Spatial Velocity Variations Research Articles

On the relationship between the uppermost mantle (≤220 km) seismic velocity, crustal thickness, and topography in Tibet

We propose that the mantle lithospheric density and crustal thickness are correlated in such a way as to produce a flat Tibetan Plateau. We observe that the mantle lithosphere is relatively uniform beneath the Himalaya and southern and central Tibet, despite a near doubling of crustal thickness relative to India. Farther north, cratonic mantle lithosphere disappears over large regions of north-central Tibet, giving rise to large lateral variations in uppermost mantle Vs anomalies (>12%) that are uncorrelated with changes in surface elevation but are closely related to changes in crustal thickness. This decoupling of surface topography from spatial variations in upper mantle seismic velocity, and assumed buoyancy, implies that Tibetan topography is controlled by a crust-mantle interaction that is able to maintain its near constant elevation. This crust-mantle interaction is likely driven by gravitational potential energy with a very weak crust. Magmatism, with ages of ca. 20 Ma to Present, spatially correlated with this region with no sub-Moho mantle lithosphere implies destabilization of mantle lithosphere in northern Tibet. Cratonic Indian underthrusting for the past 25 m.y. has also not led to significant topography in the plateau through time. The magmatism may have helped weaken the crust, allowing it to respond to changes in uppermost mantle buoyancy, resulting in a flat plateau.

Submerged rigid vegetation effects on flow hydrodynamics within the pool morphology

AbstractThis research is centered on a comprehensive investigation into the impact of turbulence on the movement and dispersion of materials within a three‐dimensional (3D) bedform, specifically when there is a continuous presence of rigid vegetation submerged in the flow. To achieve our research objectives, we conducted extensive velocity measurements within a channel featuring this submerged vegetation. The measurements were carried out using an Acoustic Doppler Velocimeter (ADV). Additionally, our study delved into the intricate structures and turbulent characteristics of the flow, considering the coexistence of submerged vegetation and a 3D gravel pool. This pool featured entrance and exit slopes measuring 3 and 2.5°, respectively. Our experimental setup took place in a straight flume, measuring 14 m in length, 0.9 m in width, and 0.6 m in depth. The flume was equipped with transparent side walls to facilitate observations. Furthermore, our investigation extended to the spatial variations in velocity and turbulence distributions. We analyzed various parameters including turbulence kinetic energy, integral turbulence lengths, dispersion coefficients, and advective transport. The results revealed that integral length scales offer key insights into turbulent eddy behavior. In the presence of vegetation and a 3D bedform, turbulent eddies undergo notable changes, flattening in the longitudinal direction and expanding in the transverse and vertical directions. Moreover, longitudinal advection is notably higher compared to flows without vegetation in a uniform flow or bare channel, especially for z/H > 0.2. This indicates that the presence of vegetation and a 3D bedform leads to an increase in turbulent kinetic energy (k values) that surpasses the reduction in the time‐averaged velocity component (“U”) in the U × k term, thereby enhancing longitudinal advection.

Influence of inertial and centrifugal forces on rate and flow patterns in natural fracture networks

Fluid production from fractured rock masses readily induces fracture flow velocities of meters per second. Yet, most discrete fracture flow models treat flow as laminar creeping flow or account for inertia effects only by single-fracture constitutive relationships.This numeric simulation study investigates water flow patterns and spatial velocity variations in a natural fracture network with mm-wide open fractures, studying the transition from laminar creeping to turbulent flow. After verification with a fracture intersection model, a Reynolds-time-averaged Navier Stokes solver serves to analyse flow regimes and velocity distribution. Our results show that for fracture flow velocities greater than ∼1-cm/s, fluid inertia begins to markedly alter flow patterns and the overall velocity distribution in the network. The pressure-gradient-flow relationship therefore becomes non-linear long before the flow in straight fractures enters the weak inertia regime. This prominence of inertia effects highlights the need to improve fracture network flow models.

Numerical investigation of the restored oyster reef flow field with the lattice Boltzmann method

Oyster reefs play a dual role in the ecological and economic sustainability of global estuarine resources. Due to human activity and climate change, the prevalence of cosmopolitan oyster reefs has noticeably declined in recent decades, triggering a global restoration movement. However, the hydrodynamic functions of oyster reefs during and after restoration, particularly the impacts of growth and morphology on the flow field, remain poorly understood. This study employs the lattice Boltzmann method coupled with large-eddy simulation to simulate unidirectional flow around restored oyster reef models using the open-source Palabos library. It examines the effects of unidirectional flow velocity and reef morphology on hydrodynamic characteristics. The research analyzes spatial and temporal variations in velocity, vorticity, and turbulence structure around the reef. The findings indicated significant flow field differences between the initially restored reefs and those post-restoration. The dimensionless wake region scale parameters of the initially restored reefs exhibit hysteresis effects, generating larger turbulence during the post-recruitment stage than in the initial stage. Areas of high turbulence in the wake are associated with above-canopy flow, bypass flow, and within-canopy flow. The presence of gaps and branches in the reef leads to complex turbulence structures and irregular vortex shedding in the reef's wake at the post-recruitment stage. These results are valuable for assessing oyster reef resilience and planning effective restoration interventions.

On the logarithmic nature of axial dispersion in Darcy flow through heterogeneous porous media

The present study provides novel insights in how spatial velocity variations in a heterogeneous porous medium cause the dispersion of a passive tracer. The study consists of two parts. The first part describes a series of numerical computations of the axial dispersion in the flow through heterogeneous porous media, idealized as Darcy flow through two-dimensional and three-dimensional patchwork geometries of zones with randomized permeability fields. Data on the axial dispersion were obtained using the mean age theory, which transforms the transient advection–diffusion equation into the steady-state mean age field equation, thus reducing the required computational effort by multiple orders of magnitude. This allowed to consider a sufficiently large number of randomizations to obtain a statistically representative ensemble average, as well as to consider sufficiently large systems to reduce the influence of boundary conditions. In the second part, it is shown that the relation between the axial dispersion coefficient and the velocity can be represented as a series, summing up the effect of velocity differences on all length scales, assuming the velocity differences are analogous to white noise. The sum can be closely fitted by a logarithmic law containing only two parameters with a well-defined physical meaning. A similar logarithmic dependency was also obtained by Saffman, Koch, and Brady. However, the logarithmic dependency obtained in the present work emerges from the heterogeneity of the porous medium, whereas the logarithmic dependency in the aforementioned works emerged from the no-slip boundary conditions at solid surfaces.

Spatial variation of crustal seismic velocity and Poisson’s ratio in the Jiangsu-South Yellow Sea area: Implication for seismotectonics

Spatial variation of crustal seismic velocity and Poisson’s ratio in the Jiangsu-South Yellow Sea area: Implication for seismotectonics

Clustered erosional submarine furrows at the Blake Outer Ridge on the U.S. Atlantic margin: implications for spatial variations of the Deep Western Boundary Current velocity

Clustered erosional submarine furrows at the Blake Outer Ridge on the U.S. Atlantic margin: implications for spatial variations of the Deep Western Boundary Current velocity

EFFECT OF NOZZLE CONFIGURATION ON PERFORMANCE OF A SPRAY DRYER

In this work, hydrodynamics and drying characteristics of spray dryer is numerically investigated using computational fluid dynamics (CFD) using Euler-Lagrangian (EL) approach. The gas phase is modelled as the continuous phase and solid particle as the dispersed phase. The turbulence in the gas phase is predicted using RNG version of k-ε model. As air flow pattern influences the time spent by particle in drying chamber, the spatial variation of air velocity and its circulation rate is quantified. Accordingly, optimum conditions for drying the feed slurry are determined. Further, five different outlet pipe locations are chosen and the optimum location is identified which supports the highest evaporation rate. To improve the product quality, conventional nozzle is modified and particle impact positions are analyzed. The particles impact positions on the dryer’s surface are found to be minimum for the proposed nozzle configuration and it improves the final product quality.

Influence of the spatial variation of upstream velocity on a vertical-axis tidal turbine performance

Assessment of the upstream flow available to the tidal energy converters (TEC) is key to evaluate its performance. Simultaneously, TEC technology has been innovating on its concepts and designs to expand the potential sites to harvest energy generated by tidal currents and rivers. The Gkinetic CEFA 12 is an easy-to-deploy device suitable to operate on estuary environments. The design consists of two 1.2 m vertical axis turbines attached to the sides of a buoyant platform, which uses a bluff body to accelerate the incoming flow to the rotors. The device was deployed on a single point mooring enabling passive flow alignment. As part of the Vertical axis tidal turbines in Strangford lough project (VATTS), the upstream flow has been measured using acoustic doppler profilers (ADP) mounted on the TEC during its operation in Strangford lough. Recommendations of IEC-200 were followed when mounting the ADPs relative to Gkinetic. However, the continuous repositioning of the TEC according to the prevailing tidal regime affects the ADPs heading. The implications of the spatial variation of the rotor’s upstream velocity on the resource assessment and device performance are not clear since this situation is not typical.To investigate the spatial variation of the upstream velocity two ADCP deployment locations were made. A seabed (upward facing) ADCP as per the current standards and a device mounted (downward facing) ADCP upstream of the rotor plane. Evaluation of the influence of the following three factors were made: i) the ADPs direction repositioning according to prevailing tidal regime, ii) the proximity of the sensors to the sea-surface, and iii) the proximity of the sensors to the TEC.These three factors will be evaluated using ADP datasets collected at Strangford narrows during the VATTS project. The datasets were obtained at approximately the same location of the TEC operation. They enable the study of the following scenarios 1) incoming flow to the rotors during operation, 2) incoming flow on undisturbed conditions (no turbine operation), and 3) a harmonic analysis prediction of the undisturbed incoming flow, which solely captures the tidal-driven flow.The investigation of these three scenarios will provide a better understanding on the rotor’s upstream flow spatial variation, and the influence of the device’s proximity and near sea surface conditions on the mean flow. These findings would benefit developers of alternative TEC designs that operate near the sea-surface.

Convolutional neural network-based seismic fragility analysis of subway station structure considering spatial variation of site shear-wave velocity

Prior research demonstrated that the uncertainty of soil parameter can significantly impact the seismic response analysis and seismic performance evaluation of underground structures. To this end, the seismic response of a three-story, three-span subway station embedded in a typical layered engineering site was investigated in this study and the uncertainty of soil parameters was explicitly considered using the shear-wave velocity interlayer correlation model. In addition, an incremental dynamic analysis considering the uncertainty of the shear-wave velocity was performed using the one-dimensional convolutional neural network (1D-CNN) model as a surrogate model for the traditional finite element method. The results indicate that the uncertainty of soil shear-wave velocity increases the average PGA values for minor, moderate, and severe failures with a probability of exceeding 50% by about 10%, and increases the logarithmic standard deviation by about 40%. When considering the uncertainty of shear-wave velocity, the discreteness of the fragility curve will increase. Moreover, the rightward shift of the fragility curve midpoint leads to a comparatively more safety seismic performance evaluation of the structure under significant seismic input.

Thermo-fluid performance enhancement in a long double-tube latent heat thermal energy storage system

Thermodynamic analysis and flow rate optimization for the long double-tube latent heat thermal energy storage systems (LHTESS) are performed. Computer modeling is carried out using created software and is based on a developed 3D non-steady non-linear coupled thermo-fluid mathematical model that combines the apparent heat capacity method and finite volume method for the sodium nitrate (NaNO3) phase change materials (PCM) and for the Syltherm800 heat transfer fluid (HTF). The mathematical model and numerical algorithm are verified through comparison with experimental data. It is found that the laminar flow of HTF ensures the uniform temperature in PCM and in HTF and this temperature is equal to the PCM melting temperature. It is proved that the PCM and HTF average temperatures along the LHTESS can be equalized using spatial and temporal velocity variations of the HTF. Mutual impact of the heat transfer and fluid mechanics parameters in the long double-tube LHTESS was studied by correlation between Nusselt numbers and Reynolds numbers. The optimal HTF flow rate parameters were analyzed based on the non-equilibrium thermodynamics method. It is discovered that the laminar regime 0 < Re < 2000 and the turbulent regime 12000<Re<15000 are the most optimal for long double-tube LHTESS of the described geometry.

Flow kinematics of granular materials considering realistic morphology

The study focuses on understanding the influence of particle morphology, interparticle friction and hopper exit width on spatial and temporal variations in velocity during dry granular flow. Using non-convex morphologies (sand, chickpea and rice), the flow characteristics and velocity fluctuations are explored. Funnel flow pattern was evident in angular shapes even in hoppers designed for mass flow discharge. K-means clustering, an unsupervised algorithm, is used to group the spatial variation of velocity inside the hopper. Three flow clusters were identified which indicate the flow transition from funnel to mass flow. The Free Flow Cluster (FFC) height was observed to be least for bulky-shaped particles because of their high sphericity and roundness values. Angular particles were observed to exhibit rapid temporal velocity fluctuations when compared to elongated and bulky shapes. Finally, the pseudo-shape approximations typically used in DEM fail to capture the true interlocking nature in the flow behaviour observed within realistic particle morphologies.

Detection of defects in highly attenuating materials using ultrasonic least-squares reverse time migration with preconditioned stochastic gradient descent

Accurate detection and characterization of defects in high-density polyethylene (HDPE) pipe materials are very important in assessing the structural integrity of critical structures in the nuclear industry. One specific challenge here is the presence of the viscoelastic attenuation of this material, which can lead to resolution degradation and loss of detail in ultrasound imaging. In this work, an effective ultrasonic imaging technique using the least-squares reverse time migration with preconditioned stochastic gradient descent (LSRTM-PSGD) is developed to improve image quality. Compared with standard ultrasonic imaging methods which only consider the direct ray path of ultrasound, least-squares reverse time migration (LSRTM) is a powerful wave-equation-based approach and it has the ability to account for rapid spatial velocity variations and to utilize all wavefield information. The LSRTM is an inversion method, which iteratively updates the reflectivity model by minimizing the modeled data and measured data. The proposed LSRTM-PSGD combines the advantages of stochastic gradient descent (SGD) and adaptive learning rate. The SGD updates the parameter on each transmitter and the fluctuation of SGD can enable it to reach a better minimum, thus improving the imaging quality. Compared with the conventional LSRTM algorithm using a fixed step size, the proposed LSRTM-PSGD algorithm can use the adaptive moment estimation to calculate the adaptive learning rate for the parameter, thereby updating the parameter appropriately. The performance of the LSRTM-PSGD algorithm is tested with experimental data. The results show high-quality reconstructed images with good resolution for defect identification in HDPE pipe materials, especially for deep defects.

On the Three-dimensionality of Flow in the Neo-sinus and its Implications for Subclinical Leaflet Thrombosis.

Subclinical leaflet thrombosis is a silent phenomenon commonly observed following transcatheter aortic valve implantation (TAVI). Leaflet thrombosis is associated with ischaemic complications and structural valve deterioration. Prior studies have shown that blood stasis in neo-sinus contributes to the initiation and growth of subclinical leaflet thrombosis. This study aimed to quantify temporal and spatial characteristics of the flow field from a fundamental perspective. in vitro experimental analysis and fluid-solid interaction simulations were employed to characterize the flow field of a transcatheter aortic valve (TAV) with an intra-annular design in a pulse duplicator. Blood residence time (BRT) and flow-induced viscous shear stress were measured in the neo-sinus and on the surface of TAV leaflets. Temporal and spatial velocity variations were observed in neo-sinus, indicating that the flow is time-dependent and fully three-dimensional. The degree of blood stasis in the neo-sinus (bulk fluid) and on the surface of the TAV leaflets highly depends on the local flow characteristics. Regional flow variation in the neo-sinus resulted in substantial variations in BRT magnitude in the neo-sinus and on the surface of the TAV leaflet. Areas with a high degree of blood stasis were observed near the fixed boundary edge of the leaflets. The study indicated that leaflet motion is a primary driver of flow in neo-sinus. Considering the substantial variations in BRT magnitude in the neo-sinus (bulk fluid), blood stasis should be quantified locally on the surface of foreign (valve) materials to avoid errors in forecasting the risk of subclinical leaflet thrombosis in patients undergoing TAVI.

Unraveling an enigmatic boundary along the Sunda-Banda volcanic arc

This study utilizes a range of complementary geological, geophysical, and geochemical data to analyze the structural, deformational, and compositional variations along the Sunda-Banda volcanic arc transitional zone from oceanic to continental subduction. The core component is a synthesis of three station-based anisotropy inferences and two 3-D shear wave velocity models in the crust and upper mantle, all of which are derived based on ∼5 years of broadband seismic data collected across eastern Indonesia. These seismic results are based on receiver functions, shear wave splitting, ambient noise tomography, and a new teleseismic surface wave tomography model. We observe distinct along-arc spatial variations in the shear wave velocity and anisotropic structure within the crust and mantle wedge above the subducting slab. An intriguing arc-perpendicular orientation is observed in crustal fabrics and mantle anisotropy consistently in central Flores, contrasting with the arc-parallel orientations on the western and eastern sides. The orientations correlate with the change in strike of the highest topography as well as the presence of ∼N-S aligned cinder cones in central Flores. The 3-D shear wave velocity model in the crust and uppermost mantle also presents a sharp structural change in central Flores that indicates a relatively thinner crust. At deeper depths, the newly imaged upper mantle structure exhibits along-arc variations, but the change across central Flores appears to be distributed more broadly and outlines a relatively slow mantle wedge beneath eastern Flores. These new observations roughly correlate with previously identified changes in volcanic geochemistry characteristics across central Flores. Our study links the surface topography, geology, and volcanism with subsurface crust and mantle structures, unraveling an enigmatic structural and/or compositional boundary along the Banda volcanic arc.

Seismic wave propagation simulations in Indo-Gangetic basin using spectral element method

SUMMARY This study focuses on developing a 3-D computational model of the Indo-Gangetic basin (IG basin) using the spectral element method. The region includes the subcontinent's most densely populated areas. The basin is unique as it consists of geologically younger sedimentary layers along with several ridges and depressions in its domain. However, the proximity of great Himalayan earthquakes and the presence of thick sedimentary layers of the basin results in higher seismic hazards. The limited instrumentation of the domain poses challenges in understanding the response of the basin due to a seismic event. This motivated us to develop a computational model of the IG basin by incorporating the best-known geometry, material properties and fine resolution topography. In the lateral direction, the modelled part of IG basin spans over ∼6° × 4° (between longitude 80.5°–86.5°E and latitude 25°–29°N). The validation of the developed basin model is performed by simulating the ground motions for the 2015 Mw 7.9 Nepal main shock and five of its aftershocks. Both qualitative and quantitative comparison of the simulated time histories suggests that the developed model could accurately simulate ground motions over a frequency range of 0.02–0.5 Hz. The developed basin model is then used to understand the seismic wavefield characteristics during the 2015 Mw 7.9 Nepal main shock. The spatial variation of peak ground velocity (PGV), as well as amplification, are investigated at a 0.2° × 0.2° grid and selected cities in the basin. The contours of PGV amplification indicate a higher value of ∼8–10 in the horizontal direction and ∼2.5–3.5 in the vertical direction for sediment depth &amp;gt;4 km. A comprehensive comparison of the simulated PGVs and the ground motion prediction equations shows that, while the simulations agree with the prediction, they also show heterogeneity of ground-motion distribution that cannot be fully described by empirical prediction relations. Hence the results from this study are more reliable and find applications in seismic hazard assessment of the cities in the basin. Besides, the results can be used to guide the installation of future seismic stations in the region.

Characterizing the spatial variations of wind velocity and turbulence intensity around a single Tamarix tree

Characterizing airflow and turbulence patterns around real vegetation is essential for predicting aeolian erosion. However, few studies have explored the airflow field around live plants. In this field study, airflow field and turbulence patterns were investigated around a single Tamarix tree. Wind speeds were monitored at 34 locations around the tree at the heights of z/h = 0.13 h, 0.5 h, 1.1 h, and 1.8 h (where h is the height of the tree) in a wind speed of 12.5 m s−1. The results showed that a half-ellipse deceleration zone formed downwind and full-ellipse acceleration zones on the sides of the tree. The largest turbulence intensity was observed at lower heights and in the leeside of the tree where wind speed was highest, and the smallest was found on the sides where wind speed accelerated. On the sides of the tree the structure of wind speed and turbulence profiles was similar and no significant differences (P < 0.001) in wind speeds were found between identical locations. The mean wind velocities downwind of the tree at 0.5 h–7 h and DR1-DR4 (at the right side of the tree edge) were significantly different to the approach flow (wind speeds at −7 h) but no statistical differences were observed between wind speeds in other locations and the approach flow. The values of Rc∆x, z (wind velocity reduction coefficient) were higher in the wake of the tree than upwind and on the sides of the tree indicating that the sheltering effect of the tree extended to the distance of seven times the height tree. This study represents an important investigation of the plant effect on airflow and the results can be used to inform Tamarix management and support parameterization of drag partition schemes to improve the accuracy of aeolian transport models in landscapes with Tamarix.

Spatiotemporal Variability of Earthquake Source Parameters at Parkfield, California, and Their Relationship With the 2004 M6 Earthquake

AbstractEarthquake stress drop is an important source parameter that directly links to strong ground motion and fundamental questions in earthquake physics. Stress drop estimations may contain significant uncertainties due to such factors as variations in material properties and data limitations, which limit the applications of stress drop interpretations. Using a high‐resolution borehole network, we estimate stress drop for 4551 (M0‐4) earthquakes on the San Andreas Fault at Parkfield, California, between 2001 and 2016 using spectral decomposition and an improved stacking method. To evaluate the influence of spatiotemporal variations of material properties on stress drop estimations, we apply different strategies to account for spatial variations of velocity and attenuation changes, and divide earthquakes into three separate time periods to correct temporal variations of attenuation. These results show that appropriate corrections can significantly reduce the scatter in stress drop estimates, and decrease apparent depth and magnitude dependence. We find that insufficient bandwidth can cause systematic underestimation of stress drop estimates and increased scatter. The stress drop measurements from the high‐frequency borehole recordings exhibit complex stable spatial patterns with no clear correlation with the nature of fault slip, or the slip distribution of the 2004 M6 earthquake. Temporal variations are significantly smaller, less well resolved and varying spatially. They do not affect the long‐term stress drop spatial variations, suggesting local material properties may control the spatial heterogeneity of stress drop.

Failure and fragmentation of ceramic target with varying geometric configuration under ballistic impact

The failure and fragmentation of monolithic bare alumina 99.5% ceramic target and energy dissipation of steel 4340 projectile have been studied in a series of ballistic experiments carried out, with the incidence velocities in a range, 122–290 m/s. The velocity drop and energy dissipation increased with incidence velocity for 10 mm thick target with damage zone extended upon the whole area of rear face at higher velocities. The ballistic results obtained with the 10 mm thick target have been compared with the ballistic performance of the 5 mm thick target used in a previous study to explore the effects of target thickness on the failure mechanism. A model for the residual velocity of projectile after perforation of the single layered ceramic target has been developed based on the Lambert Jonas model by using the experimental data available for 5 mm and 10 mm thick alumina 99.5% target against 10.9 mm projectile. The residual velocities and damage patterns were reproduced with a reasonable amount of accuracy by a three-dimensional finite element model developed on commercial ABAQUS/CAE. The effect of obliquity and projectile diameter to target thickness ratio (D/T) on ballistic performance has been determined by the numerical simulation model with impact velocity in a range of 300–500 m/s. A spatial variation of ejected fragments velocity at different time steps was plotted to develop a velocity profile for the ceramic fragments coming out of the target. A semi-empirical model has been proposed for residual velocity after perforation of a monolithic ceramic target, relating to the incidence velocity and projectile diameter to target thickness ratio. The monolithic ceramic targets have been investigated for a comparative assessment of energy dissipation by the ceramic layer to eventually design an efficient front layer of a ceramic based composite armour in future studies.

Spatial variation in mechanical properties along the sciatic and tibial nerves: An ultrasound shear wave elastography study

Ultrasound shear wave elastography has become a promising method in peripheral neuropathy evaluation. Shear wave velocity, a surrogate measure of stiffness, tends to increase in peripheral neuropathies regardless of etiology. However, little is known about the spatial variation in shear wave velocity of healthy peripheral nerves and how tensile loading is distributed along their course. Sixty healthy young adults were scanned using ultrasound shear wave elastography. Five regions of the sciatic (SciaticPROXIMAL, SciaticDISTAL) and tibial nerve (TibialPROXIMAL, TibialINTERMEDIATE, and TibialDISTAL) were assessed in two hip positions that alter nerve tension: 1) neutral in supine position; and 2) flexed at 90°. Knee and ankle remained in full-extension and neutral position. We observed spatial variations in shear wave velocity along the sciatic and tibial nerve (P < 0.0001). Shear wave velocities were significantly different between all nerve locations with the exception of SciaticDISTAL vs. TibialINTERMEDIATE (P = 0.999) and TibialPROXIMAL vs. TibialINTERMEDIATE (P = 0.708), and tended to increase in the proximal-distal direction at both upper and lower leg segments. Shear wave velocity increased with hip flexion (+54.3%; P < 0.0001), but the increase was not different among nerve locations (P = 0.233). This suggests that the increase in tensile loading with hip flexion is uniformally distributed along the nerve tract. These results highlight the importance of considering both limb position and transducer location for biomechanical and clinical assessments of peripheral nerve stiffness. These findings provide evidence about how tension is distributed along the course of sciatic and tibial nerves.