Pressure Distribution Research Articles

Numerical Investigation of Large Vehicle Aerodynamics Under the Influence of Crosswind

This paper presents a numerical analysis aimed at estimating the impact of crosswinds on the aerodynamics of large vehicles using ANSYS Fluid Flow and Static Structural, offering insights into the qualitative behaviour of trucks under typical traffic conditions. The cases analysed focus on airflow distribution when a truck, traveling at approximately 100 km/h, passes under a portal while exposed to varying crosswind intensities: weak, moderate, and strong lateral winds. A detailed examination of the truck and portal reveals significant interactions between the induced airflow patterns, affecting truck handling and stability. This is evidenced by shifts in velocity and pressure distributions, changes in drag coefficients, and variations in turbulent kinetic energy, all of which are analysed and discussed in this study.

Comparison of static balance and pressure distribution in individuals with unilateral lower limb amputation: The role of barefoot, heel support, and vision

Background: In some cultures, shoes are not worn indoors. Prosthesis use barefoot can lead to pressure injuries and loss of balance due to abnormal residual limb loading. Objective: This study aimed to compare the effect of wearing standard alignment prostheses using barefoot at home and visual alteration on static balance and pressure distribution in individuals with unilateral transfemoral amputations (TFAs) or transtibial amputations (TTAs). Study design: Prospective parallel experimental study. Methods: Participants with unilateral TTAs (n = 44) and TFAs (n = 37) were included. Balance and load distribution were assessed using MatScan pressure platforms, both with a heel (3 × 2 cm2 area; 1.8 cm height) support (the use of shoes with a heel is mimicked) and barefoot. Results: Balance parameters were disrupted in all groups when eyes closed position (p < 0.05). Using heels reduced anterior-posterior and medial-lateral sway in TTA group during eyes closed (p < 0.05). When standing barefoot with the eye open position, TFA group had more load on the rear foot of the prosthetic foot and less load on the forefoot than TTA group (p < 0.05). The opposite pattern was observed in the intact foot (p < 0.05). Using heels in TTA group increased the load on the front of the intact side and the rear of the prosthetic side (p < 0.05). Conclusion: The balance parameters were impaired in both groups while standing barefoot in the absence of vision. However, using heel supports improved static balance in the TTA but not in the TFA group. Using heel support changed this load distribution in both groups, especially in the TTAs, and created positive changes.

The effect of full-body weight-bearing on palmar pressure distribution in collegiate-level gymnasts

ABSTRACT Wrist and hand biomechanics under full-body load are not fully understood. To identify potential anatomy-related differences in hand loading, 15 former collegiate athletes completed a 45-second handstand on a novel emed® pressure platform system. Center of pressure (CoP) and force distribution across the palmar surface were analysed during the stabilised phase. Maximum force, mean pressure, and contact area were calculated in four palmar anatomic subregions: hypothenar, thenar, metacarpals, and fingers. These values were related to ulnar variance measurements obtained from a participant handstand hold in a weight-bearing computed tomography machine. About 93% of participants shifted their CoP towards their dominant hand (p < 0.001), and among all participants, the dominant hand applied an average of 8.91% (p = 0.002) higher maximum force than the nondominant hand. The proportion of total mean force was highest in the hypothenar (47.1%) and thenar regions (36.5%). Every 1.00 mm increase in ulnar variance corresponded to a 2.8% increase in maximum force in the hypothenar region (p = 0.037). This investigation emphasises the role of gymnastics hand dominance on left/right hand weight distribution and the importance of the hypothenar zone in distributing pressure during handstands. It also indicates that force transmission through the wrist to the palm is contingent on radioulnar positioning.

Theoretical model construction and static performance analysis of multi-leaf journal foil bearings

Abstract Multi-leaf journal foil bearing (MLJFB) structures are complex, making performance prediction challenging, and the accurate prediction of gas film thickness and pressure distributions is crucial. In this study, COMSOL finite-element software was used to establish an initial foil assembly and structural deformation simulation model for an MLJFB with bump foils. Using MATLAB, a compressible gas lubrication model was established and solved using the finite volume method (FVM). Real-time data transfer between COMSOL and MATLAB enabled a fully coupled fluid-structure interaction simulation. This model meticulously accounts for the pre-tension force in the multi-leaf bearing assembly, contact friction between adjacent foils, and the interaction between the top foil and gas film pressure. The effects of journal movement distance, direction, and top foil overlapping ratio on the bearing capacity as well as the effects of different external load directions on the journal equilibrium position were analyzed based on this model. The results indicate that increasing the top foil overlapping ratio enhances the bearing capacity of the MLJFB. Furthermore, compared to the direction of the top foil overlap position, external loads applied in the direction of the top foil midpoint are more beneficial for bearing operational stability.

The research on the applicability of different typhoon wind fields in the simulation of typhoon waves in China’s coastal waters

Typhoon waves possess significant destructive potential, and their numerical simulation relies on accurate sea surface wind fields. An evaluation of different combinations of the radial air pressure distribution coefficient B and the radius of maximum wind speed (Rmax) in the Holland wind field (HWF) model was conducted to determine the optimal configuration. The HWF and the ERA5 wind field (EWF) were used as input wind fields to drive the typhoon wave model for China’s coastal waters. Validation results indicated that neither wind field accurately reflected real conditions; therefore, a hybrid wind field (HBWF) was created by combining HWF and EWF using weighting coefficients that vary with the radius of wind speed to enhance accuracy. Simulation results showed that the HBWF improved the accuracy of significant wave heights (SWHs), with a mean relative error of 25.29%, compared to 32.48% for HWF and 27.94% for EWF. Additionally, HBWF also demonstrated the best performance in terms of root mean square error (RMSE) and consistency index. Overall, the HBWF enhances the simulation accuracy of typhoon waves in China's coastal waters.

Noise generation and contribution of a single-gap bridge expansion joint: An experimental and numerical study

Noise generated from bridge expansion joints during vehicle passing has caused localized environmental problems around the world. The purpose of this paper is to investigate the vibration and noise radiation from the single-gap expansion joint induced by passing vehicles. First, a vibration and noise field test was performed for single-gap expansion joints in the highway ramps. Based on the tested results, two numerical models, involving a 3D tire-bridge expansion joint hybrid finite element model for the vibration analysis, as well as an acoustic boundary element model for the prediction of the noise radiation, were established and validated. The results of the numerical simulations and the field tests are well matched, which offers opportunities to predict the vibration and noise induced by vehicles passing through using the proposed methodology. Finally, the acoustic contribution and sound pressure distribution of different sound sources were discussed. The research showed that, for the single-gap expansion joint, the contribution of tire noise to the total noise level is dominant, and the contribution of structure-borne noise of the expansion joint and girder to the total noise level is insignificant. The findings emphasize the importance of tire noise and provide new ideas for noise control of single-gap expansion joints.

Harnessing Foot Mechanics: The Role of Lacing Techniques in Enhancing Comfort and Reducing Injury Risk

Background: Lacing techniques are often viewed as a functional necessity, but recent research has highlighted their role as a customization tool for foot health and comfort. This review synthesizes findings from studies examining the biomechanical effects of different lacing patterns on pressure distribution, tendon loading, and foot mechanics. Methods: We analyzed studies that investigated various lacing techniques, including tightness and patterns. Objective measurements, such as pressure insoles and cadaveric models, were used to quantify the effects. Diverse study populations, including individuals with foot health concerns and athletes, were considered. This study was conducted as a scoping review following the JBI methodology, adhering to the PRISMA-ScR guidelines. Results: The studies collectively reveal that lacing patterns significantly influence dorsal pressure distribution during activities like running. Customized lacing can optimize foot biomechanics, reducing the risk of injuries related to abnormal pressure distribution. A total of 27 records were identified from the initial search. After removing duplicates and screening, four articles were included in the final review. Additionally, certain lacing configurations were found to reduce peak Achilles tendon tension, a crucial finding for injury-prone individuals. Conclusions: Proper lacing techniques are not just a functional aspect but a means to enhance foot health and prevent injuries. Healthcare professionals can provide personalized lacing recommendations to patients, with implications for those with specific foot conditions, athletes, and individuals at risk of injuries. The importance of patient education on the significance of lacing techniques cannot be overstated, emphasizing the need for informed choices when lacing shoes. These findings underscore the multifaceted role of lacing techniques in promoting foot health and well-being.

CFD-FEM Analysis for Functionality Prediction of Multi-Gear Pumps

A comprehensive model for evaluating the functionality of a multi-gear pump has been developed. The integrated model for assessing the functionality of a multi-gear pump contains a computational fluid dynamics analysis (CFD) model combined with a finite element method (FEM)-based strength model. Two submodels were linked: a CFD submodel to evaluate the internal pressure distribution of the pump and a structural FEM submodel to calculate the stresses and structural displacements of the pump due to fluid pressure. Finite element analysis in SolidWorks 2016 was used to evaluate the strength of the gear joints of the pump gears. As the pressure of the working fluid increases from 6 to 20 MPa, a linear increase in Mises stresses is observed. At the shaft, these stresses increase to 226.2 MPa, and at the tooth mouths, they reach a maximum value of 205.5 MPa. With the increase in torque on the drive shaft from 100 to 500 N·m, there is a significant increase in Mises stresses localized in the contact zones of the shaft with the drive gear. Analysis of the data obtained showed that the displacements caused by the pressure of the working fluid are insignificant compared to the displacements arising under the action of torque. With increasing pressure and torque, there is a tendency to decrease the safety factor, which indicates a decrease in the safety factor of the design of the multi-gear pump. The safety factor is not provided at a torque of 400–500 N·m. The simulation results are confirmed by correlation analysis. The average approximation error is 5–7%.

AI‐Enhanced Gait Analysis Insole with Self‐Powered Triboelectric Sensors for Flatfoot Condition Detection

AbstractFlatfoot is an orthopedic malformation where the inner foot arch flattens during motion, potentially leading to chronic musculoskeletal issues. Monitoring foot conditions is essential, as existing screening methods often need more objectivity and cost‐effectiveness. This research develops an insole‐based screening device using self‐powered triboelectric nanogenerators (TENGs) as tactile sensors and Arduino hardware setup. TENG converts mechanical energy into electrical energy, offering simple fabrication, cost‐effectiveness, longevity, and high‐output power benefits. The device records the electrical output generated by foot movements via Arduino and sends data via Bluetooth to the processing tool. Machine learning algorithms employing the Random Forest Classifier process the data to detect flatfoot conditions accurately after training sessions. For data collection, 100 participants are asked to march and walk for the same duration and distance, ensuring consistent output. Analysis reveals that the insoles' middle sensors produce higher electricity levels in individuals with flatfoot, showing a uniform pressure distribution across the foot and contact in the arch area. In contrast, individuals with normal feet exert more pressure on the toe and heel foot areas. The system achieves an overall accuracy of 82%, demonstrating the insole's potential as a commercial flatfoot detection device.

Calendering of non-isothermal viscoelastic sheets of finite thickness: A theoretical study

Abstract In this article, the sheeting of pseudoplastic material under non-isothermal conditions has been studied. It is an excellent forecasting instrument for sheeting, where the thickness of the sheet is relatively thin in relation to the roll size, according to theoretical study based on the lubrication theory. At the calendering process, the detachment point is determined by taking the material parameter’s impact into account. The governing equations are derived for the constitutive equation of the Carreau fluid with momentum and energy equations. Suitable non-dimensional parameters are used to develop the non-linear partial differential expressions into ordinary differential systems. The maximum pressure, roll separating force, normal stress effect, and power delivered to the fluid by rolls are among the engineering-relevant quantities that are determined. Moreover, a graphic analysis is conducted to examine the impact of different material parameters on the temperature profile, pressure gradient, velocity profile, and pressure distribution. The results specific mechanism is explained in depth.

Design of a custom metamaterial insert for improved pressure distribution within transtibial prosthetic sockets.

Uneven pressure distribution within a transtibial prosthetic socket can lead to discomfort, skin degradation, and suspended prosthesis use. Current custom interfaces to improve pressure distribution are often costly, time-intensive to fabricate, or cannot be incorporated into standard socket fabrication methods. In this technical note, we describe the design and preliminary clinical evaluation of a novel transtibial prosthetic socket insert with modifiable mechanical properties, which can be incorporated into the current clinical cycle of care. The custom insert (termed "inlay") relies on a triangular unit cell, which can be modified based on the desired stiffness profile. Inserts are 3D printed in a soft polymer material and inset into shape-matched voids in a socket creating regions of custom offloading. Preliminary clinical efficacy of the inserts was assessed in a pilot long-term cross-over evaluation. After Institutional Review Board approval, 3 pilot participants wore a shape-matched replica of their habitual socket modified for insert use and a shape-matched socket without. Sockets were worn for 4-week each, and inner socket pressures were measured with thin film pressure sensors at the end of the wear period. Peak pressures within the distal tibial region of interest were decreased for 2 of 3 participants during midstance of level-ground walking when wearing the socket with inlays. The technical methods and results presented provide a new method to address high pressure regions within a transtibial prosthetic socket. The 3D-printed inlays can be rapidly produced allowing for easy modification and replacement without require new socket fabrication.

Accelerating Numerical Simulations of CO2 Geological Storage in Deep Saline Aquifers via Machine-Learning-Driven Grid Block Classification

The accurate prediction of pressure and saturation distribution during the simulation of CO2 injection into saline aquifers is essential for the successful implementation of carbon sequestration projects. Traditional numerical simulations, while reliable, are computationally expensive. Machine learning (ML) has emerged as a promising tool to accelerate these simulations; however, challenges remain in effectively capturing complex reservoir dynamics, particularly in regions experiencing rapid changes in pressure and saturation. This article addresses the challenges by introducing a fully automated, data-driven ML classifier that distinguishes between regions of fast and slow variation within the reservoir. Firstly, we demonstrate the variability in pressure across different reservoir grid blocks using a simple brine injection and production scenario, highlighting the limitations of conventional acceleration approaches. Subsequently, the proposed methodology leverages ML proxies to rapidly and accurately predict the behavior of slow-varying regions in CO2 injection simulations, while traditional iterative methods are reserved for fast-varying areas. The results show that this hybrid approach significantly reduces the computational load without compromising on accuracy. This provides a more efficient and scalable solution for modeling CO2 storage in saline aquifers.

Experimental study on the aerodynamic characteristics and wake flow feature of triangular prisms with various round corner radius

In this work, particle image velocimetry (PIV) and wind pressure measurements are employed in the wind tunnel to investigate triangular prisms with different rounded corner radius. The effect of rounded corner radius on wind pressure distribution, aerodynamic force, and wake flow characteristics are analyzed. Results indicate that the surface wind pressure can be effectively reduced through filleting treatment, with an average drag coefficient decrease of 52.7% as the corner shape transitions from sharp to round. The continuous increase of the radius of the rounded corner causes an accretion of the fluctuating lift coefficient, and a slow decrease of the drag coefficient. The modification of the corner radius has a limited impact on the vortex shedding frequency, but the shedding vortex tend to gather the leeward side. Additionally, statistical analysis of wake flow shows that an increment in the rounded corner radius leads to a significant reduction in the wake recirculation region, amounting to 20.16%. Concurrently, the peak values of turbulent kinetic energy and Reynolds stress exhibit a pattern of initial increase followed by a decrease. On the other hand, results of proper orthogonal decomposition suggest that the spatial distribution of vortex structures becomes increasingly compact with the enlargement of the rounded corner radius.

Finite-element simulation of functional knee sleeves based on three-dimensional modeling of the knee joint

Knee sleeves are one of the most satisfying and widely used items of protective equipment for sports enthusiasts. Achieving an effective balance between functionality and comfort is a key factor in the design of knee sleeves. However, there are still some problems with the knee protection products currently on the market, such as poor thermal and moisture comfort, difficulty in putting on and taking off, slippage during doing sports, and the lack of a timely and effective feedback mechanism that cannot guide the user to actively adjust their movement posture to avoid sports injuries. To improve the function and pressure comfort of the human body after wearing knee sleeves, this study took the knee joint as the research object, established a three-dimensional knee joint model through computed tomography (CT) scanning and Mimics software, and then built a finite-element model under the contact state between the human body and pressure clothing on this basis. Moreover, ABAQUS was used for finite-element simulation to obtain the pressure and displacement distribution of knee joints after wearing knee sleeves. In order to further investigate the stress state and deformation trend of knee joint after wearing knee sleeves, each section of the human body at the knee joint was divided into four regions according to the angle, and the functional relationship between pressure and displacement was obtained by curve fitting. This study has significance for the investigation of the pressure comfort threshold of knee sleeves and the optimization of the design of functional knee sleeves.

Experimental Study of Airfoil Aerodynamic Behavior under Oscillating Motion in Ground Effect

When a flying vehicle approaches a water or land surface, it induces changes in the fluid flow field pattern known as the "ground effect." This research analyzes the ground effect phenomenon, exploring its impact on aerodynamic coefficients and flow patterns around the NACA0012 airfoil in an incompressible subsonic regime under static and dynamic conditions with pitch movements. Numerical simulations and experimental testing in an incompressible subsonic wind tunnel were deployed. The flow field solution is derived from the Navier-Stokes equations, incorporating the Transition SST turbulence model. Initially, the impact of the ground effect phenomenon was investigated at varying distances from the surface in the static state. Subsequently, the airfoil underwent a sinusoidal pitching oscillation at each distance with a specified frequency and amplitude. This allowed for examining its aerodynamic characteristics over time. The static analysis results reveal alterations in the curve's behavior and pressure distribution on the airfoil surface at close distances to the surface. This is attributed to the ground effect phenomenon, which reduces lift force to a certain height and then increases. Dynamic analysis further demonstrates changes in lift coefficient oscillation amplitude. It also exhibits a minimum and maximum lift point phase difference as the airfoil approaches the surface.

Non-Gaussian properties and their effects on extreme wind pressure of a 4:1 rectangular cylinder

This paper investigates the wind pressure characteristics of a 4:1 rectangular cylinder under 19 wind angles using a rigid model wind tunnel test, focusing on non-Gaussian properties and extreme wind pressure. The wind angle (α) varies from 0° to 90° and the Reynolds number (Re) ranges from 0.32 × 105 to 2.14 × 105. The spatial and statistical distributions of wind pressure, along with its non-Gaussian properties, are presented. Detailed analyses of these characteristics are provided. The peak factor of wind pressure was calculated using the modified Hermite method. The results indicate that the skewness and kurtosis of the windward region of the 4:1 rectangular cylinder remain relatively unchanged with varying wind angles. In contrast, the skewness and kurtosis in the separation and wake zones are significantly influenced by changes in the wind angle. Most wind pressures on the 4:1 rectangular cylinder exhibit negative bias and a softening process. The non-Gaussian properties are most prominent at the corner of the wake zone. The peak factor of 2.5 (used in Chinese code) or peak factor g,G based on Gaussian processes on the separation and wake zones of interest are much smaller than the peak factors g,NG calculated based on the modified Hermite method. Ignoring non-Gaussian properties underestimates extreme wind pressures by at least 20%–30%. Therefore, non-Gaussian properties must be considered when calculating wind pressure extremes for similar rectangular structures. Additionally, the peak factor value in the Chinese code should be increased appropriately to ensure structural safety.

3D thermodynamics and parameters analysis of the external combustion hot blast stove

The external combustion hot blast stove is widely used in the steelmaking industry due to the advantage of providing a large amount of high-temperature and stable hot blast for blast furnaces. To research the thermal efficiency and stability of external combustion hot blast stoves, the non-equilibrium porous medium model coupled with transient thermal analysis is used to discuss the characteristics of two types of external combustion hot blast stoves during the cyclic operation process. In this paper, a comparison of the numerical data and in situ data during one cycle to ensure the accuracy of the calculation, which of the results showed that the temperature maximum relative error value is within 3%. The numerical results displayed that the velocity and temperature distribution of fluid are mainly affected by pressure, flow rate, cycle time, and geometric structure, where the hot blast temperature is affected by the cycle time but the distribution of velocity and relative pressure are affected by the height of hot blast branch. It can be concluded that the flow field and the structure of type A hot blast stove are more stable than that of type B by comparing the results of two types of hot blast stoves.

Solar Plasma Noise in TianQin Laser Propagation: An Extreme Case and Statistical Analysis

Abstract TianQin (TQ) proposes to detect gravitational-wave signals by using laser interferometry. However, the laser propagation effect introduces a potential noise factor for TQ. In this work, we used magnetohydrodynamic (MHD) simulations to obtain the space magnetic field and plasma distributions during an extremely strong solar eruption, and based on the MHD simulation result, we investigated laser propagation noise for TQ. For the extremely strong solar eruption event, we find that the laser propagation noise closely approaches 100% of TQ’s displacement noise requirement for the Michelson combination, while the laser propagation noise is still about 30% of TQ’s displacement noise requirement for time-delay interferometry (TDI)-X combination. In addition, we investigate the laser propagation noise for 12 cases with different solar wind conditions. Our finding reveals a linear correlation between the laser propagation noise and several space weather parameters, e.g., solar wind dynamic pressure, Sym-H, and Dst, where the correlation coefficients for solar wind dynamic pressure are strongest. Combining the cumulative distribution of solar wind dynamic pressure from 1999 to 2021 with the linear correlation between solar wind dynamic pressure and laser propagation noise, we have determined that the occurrence rate of the laser propagation noise to be greater than 30% of TQ’s displacement noise requirement for the Michelson combination over the entire solar activity week is about 15%. In addition, we find that TDI can suppress the laser propagation noise, and reduce the occurrence rate of the laser propagation noise exceeding 30% of TQ’s requirement to less than 1%.

Mode decomposition to identify oscillation patterns of flexible aeroshell

Flexible aeroshells, featuring deformable membrane surfaces supported by pressurized gas, offer a novel re-entry system for high-altitude deceleration during re-entry. The flexibility of structural components introduces unique challenges in predicting aerodynamic behavior, as deformations can significantly alter the flow field, affecting pressure distribution and potentially causing aerodynamic instabilities. Therefore, coupled analysis is crucial to ensure the performance reliability of inflatable aeroshells. This study investigates the unsteady aerodynamic behavior, considering structural deformation in a two-way partitioned coupled manner in transonic flow. The dominant deformation patterns are identified using dynamic mode decomposition and the greedy compressive sensing algorithm. The findings reveal that the primary deformation pattern combines axial deformation and swing oscillation. The dominant oscillation frequencies remain different from the eigenfrequencies, indicating that the aerodynamic force is the primary driving force of such oscillations. The time evolution of these dominant modes indicates purely oscillatory behavior rather than increasing or decreasing trends. These insights are critical for the design and reliability assessment of inflatable aeroshells in varying aerodynamic environments.

Paradoxıcal effect of body mass index ranges on pedobarographic evaluatıon

Although there is evidence suggesting that obesity alters plantar pressure distribution, the specific effects of certain body mass index (BMI) ranges on pedobarographic measures in healty individuals has been poorly investigated. A cross-sectional study with 167 healthy participants was conducted to assess plantar pressure changes across 4 BMI ranges: Under/normal weight (NW), overweight (OW), obese (OB), severe obese (SO). Subjects walked on the Footscan® pressure plate at a self-selected speed, and peak plantar pressure (PPP), load rate, and contact area values were recorded. The foot was divided into 10 zones: hallux (T1), toes 2–5 (T2-5), metatarsals 1–5 (M1-M5), midfoot (MF), medial hindfoot (MH) and lateral hindfoot (LH). PPP underneath M2-M4 was lowest in the NW group (p = 0.011), and although PPP values for the SO group were lower than those for the OW and OB groups, these differences were not statistically significant. Load rate values of M2-M3 were lower in both the NW and SO groups (p = 0.008) compared to the OW and OB groups. In addition, the metatarsal load rate values for the SO group were generally lower than those for the NW group. The total metatarsal contact area of both the NW and SO groups was lower (p = 0.019) than that of the OW and OB groups in both feet. These findings suggest that as BMI increases, PPP, load rate, and contact area in the middle metatarsal region initially increase, stabilize early in obesity, and then decrease at advanced stages, indicating a shift of the load to the midfoot.