cannot be ignored. In addition, when the vertical velocity of the hull is greater than 0.6 m/s, the influence of Mx cannot be overlooked either. When the angle of attack on the vertical plane of the submarine is greater than 25°, the effects of Fy, Mx, and Mz cannot be neglected, and the effect of Mz is particularly prominent, with its amplitude close to or greater than the average value of the pitch moment (My). The obtained results reveal that the presence of the heel angle (θ) intensifies the forces on the hull for Fy, Mx, and Mz, and the forces caused by the vertical velocity at Fy, Mx, and Mz cannot be neglected. These findings can provide a mechanical analysis basis for the analysis of nonlinear motion phenomena during submarine surfacing.

Automation of vessel slamming avoidance processes

The object of the research is the processes of slamming automatic avoidance when the vessel is sailing in a storm. During stormy sailing, the vessel is subjected to external influences from wind and waves, which lead to strong dynamic loads on the hull, increase in heel and trim angles, flooding of the deck. The vessel's speed decreases, its controllability deteriorates. Slamming is one of the most dangerous phenomena in storm sailing. The appearance of slamming depends on many factors: the size and shape of the vessel's hull, the draft of the bow, the state of the sea, the vessel's course and speed. Slamming is characterized by impacts of the bow and the bottom of the vessel's hull against the water when moving towards waves, the length of which is approximately equal to the length of the vessel. Impacts are accompanied by body shaking, due to a sharp increase in the load on the bottom, and a slowly fading vibration. Hydrodynamic shocks on the bottom and general vibration are the reasons for the violation of the local and general strength of the hull. Slamming and other dangers of stormy sailing are the cause of strong psycho-emotional stress of boatmen, contribute to the accumulation of fatigue, which is a prerequisite for accidents. In the article, a method of automatic control of the vessel to prevent slamming was developed. The obtained results are explained by the use of an on-board computer, the construction of a dangerous area of slamming in on-board computer, the use of a gradient method of finding the optimal trajectory in time of the phase point output from the dangerous area, and the maintenance of the optimal trajectory by means of an automatic control system. The use of the developed method allows you to automatically avoid slamming, reduce the influence of the human factor on control processes, reduce crew fatigue, reduce the risks of losing the ship and cargo, and increase the safety of navigation. The developed method can be used on vessels, provided it is integrated into the existing automated system of the on-board computer to solve the problem of automatic avoidance of slamming during stormy sailing

Strategic palmar trimming before conventional shoeing shows potential for managing underrun heels in horses

Background: This study aimed to investigate the potential of strategic palmar trimming before conventional shoeing for managing hoof malconformation in horses with underrun heels. Methods: Eleven affected horses were divided into control (5 horses with 14 defective hooves) and experimental (6 horses with 16 defective hooves) groups. The experimental group underwent strategic palmar trimming before conventional shoeing, while the control horses received regular trimming before traditional shoeing. Dorsal hoof wall angle (DHWA)/heel angle (HA) ratios, heel-bulb distance, and six parallel lines indicating solar surface dimension were determined before, and after 5, 10, 15, 20, 25, and 30 weeks of the different farriery protocols. Palmar trimming distance was only measured in experimental horses. Results: A group-by-time interaction was observed for DHWA/HA ratios and solar surface dimension. Separate effects for group and time were observed in the heel–bulb distance. A modification in hoof conformation was detected at 25-30 weeks only in horses in the experimental group, including decreases in DHWA/HA ratio, heel–bulb distance, and palmar trimming distance, coinciding with an increase in palmar width of trimmed hooves. Conclusions: Different trimming protocols produced a different effect on hoof conformation. Therefore, tactical remedial trimming can potentially control poor hoof conformation in horses with underrun heels.

CFD-based Numerical Analysis of Amphibious Vehicle Hydrodynamics during Turning Motion

Amphibious vehicle has blunt bow and multi appendage structure, and its flow field characteristics are very complicated during maneuvering. In this paper, a simplified model of amphibious vehicle with propulsion device is established, and the thrust volume force model is introduced to consider the pumping and water jet propulsion of the water effects jet propulsion device. The technique of overlapping grid is used to deal with the six-degree-of-freedom large-scale hull motion problem, and study the turning motion of amphibious vehicle under different rudder angles. The results of numerical simulation show that the amphibious vehicle will enter a stable turning state when turning on the water surface, but the heel angle is large, the draft depth and the speed drop are significant. The state of water baffle has a significant influence on vehicle trim and roll motion. Larger vehicle pitching motion amplitude will increase the risk of overturning.

Analysis of Bahrain GP Circuit for Use in MotoGP with Account for Gyroscopic Effect of Wheels on Speed and Lean Angle

Motorcycle racing is an exhilarating and demanding sport that requires riders to master a variety of skills and techniques. Among these, counter-steering and leaning the motorcycle are paramount for achieving efficient and safe cornering. Unfortunately, a significant number of major accidents in motorcycle racing occur during the cornering phase, particularly near sharp corners on racing tracks. To mitigate these risks and ensure rider safety, this research project focuses on the dynamic analysis of the gyroscopic couple effect on motorcycle wheels with the aim of determining the safe angle of heel for more efficient and secure cornering.

Immediate Effect of Hoof Trimming on Hoof and Thoracic Joint Angles in Mangalarga Mares.

It is important to understand the effects of hoof trimming on hoof and limb conformation to maximize its benefits on the health of the appendicular skeleton of horses, thus promoting improvements in athletic performance and sporting longevity with regard to athletic horses. There is little information on possible changes in the angulation of the thoracic limb joints after hoof trimming and correlations between the angulation of the thoracic limb joints with hoof measurements. To that purpose, nineteen Mangalarga mares received routine hoof trimming. Visual recordings (photographs) were taken before and after the procedure. Differences (p < 0.05) were found in hoof length, toe angle, heel angle, medial heel height, and metacarpophalangeal angle. Before trimming, correlations were found between frog length and scapulohumeral angle (SH) (r = -0.457; p = 0.049), and between toe length and shoulder-ground angle (SG) (r = -0.553; p = 0.049). A correlation was also seen between the distance from the frog to the lateral wall and the SH angle (r = 0.690; p = 0.001). After trimming, there was a correlation between humeroradial (HR) and SH joint angles (r = 0.669; p = 0.002), and the SG and SH angles (r = 0.488; p = 0.034). This study showed an immediate effect of trimming on the toe angle and heel angle and on the metacarpophalangeal joint angle, in addition to correlations between the hoof and proximal joint angles, following trimming, thus evidencing the relevance of trimming not only in hoof morphology, but also in the conformation of the appendicular skeleton of horses.

The frequency of significant relationships of selected features describing feet with the torso features among youth aged 7-13

Introduction. Research on the relationships and co-occurrence of the feet and torso features in a group of 4-6-year-old children showed that the values of the left foot features show a significantly more frequent relationship with the features of the torso than the right foot features. Material and method. The research was carried out in the group of adolescents aged 7 to 13 and registered 12,898 observations of the value of 90 features describing torso and feet. The working stand for measuring the features of body posture and feet using the photogrammetric method consists of a computer and a card, a programme, a monitor, a printer, and a projection-receiving device with a camera for measuring selected features. Conclusions A similar number of features of the right and left foot is often associated with the torso features. The following features like width of the feet, the angle of the 5thhallux valgus and the left foot big toe, the heel angle and height of the right foot second arch, the height of the second longitudinal arch and the length of the left foot, and the length of the first arch of the right foot show especially frequent relationships. The feet features show the most frequent significant relationship with the torso features of the frontal plane, whereas less of sagittal plane and occasionally of transversal plane. Torso features, which the most common features of the feet are significantly related to are the height and length of lumbar lordosis, the height of thoracic kyphosis, the angle of the torso flexion in the sagittal plane, the length of the thoracic kyphosis, the bent angle of the thoracic-lumbar spine, the depth of thoracic kyphosis, the depth of lumbar lordosis, and the inclination angle of the upper thoracic segment of the spine. The features of the feet are whereby most frequently related to the features of lumbar lordosis.

Experimental characterization on slamming loads of a truncated ship bow under asymmetrical impact

Due to the complex three-dimensional flows such as fluid separation, fluid breaking and bubble flows, accurate prediction of slamming loads on 3D ship bow is still limited. In this paper, the asymmetrical slamming load characteristics of a truncated ship bow under the combination of heel and pitch postures are clarified through drop experiment. An angle device designed in the experiment has effectively adjusted the heel and pitch posture of the test model independently. The study provides a complete dataset (water entry velocity and pressure), which provides reference for future numerical verifications. Load characteristics of bow impact under asymmetrical water entry attitudes are analysed. The results show that some air cavity and jet flows are easy to cause the multiple pressure peaks, and affect the pressure oscillation. The influence of heel and pitch angles on impact pressure is further discussed. Finally, load characteristics with different water entry velocities are discussed to further improve its application. Results find that some abnormal pressure characteristics appear in some locations, that is, the pressure decreases with the increment of water entry velocity. The research results are expected to lay a foundation for further improving the predicting accuracy of hull slamming loads.

Effects of Rearfoot Eversion on Foot Plantar Pressure and Spatiotemporal Gait Parameters in Adolescent Athletes

Background: Foot malalignment can augment the risk of lower-extremity injuries and lead to musculoskeletal disorders. This study aimed to clarify the contribution of rearfoot alignment to plantar pressure distribution and spatiotemporal parameters during gait in healthy adolescent athletes. Methods: This retrospective study included 39 adolescent athletes who were divided into the rearfoot eversion and control groups according to a leg heel angle of 7°. A total of 78 legs were analyzed (45 and 33 legs in the rearfoot eversion [women, 53.3%] and control groups [women, 48.5%], respectively). Gait was assessed using an in-shoe plantar pressure measuring system and a wearable inertial sensor. Results: The foot plantar pressure distribution in the hallux was higher in the rearfoot eversion group than that in the control group (p = 0.034). Spatiotemporal parameters showed that the foot pitch angle at heel strike was significantly larger in the rearfoot eversion group than that in the control group (24.5° vs. 21.7°; p = 0.015). Total sagittal range of motion of the ankle during the stance phase of gait was significantly larger in the rearfoot eversion group than that in the control group (102.5 ± 7.1° vs. 95.6 ± 15.8°; p = 0.020). Logistic regression analysis revealed that plantar pressure at the hallux and medial heel and foot pitch angle at heel strike were significantly associated with rearfoot eversion. Conclusions: Our findings suggest that rearfoot eversion affects the gait patterns of adolescent athletes. Notably, leg heel angle assessment, which is a simple and quick procedure, should be considered as an alternative screening tool for estimating plantar pressure and spatiotemporal gait parameters to prevent sports-related and overuse injuries in adolescent athletes.