Direct noise simulation of an installed Controlled Diffusion airfoil at high angle-of-attack

Electrophysiological features of glioblastoma cells (GBCs) remain largely elusive, challenging our comprehension of glioblastoma pathophysiology. Spiking GABAergic-OPC tumor cells were recently described in IDH-mutant glioma, correlating with prolonged patient survival. Here, we characterize single-cell features at the neocortical leading edge (LE) of glioblastoma patients using combined electrophysiological, morphological, and transcriptomic profiling. We examined GBCs and non-tumor cells using acute and cultured organotypic slices of cancer-infiltrated neocortical tissues from glioblastoma patients. Electrophysiological properties of LE cells were investigated using whole-cell patch-clamp recording, with dye loading to characterize single-cell morphology. We used Patch-seq to determine the transcriptomic features of recorded LE cells and discriminate tumor and non-tumor cells, followed by gene set enrichment analysis (GSEA) and CellChat to identify differential gene expression and signaling. Upon depolarization, more than half of LE cells show aberrant action potentials (aAPs), akin to neurodevelopmental cells. Reconstructed LE cells have abnormal somatodendritic morphology. Patch-seq revealed that GBCs and non-tumor cells share a similar electrophysiological phenotype, including aAP generation, depolarized membrane potential, and elevated input resistance. Transcriptomic analysis shows that the aAP phenotype occurs across diverse GBC states and correlates with lower enrichment of proliferation-related pathways at the single-cell level, but higher enrichment of inflammatory/immune, angiogenic, and mesenchymal transition pathways. Non-tumor cells exhibit hybrid transcriptomic signatures, with predominantly neuronal but minor enrichment of astrocytic features. We find electrophysiological aAP behavior of GBCs in human glioblastoma, closely resembling that of hybrid cells in IDH-mutant glioma, supporting the hypothesis of neuronal mimicry across different glioma types.

To address the strongly coupled and highly nonlinear optimization problems arising from the increasing system complexity, optimization objectives, and variable dimensions in practical engineering applications, this paper proposes a multi-strategy enhanced NSGA-III algorithm (MSNSGA-III) by introducing K-means clustering, an adaptive hybrid operator, and an assistant evolutionary population strategy on the basis of the NSGA-III algorithm. This algorithm overcomes the performance limitations of the original algorithm in large-scale search with multiple variables. By employing the DTLZ test functions with different variable dimensions and conducting comparisons with six other representative algorithms, the proposed algorithm is proven to have strong competitiveness in terms of diversity and convergence speed. To reflect the superiority of the algorithm in practical applications, this paper establishes a variable-thickness optimization model for the morphing leading edge. By adopting the spline curve-based optimization variable control strategy and the MSNSGA-III algorithm, the optimal thickness distribution of the leading edge skin is obtained. The results show that, compared with the leading edge with a fixed skin thickness of 1.5 mm, the optimized variable thickness skin leading edge achieves 43.6% improvement in shape maintaining accuracy, 40.9% improvement in deformation accuracy, and 17.5% reduction in driving force.

Empirical evidence shows that evolution may take place during species' range expansion. Indeed, dispersal ability tends to be selected for at the leading edge of invasions, ultimately increasing a species' spreading speed. However, for organisms across many different taxa, higher dispersal comes at the cost of fitness, producing evolutionary trade-offs at the leading edge. Using reaction-diffusion equations and adaptive dynamics, we provide new insights on how such evolutionary processes take place. We show how evolution may drive phenotypes at the leading edge to maximize the asymptotic spreading speed, and we give conditions under which phenotypic plasticity in dispersal is selected for under different dispersal-reproduction trade-off scenarios. We provide some possible future research directions and other systems where the framework can be applied.

This paper presents a multiple water droplet impact finite element model that can be used to simulate high strain rate water droplet erosion processes for various target materials. The model is able to provide predictions for mass loss and the evolution of erosion depth as a function of the number of impacts. This is achieved through a continuum damage mechanics approach coupled with element deletion for the target material. Validation of the model is performed by comparison with water droplet erosion data for PMMA. We apply the model to estimate the emissions of microplastics from wind turbines due to blade erosion. For adverse weather and operational conditions, our worst-case estimate was to the order of 340 g per blade per year. The developed framework is also used to model the effect of flaws in the blade coating on erosion progression. The effect of internal defects (voids) in the coatings on the erosion depth evolution was studied numerically. The presence of internal voids led to earlier coating breakthrough and exposure of the substrate material. The model can be used to study the effects of various types of flaws during both the incubation and mass loss stages of erosion.

Understanding adaptation at species' climate limits is key for predicting evolutionary and ecological responses to climate change. In montane environments, warming may drive species distribution shifts, yet the adaptive potential of populations at leading and rear edges remains unclear. Few studies have simultaneously tested both fitness and local adaptation across elevational range limits. We conducted common garden experiments across the range of Erythranthe laciniata, an annual plant endemic to the Sierra Nevada, to test the disequilibrium hypothesis (higher fitness at leading edges, signalling range shifts) and the rear-leading edge hypothesis (lower adaptive differentiation at the leading edges due to founder effects and limited genetic variation). Fitness was highest at the high-elevation garden, supporting potential range expansion and revealing strong high-elevation climate adaptation, challenging assumptions of low adaptive potential at leading edges. This study provides a rare empirical test of both hypotheses and highlights the conservation importance of high-elevation edge populations.

Investigation of cavitation flow characteristics and vortex structures on a new lifting-body model

The control of a ship’s airflow is especially tricky under yaw effects. This paper numerically studies the streamwise suction (SS) active flow control (AFC) on the Chalmers ship model (CSM) for suppressing force fluctuations on the ship body and turbulent fluctuations in the wake region. There are two yaw angles of interest, which are 15 and 45 deg, typically representing mild and severe yaw effects. The SS AFC is implemented immediately downstream of the sharp-edged front surface as inspired by prior studies in suction control. Beyond achieving effective mitigation of fluctuations, the goal here is to understand the flow control mechanism by analyzing flow characteristics and vortical activities. A large-eddy simulation with a wall-adapting local-eddy viscosity model is conducted and is complemented by experimental tests for validation. Two cases are studied at each yaw condition: the baseline CSM without control and the AFC case with SS activated along the leading edges (LEs) of the roof and of the leeward superstructure surfaces. Results show that full-flow attachments are achieved downstream of the suction slots, regardless of the sharp superstructure LEs. The airwake vortex structure and vortex dynamics are altered substantially, leading to the reduction of drag and side-force fluctuations. Turbulent fluctuation is also effectively suppressed at both yaw conditions, which can benefit maritime helicopter operations. As indicated by the proper orthogonal decomposition analysis, the suppression mechanism differs between the two cases, where the 15 deg case links to the weakening of shedding activities and the 45 deg case results from limiting vortex–vortex interactions.

The aeroelastic behavior of insect-inspired flexible flapping wings (FFWs) directly dictates flight performance and is critical for the efficient operation of FFW-based aerial vehicles. However, most existing FFW models fail to simultaneously account for coupled twisting and bending, limiting their ability to accurately capture how leading-edge (LE) local flexibility affects aerodynamics. To address this, an FFW aeroelastic modeling method is proposed. Structurally, an analytical model coupling LE bar bending with wing membrane twisting is introduced, using nonlinear displacement–strain relations for geometric equations. Aerodynamically, the total aerodynamic load is decomposed into four components, and the dynamic equations are derived using Lagrange’s principle. Comprehensive validation shows that the Rayleigh dissipation-integrated model agrees well with high-fidelity computational fluid dynamics (CFD)/computational structural dynamics (CSD) simulations, with its computing time reduced to less than one-thousandth of CFD/CSD, realizing a remarkable improvement in computational efficiency. Parametric studies under the adopted kinematic conditions (sweeping amplitude 60 deg, frequency 25 Hz, passive pitching motion) reveal that 1) maximum vertical force and efficiency are achieved at an aspect ratio (AR) of 3; 2) reducing LE bar stiffness increases peak vertical force by 31% and results in a more pronounced “8”-shaped wingtip trajectory; and 3) increasing membrane stiffness from 105 to 107 Pa boosts peak vertical force by 12%. In conclusion, this low-cost method accurately captures FFW deformation and aerodynamics under aerodynamic-inertial coupling, supporting high-efficiency FFW vehicle design.

This study presents a comprehensive experimental investigation of flutter, post-flutter, and limit-cycle oscillations (LCOs) in very flexible swept-back wings, extending the Pazy wing benchmark to 10 and 20° sweep. Wind-tunnel tests on two models, each with leading-edge (LE) or trailing-edge (TE) tip weights, revealed two distinct flutter mechanisms: a low-speed, high-frequency hump flutter (LE) and a high-speed, low-frequency hard flutter (TE). Flutter onset sensitivity to deformation varied significantly: the hump flutter of the LE configuration was extremely sensitive to wing deformation, while the hard flutter in the TE configuration showed minimal sensitivity. Post-flutter responses exhibited superharmonic vibrations scaling with amplitude, while LCO tests identified small-amplitude, non-stall-driven oscillations and large-amplitude, stall-driven cases with subharmonics. The results demonstrate that mode coupling, rather than sweep-induced aerodynamics, governs flutter and nonlinear responses in these wings and provide a high-fidelity data set for validating nonlinear aeroelastic models.

Low-noise design is a crucial technology in the design of civil aircraft. Lift devices are among the primary noise sources during commercial aircraft takeoff and approach, with slat noise often dominating. Due to spatial constraints, traditional porous and honeycomb materials are unable to reduce low-frequency noise effectively. Therefore, based on the subwavelength-scale characteristics of acoustic metamaterials, we have designed compact metaliners for low- to midfrequency noise suppression. The metaliners are placed at the leading edge (LE) of the main wing (meta-LE) and on the inner side of the slat (metaslat). The meta-LE and metaslat exhibit wideband sound absorption capacity in the frequency ranges of 600–1600 Hz and 1500–4000 Hz. Experiments are conducted in the FL52 low-speed wind tunnel. The results indicate that at a freestream velocity of 68 m/s and an angle of attack (AOA) of 12 deg, the meta-LE achieves an average noise reduction of 3.1 dB in the designed frequency across 17 far-field microphones. The metaslat demonstrates an average noise reduction of 1.1 dB in the designed frequency range. Additionally, at an AOA of 16 deg, two tones emerge for the baseline, and the noise from installing the meta-LE and metaslat is reduced by 5.6 and 3.1 dB, respectively, at far-field microphones.

Abstract To reveal the influence laws of casing abradable coating wear on compressor aerodynamic performance, a numerical simulation study was conducted on the performance of Rotor 37 under high-speed scraping conditions with different hardness coating wear morphologies. The results show that compressor isentropic efficiency and outlet mass flow are sensitive to scraping-induced morphology changes. The medium-hardness coating causes the most significant performance degradation, with maximum reductions reaching 1.96% and 1.39%, respectively, while the pressure ratio shows little variation. Scraping grooves aggravate mixing losses between leading-edge (LE) leakage flow and mid-chord (MID) leakage flow. The tip leakage flow pushes suction-side separation vortices toward the main flow path. Under medium-hardness coating scraping conditions, the maximum entropy generation region affects up to 9.1% blade height and induces tip leakage vortex-shockwave interactions, resulting in substantial tip losses. The compressor aerodynamic performance is less affected by wear zone roughness, with the maximum isentropic efficiency reduction being only 0.31%. When wear zone roughness increases, near-wall turbulence fluctuations intensify and separation zones expand, causing flow structure changes in tip leakage paths and blade wake regions, which shifts the compressor aerodynamic characteristics toward lower flow rates. The study demonstrates that coating hardness alters leakage flow structures through wear morphology depth: medium-hardness coatings with the deepest wear grooves exhibit maximum performance deterioration, while high-hardness coatings show better wear resistance and performance maintenance.

Distributed propulsion is a promising concept for future urban air mobility aircraft, enabling lower emissions, higher efficiency, and improved maneuverability. However, aerodynamic interactions between propellers and wings may induce additional noise. Large-eddy simulations for a tractor-configured distributed propulsion system are conducted to gain further insights into the tip-vortex-impingement noise on the wing leading edge. The Ffowcs-Williams and Hawkings method is employed to determine the noise emission to the far field. Comparison of the simulation results with experimental and numerical reference data demonstrates good accuracy of the numerical methods. Results reveal that propeller tip vortices impinging on the wing leading edge generate pressure pulses at the blade-passing frequency. Acoustic footprints are extracted from the hydrodynamic pressure perturbations of the wing near field using a surface-based noise source localization method, which identifies tip-vortex-impingement noise and trailing-edge noise as dominant sources on the installed wing. Although propeller noise remains the primary contributor to overall emissions, propeller–wing interaction leads to a 1–3 dB increase in the noise levels. Both tip-vortex-impingement noise and the trailing-edge noise from the wing exhibit dipole-like directivity, radiating primarily normal to the freestream flow. This study highlights mechanisms and key areas for potential noise mitigation strategies in distributed propulsion systems.

Mesenchymal cell migration starts with the protrusion of the cell’s leading edge, enabled by the branching growth of the actin network. Two crucial molecular players in protrusion are actin filaments and the Arp2/3 protein complex, the branching agent. Traditionally, protrusion models are intuited from several perturbative experiments. Recent multiplex microscopy imaging data promise to drastically change this paradigm by providing measurements of naturally fluctuating densities of key proteins at the leading edge of unperturbed cells. We report the first attempt to reconstruct the mechanistic protrusion model from such data. We analyze fluctuations of F-actin and Arp2/3 densities and cell edge velocity using phase space and regression analysis to reconstruct linearized stochastic actin-Arp2/3-velocity coupled dynamics. We then build a nonlinear partial differential equation model of these dynamics based on previous knowledge of this system and parsimony. The resulting model recovers the rates of reactions and mechanical and transport processes in the lamellipodium from a single non-perturbative experiment. The model posits that the only essential nonlinearities in the lamellipodial dynamics stem from the retrograde flow of F-actin. The model suggests that the protrusion is dominated by a damped oscillatory cycle resulting from a combination of positive feedback from Arp2/3 to protrusion velocity and negative feedback from F-actin to the velocity.Significance statementTraditionally, models of intracellular mechanochemistry are intuited from perturbative experiments. Multiplex microscopy imaging changes this by providing measurements of naturally fluctuating densities of key proteins in unperturbed cells. We use such data to reconstruct a mechanistic model of cell leading edge. We build equations for actin system and edge velocity using data, previous knowledge and parsimony. The resulting model recovers the rates of reactions and mechanical and transport processes at the leading edge. The model suggests that the protrusion is dominated by a damped oscillatory cycle resulting from a combination of positive feedback from Arp2/3 to protrusion velocity and negative feedback from F-actin to the velocity.

Abstract The control of bluff-body wakes for reduced drag and enhanced stability has traditionally relied on the so-called direct-wake control approach. By the use of actuators or passive devices, one can manipulate the aerodynamic loads that act on the rear of the model. An alternative approach for the manipulation of the flow is to move the position of the actuator upstream, hence interacting with an easier-to-manipulate boundary layer. The present study will focus on a bluff-body flow solved via large-eddy simulations (LES) to investigate the effectiveness of an upstream plasma actuator (positioned at the leading edge) with regard to the manipulation of the wake dynamics and its aerodynamic loads. A rectangular cylinder with rounded leading edges, equipped with actuators positioned at the front curvatures is simulated at Re=40000. This geometry is representative of ground-vehicle configurations, such as truck cabs, and the present study highlights the potential of active flow control for such applications. The results show that sinusoidal actuation yields significantly greater performance than steady actuation. Both drag reduction and cross-flow load attenuation improve with increasing actuation frequency, up to a saturation point. A maximum drag reduction of approximately 40% is achieved in the optimal case.

Legacy modernization constitutes a formidable technical and strategic challenge for enterprises maintaining large-scale software infrastructures. Systems accumulate complexity through decades of incremental development, resulting in tangled dependencies, obsolete frameworks, and inconsistent application programming interfaces. Manual migration approaches prove costly and hazardous due to dependence on institutional knowledge that frequently disappears over time. Conventional methods involving manual code rewriting introduce defects, prolong system unavailability, and impede innovation cycles. Recent advances in artificial intelligence have fundamentally altered modernization methodologies. Contemporary intelligent migration frameworks synthesize code comprehension models, dependency graph analytics, and predictive validation mechanisms to automate substantial portions of migration workflows. Machine learning architectures now parse, categorize, and translate complex codebases while maintaining high degrees of semantic integrity, though challenges remain as language models occasionally fail to preserve complete semantic equivalence. These enhanced systems diminish human error during transformation operations and strengthen system dependability, facilitating modernization efforts at scales previously deemed impractical. This article explores architectural underpinnings, operational mechanisms, security protocols, and implementation challenges within these frameworks, illustrating their capacity to convert legacy modernization from episodic reconstruction initiatives into perpetual evolutionary maintenance processes.

This paper experimentally investigates grid-generated turbulence and its interference on a downstream airfoil. The grid is positioned at the nozzle exit of an acoustic wind tunnel and is defined by bar windward side width d and grid size M. The Reynolds number based on the airfoil chord length C is 2×105. The airfoil varies by replacing the solid leading edge (LE) with a wavy LE of different amplitudes A/C (0.1∼0.3) and combined LE porosity σ (6∼13%) at an angle of attack of σ (0∼20 deg). Noise measurements indicate that this grid-generated turbulence is primarily suitable for studying turbulence–airfoil interaction noise at low frequencies, specifically below the grid-bar vortex shedding frequency. To enhance noise measurement resolution, the airfoil is better placed downstream between L/M=5 and 10 (where L is the streamwise distance). In low frequencies, noise reduction efficiency improves with increasing wavy LE amplitude A and the combined normal-direction porosity σ under specific angle α. Flow visualization reveals that the inhomogeneous vortices shed from the grid transition into homogeneous and isotropic turbulence after L/M=5, impinging upon the airfoil LE and generating interaction broadband noise. Force measurement results show that although the maximum lift coefficient of the airfoil with a wavy LE may decrease, the wavy LE exhibits the characteristic of delaying stall.

Unmanned aerial vehicles (UAVs) with flying wing designs offer unique advantages in terms of maneuverability and fuel efficiency, but achieving precise control over these tailless aircraft can be challenging. This study investigates the potential of notch leading edge (NLG) technology to improve the effectiveness of control surfaces in flying wing UAVs. NLG refers to a design feature where notches or depressions are strategically incorporated along the leading edge of the wings. This seemingly minor modification can significantly impact the aircraft′s aerodynamic performance and controllability. The present research leverages numerical methods to meticulously examine the influence of NLG placement on a crucial parameter: the roll torque coefficient. This coefficient quantifies the effectiveness of control surfaces, such as split drag rudder, in yawing moments, essential for maneuvering the aircraft. The investigation adopts a parametric approach, meticulously varying the dimensions and positions of the NLG along the wing span. This comprehensive analysis reveals a fascinating relationship between NLG placement and control surface efficacy. The study convincingly demonstrates that positioning the NLG closer to the wing root, where the wing meets the fuselage, yields superior results compared to placements near the wingtip.

The Editorial Calendar details upcoming publication plans for The Leading Edge.

For hypersonic air-breathing vehicles, the V-shaped leading edges (VSLEs) of supersonic combustion ramjet (scramjet) inlets experience complex shock interactions and intense aerodynamic loads. This paper provides a comprehensive review of flow characteristics at the crotch of VSLEs, with particular focus on the transition of shock interaction types and the variation of wall heat flux under different freestream Mach numbers and geometric configurations. The mechanisms governing shock transition, unsteady oscillations, hysteresis, and three-dimensional effects in VSLE flows are first examined. Subsequently, thermal protection strategies aimed at mitigating extreme heating loads are reviewed, emphasizing their relevance to practical engineering applications. Special attention is given to recent studies addressing thermochemical nonequilibrium effects on VSLE shock interactions, and the limitations of current research are critically assessed. Finally, perspectives for future investigations into hypersonic VSLE shock interactions are outlined, highlighting opportunities for advancing design and thermal management strategies.