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We present comprehensive numerical results from a study of model H, which describes phase separation kinetics in binary fluid mixtures. We study the pattern dynamics of both density and velocity fields in d = 2, 3. The density length scales show three distinct regimes, in accordance with analytical arguments. The velocity length scale shows a diffusive behavior. We also study the scaling behavior of the morphologies for density and velocity fields and observe dynamical scaling in the relevant correlation functions and structure factors. Finally, we study the effect of quenched random field disorder on spinodal decomposition in model H. [ABSTRACT FROM AUTHOR]

Local phonon motion underneath a surface interacting with a flow may cause the flow to passively stabilize, or destabilize, as desired within the region adjacent to the subsurface motion. This mechanism has been extensively analyzed over only a spatial region on the order of the instability wavelength along the fluid–structure interface. Here, we uncover fundamental relations between the behavior of flow instabilities and the frequency response characteristics of the phononic subsurface structure admitting the elastic motion. These relations are then utilized to demonstrate the possibility of extensive spatial expansion of the control regime along the downstream direction with minimal loss of performance—potentially covering the entire surface exposed to the flow. [ABSTRACT FROM AUTHOR]

The present study investigates the vibration analysis of cylindrical shells composed of fiber metal laminate (FML) with embedded piezoelectric layers, undergoing fluid-structure interaction (FSI) and resting on a Pasternak elastic foundation based on the principles of three-dimensional elasticity theory. Using the state space approach, the equations of motion were derived under simply supported boundary conditions. The natural frequencies of the FML cylindrical shell, accounting for the presence of a moving fluid, were computed by solving the eigenfrequency equations. The study examined the influence of various parameters, including boundary conditions, length-to-radius ratio, fluid type, fluid velocity, circumferential wave number, and radius-to-thickness ratio, on glass-reinforced aluminum laminate (GLARE), aramid-reinforced aluminum laminate (ARALL), and carbon-reinforced aluminum laminate (CARALL). A constant composite/metal volume ratio was assumed. The results obtained were validated by comparing with natural frequency values from the existing literature, confirming the agreement and convergence with previous studies. The results confirm that the highest natural frequency values are assigned to the CARALL, ARALL and GRALE structures in descending order. Furthermore, an increase in fluid flow velocity through the cylindrical shell correlates with a reduction in natural frequency. [ABSTRACT FROM AUTHOR]

In this study, we investigated the integration of an NdFeB N35 permanent magnet into an electromagnetic chuck to maintain its magnetic force continuously. By energizing or deenergizing the coil wrapped around the chuck, the surface magnetic force was increased or decreased, achieving either stronger adhesion or easy detachment of the attached object, respectively. ANSYS Maxwell software was utilized to simulate the initial model, the results of which were then compared with physical measurements. Keeping the external dimensions unchanged, the yoke's dimensions were used as the parameters to analyze the effect of changes in dimensions at different positions on the electromagnetic chuck's surface adhesion force. Differences between simulated and measured results for the initial model after energizing the electromagnetic chuck were within 6%. Among the simulations with different parameters, changes in the thickness of the outer frame base and inner diameter did not significantly affect the magnetic flux on the surface of the electromagnetic chuck. Therefore, these results were not shown in this study. Alterations in the yoke's dimensions affected the relative position and size of the coil or created new magnetic flux paths. A distance of less than 1 mm between the coil and the chuck surface significantly affected the surface magnetic flux density. [ABSTRACT FROM AUTHOR]

In this study, we conducted stress and strain analyses on the eyeball under pressure using the finite element simulation software Ansys. The eyeball model was constructed using SolidWorks, and additionally, it simulates a contact-type tonometer, applying pressure to the eyeball through probe force variations and calculating the pressure changes inside the eyeball. Initially, the cornea, sclera, ciliary body, suspensory ligaments, aqueous humor, and vitreous humor were combined using SolidWorks. Subsequently, the model was imported into Ansys for meshing, boundary setting, and simulation calculation. Finally, the analysis results were extracted using the Ansys postprocessor and the simulated data were validated against actual measurement data to ensure accuracy. Material properties necessary for the eyeball under pressure analyses were configured, with the Mooney-Rivlin hyperelastic material being selected. During compression, the cornea and sclera primarily absorbed the concentrated load after compression. Pressure was applied using a probe to observe variations in stress and strain concerning the applied force and intraocular pressure. Three probe materials (rubber, titanium alloy, and glass) were chosen for comparative simulation analyses. [ABSTRACT FROM AUTHOR]

Background: Arterial dissection, a condition marked by the tearing of the carotid artery's inner layers, can result in varied clinical outcomes, including progression, stability, or spontaneous regression. Understanding these outcomes' underlying mechanisms is crucial for enhancing patient care, particularly with the increasing use of computer simulations in medical diagnostics and treatment planning. The aim of this study is to utilize computational analysis of blood flow and vascular wall to: (1) understand the pathophysiology of stroke-like episodes in patients with carotid artery dissection; and (2) assess the effectiveness of this method in predicting the evolution of carotid dissection. Methods: Utilizing contrast-enhanced magnetic resonance angiography (MRA), we segmented images of the patient's right internal carotid artery. These images were transformed into 3D solids for simulation in Ansys multifisic software, employing a two-way fluid structure interaction (FSI) analysis. Simulations were conducted across two wall conditions (atherosclerotic and normal) and three pressure states (hypotension, normotension, hypertension). Results: The simulations indicated a significant pressure discrepancy between the true and false lumens of the artery. This suggests that flap motion and functional occlusion under hypertensive conditions could be the cause of the clinical episodes. Thrombotic risk and potential for dissection extension were not found to be critical concerns. However, a non-negligible risk of vessel dilation was assessed, aligning with the patient's clinical follow-up data. Conclusion: This study highlights specific hemodynamic parameters that could elucidate carotid artery dissection's mechanisms, offering a potential predictive tool for assessing dissection progression and informing personalized patient care strategies. [ABSTRACT FROM AUTHOR]

In response to the unanswered relevant questions surrounding atherosclerosis, it becomes imperative to investigate arterioles using sophisticated mathematical modelling techniques to shed light on critical stress and strain patterns influenced by gravity. The primary objective of this study is to scrutinize flow characteristics and probe stress and strain distributions experienced by the intima layer of arterioles, encompassing coronary, renal, cerebral, mesenteric, and pulmonary arteries, under gravitational forces. This investigation employs a fluid-structure interaction methodology utilizing arbitrary Eulerian–Lagrangian formulation. The study delves into blood flow characteristics within coronary, renal, cerebral, mesenteric, and pulmonary arterioles using the fluid-structure interaction technique, employing an arbitrary Eulerian–Lagrangian formulation. It thoroughly examines various biomechanical parameters such as the Cauchy–Green stress tensor, Principal strain, Piola–Kirchoff stress tensor, deformation tensor, and volume strain along the intima layer under the gravitational influence, elucidating vulnerable regions prone to endothelial dysfunction. Higher values of δV are found at the left shoulder and in the intima's post stenosis area due to the pressure gradient along the flow channel, whereas other intima regions show a null volume strain. A thorough understanding of stress distribution is essential to create focused therapies to lessen vascular health problems. The stress in the post-stenosis region seems to affect the endothelial layer to a significant extent. [ABSTRACT FROM AUTHOR]

The study is devoted to the hemodynamics during cerebral vascular bypass surgery for the treatment of cerebral aneurysms in two patients. The location, morphological characteristics and treatment approaches of the patients were similar, but different outcomes were observed as a result of the performed microsurgical procedures. Computational approach was used to analyze the hemodynamic differences of aneurysms, treated via extra-intra cranial (EC-IC) cerebral bypass shunt. The paper presents a new criterion based on the energy parameters of healthy compartment of cerebral circulation. The applied approach demonstrates a new effective method of preoperative risk modelling for medical decision-making. [ABSTRACT FROM AUTHOR]

The monopile-supported offshore wind turbines (OWTs) are subjected to the wave and current loadings. Affected by currents and waves, monopile-supported OWTs are also vulnerable to scour. However, the effect of scour and currents on the dynamic behavior of the monopile are not fully appreciated. This study conducted the model tests to evaluate the effect of scour depth and flow velocity on the lateral responses of support structure. Furthermore, the two-way (T-W) coupling fluid–structure interaction (FSI) method was proposed to evaluate the dynamic responses of piles in sand. The support structure is modeled using ABAQUS, a finite-element models software package, by considering the nonlinear soil–structure interaction effects, STAR-CCM + tools has been employed to model the FSI which are fed into ABAQUS to predict the structure's dynamic response. Using the proposed method, a parametric study has been conducted to evaluate the effects of scour depths, flow velocities on the dynamic responses of OWTs. The results indicate that scour altered the fundamental frequency of OWT, causing resonance. An increase in scour depth and flow velocity increased the dynamic responses of support structure, which are detrimental for the safety and stability of the OWT system. [ABSTRACT FROM AUTHOR]

This article investigates the interaction of nematic liquid crystals modeled by a simplified Ericksen-Leslie model with a rigid body. It is shown that this problem is locally strongly well-posed, and that it also admits a unique, global strong solution for initial data close to constant equilibria. The proof of the global strong solution relies on a new splitting method for the director in a mean value zero and average part. [ABSTRACT FROM AUTHOR]

In the present investigation, a detailed numerical investigation of the flow and heat transfer characteristics of a channel with an elastic fin (vortex generator) and an elastic wall has been carried out using finite element method. The Fluid- Structure Interaction (FSI) model is used to capture the interaction between the fluid and the solid structure. A sinusoidal time dependent velocity profile has been imposed at the inlet of the channel and the right half of the upper wall of the channel is heated and exposed to constant temperature boundary condition. Due to the sinusoidal velocity profile at the inlet, the elastic fin oscillates periodically and act as a vortex generator, which causes more turbulence in the flow. The obtained results showed that the Nusselt number over the heated wall is affected by the position of the flexible fin, height of flexible fin and elasticity modulus of elastic fin. Moreover, due to the elasticity of the elastic wall and sinusoidal behavior of the inlet velocity, the elastic wall oscillates periodically upward and downward. The Nusselt number values over the heated wall are increased with decrease of the elastic modulus value of the elastic wall. However, the decrease in elastic modulus value of the elastic wall contributes to an increase in the pressure drop inside the channel. It should be added that the interplay between the fluid motion and the deformable structures leads to enhanced turbulence, as the flexible fin and elastic wall introduce additional disturbances and fluctuations into the flow regime. Consequently, this heightened turbulence level has profound implications for heat transfer processes within the system. [ABSTRACT FROM AUTHOR]

This research proposes simplified methods for response spectrum and modal dynamic analyses of gravity dams using time-history and spectral seismic accelerations modified to directly account for hydrodynamic effects. The developed methods waive the need for specialized fluid-structure interaction software. They also lead to more accurate assessment of coupled structural flexibility and hydrodynamic effects due to each vibration mode than the static correction method commonly used in traditional simplified methods. The methodology utilizes analytical formulations of hydrodynamic pressure or simplified added masses to obtain the contributions of the selected vibration modes to the total seismic response. A hydrodynamic modification factor characterizing the amplification/de-amplification of acceleration seismic demands due to earthquake-induced hydrodynamic effects is also introduced. The application of the proposed methods is illustrated numerically through examples of two typical gravity dam-reservoir systems subjected to four earthquakes. The obtained results are in excellent agreement with the classical reference solutions. Time-history and spectral seismic acceleration demands modified by hydrodynamic effects as well as selected key response indicators, such as relative displacements and stresses within the studied gravity dams, are discussed. [ABSTRACT FROM AUTHOR]

The Ozaki procedure is a surgical technique which avoids to implant foreign aortic valve prostheses in human heart, using the patient's own pericardium. Although this approach has well-identified benefits, it is still a topic of debate in the cardiac surgical community, which prevents its larger use to treat valve pathologies. This is linked to the actual lack of knowledge regarding the dynamics of tissue deformations and surrounding blood flow for this autograft pericardial valve. So far, there is no numerical study examining the coupling between the blood flow characteristics and the Ozaki leaflets dynamics. To fill this gap, we propose here a comprehensive comparison of various performance criteria between a healthy native valve, its pericardium-based counterpart, and a bioprosthetic solution, this is done using a three-dimensional fluid–structure interaction solver. Our findings reveal similar physiological dynamics between the valves but with the emergence of fluttering for the Ozaki leaflets and higher velocity and wall shear stress for the bioprosthetic heart valve. [ABSTRACT FROM AUTHOR]

A numerical model is presented for solving the dam–reservoir interaction (DRI) problem in the time domain. The primary aim of this paper is to introduce a coupling method that could be simply implemented in a monolithic DRI model, yields a symmetrical system of equations, and maintains accuracy comparable to existing studies. The finite element method is employed to solve the equation of motion for the structure, and the finite volume method is for the Navier–Stokes equations in the fluid domain. These two solvers are coupled using an innovative approach to generate a pressure-based symmetric system of equations, which is resolved implicitly. Moreover, unlike most previous DRI studies, free surface waves are considered in the modeling procedure, and their effects are investigated. Comparison of the results with benchmark test cases from the literature demonstrates that the proposed numerical method is both straightforward and precise. [ABSTRACT FROM AUTHOR]

To overcome the difficulties of time-consuming and inefficient in the response calculations of the submerged cylindrical shell with internal substructures, this paper firstly presents a refined mode superposition method. In view of the necessity and difficulties of directly and quickly obtaining the frequencies and modes of structures submerged in fluid (named the wet modes), the wet modes are expanded by the modes in vacuum (dry modes) and solved by the energy method. The added kinetic energy of the fluid is calculated via boundary integration, and the Lagrange equations of the second kind is applied to the fluid-structure coupling equations. Then the wet modes are solved by eigenvalue calculation and the modal mass and stiffness of each order wet mode are obtained. Finally, they are used for establishing a mode superposition approach for response calculations. The accuracy of the present method is verified by ANSYS software. In this method, all the required data are obtained from the structural analysis and the traditional complicated fluid force modeling is no longer required. Thus it has the advantages of high computational efficiency and applicability. Compared to the traditional semi-analytic model, this modeling methodology has broad application potential for vibration problems of complex underwater structures since the structural dry modes can be solved efficiently by commercial software. It also has practical value as a theoretical reference for developing mode-superposition-based calculations for fluid-structure problems using commercial software. [ABSTRACT FROM AUTHOR]

Interactions between carbon nanotubes (CNTs) and fluid flows are central to the operation of several emerging nanotechnologies. In this paper, we explore the fluid-structure interaction of CNT micropillars in wall-bounded shear flows, relevant to recently developed microscale wall shear stress sensors. We monitor the deformation of CNT micropillars in channel flow as the flow rate and wall shear stress are gradually varied. We quantify how the micropillars bend at low wall shear stress, and then will commonly tilt abruptly from their base above a threshold wall shear stress, which is attributed to the lower density of the micropillars in this region. Some micropillars are observed to flutter rapidly between a vertical and horizontal position around this threshold wall shear stress, before settling to a tilted position as wall shear stress increases further. Tilted micropillars are found to kink sharply near their base, similar to the observed buckling near the base of CNT micropillars in compression. Upon reducing the flow rate, micropillars are found to fully recover from a near horizontal position to a near vertical position, even with repeated on–off cycling. At sufficiently high wall shear stress, the micropillars were found to detach at the catalyst particle-substrate interface. The mechanical response of CNT micropillars in airflow revealed by this study provides a basis for future development efforts and the accurate simulation of CNT micropillar wall shear stress sensors. [ABSTRACT FROM AUTHOR]

In this study, nonlinear vibrations and stability of multilayer functionally graded (FG) pipes conveying fluid laying on nonlinear elastic foundation and reinforced by graphene nanoplatelets (GPLs) are investigated with an emphasis on optimized analytical method. Various types of GPL distribution patterns are considered and to estimate the mechanical characteristics of the reinforced pipe the Halpin–Tsai micromechanics theory is applied. The nonlinear differential equation of motion is obtained by using Von–Kármán strain relations in conjunction with the Euler–Bernoulli beam theory and applying Hamilton's principle. The Galerkin technique has been used for discretizing the partial differential equation. The optimized homotopy analysis method (HAM), as a strong analytical method, is utilized to solve the nonlinear differential equation by considering different initial excitations. The convergence-control parameter is taken into account to guarantee the convergence of the analytical solution. In this study, an exact solution based on HAM for the critical flow velocity and n th nonlinear frequency is presented. Additionally, series solutions for the nonlinear time responses of the transverse and longitudinal vibrations of fluid-conveying pipe based on optimized HAM are obtained for the first time. In the numerical results, the effects of arbitrary initial conditions and different physical characteristics on the nonlinear frequencies and time responses are extensively examined. It is shown that the nonlinear frequencies and critical flow velocity of the pipe depend not only on the initial excitation amplitude, but also on the entire initial excitation function applied on the pipe. [ABSTRACT FROM AUTHOR]

To address the safety issues of bridge structures affected by local scouring from the Yellow River mudflows, this study employod bidirectional fluid-solid coupling theory and turbulence theory to establish a numerical analysis model for sand-laden mudflow impacting bridge piers, which was validated against experimental data from literature. Based on this, calculations were conducted for three different cross-sectional pillars to assess scouring effects. The results indicate that circular cross-section pillars exhibit better resistance to scouring, making them more suitable for the Yellow River bridge piers, while triangular cross-section pillars demonstrate superior diversion capabilities, rendering them more suitable for abutments. Building upon this, numerical simulations were conducted for circular cross-section bridge piers under four different sediment concentrations. Comparative analysis reveals that as sediment concentration increases, the likelihood of pier scouring by mudflows increases, corroborated by comparisons with impact forces. Moreover, within a certain range of sediment concentrations, the dynamic response of bridge piers increases with sediment concentration; however, beyond this range, the dynamic response sharply declines. [ABSTRACT FROM AUTHOR]

During the operation of a turbine, the water level drop can cause vibration and damage to the flow components, severely threatening its stability and reliability. Investigating the impact of operational parameters on the internal flow field and flow structures of tidal turbines under low flow conditions is crucial for peak shaving and deployment of tidal power stations. This paper takes a 24MW turbine as the research object, using numerical calculations to analyze the effects of tailwater height on the flow characteristics and structural properties of the unit under low flow conditions. It studies the hydraulic impact on the flow component walls under different operating parameters and verifies the reliability of numerical calculations through vibration and stress tests. The results show that the increase in tailwater level affects the turbine’s flow characteristics, forming large-scale, high-intensity vortices in the internal flow field and causing pressure pulsations near the wall surface. Modal analysis reveals that under different tailwater heights, the maximum modal effective mass exists along the axis of the impeller, with modal frequencies higher than the main frequencies of pressure pulsations. The impeller region corresponds to the turbine chamber wall bearing significant stress, which induces strain. The magnitude of stress and the degree of strain are positively correlated with the tailwater height. The research findings provide guidance for tailwater regulation and stable operation of tidal power stations. [ABSTRACT FROM AUTHOR]

Heart disease is a leading cause of mortality, with calcific aortic valve disease (CAVD) being the most prevalent subset. Being able to predict this disease in its early stages is important for monitoring patients before they need aortic valve replacement surgery. Thus, this study explored hydrodynamic, mechanical, and hemodynamic differences in healthy and very mildly calcified porcine small intestinal submucosa (PSIS) bioscaffold valves to determine any notable parameters between groups that could, possibly, be used for disease tracking purposes. Three valve groups were tested: raw PSIS as a control and two calcified groups that were seeded with human valvular interstitial and endothelial cells (VICs/VECs) and cultivated in calcifying media. These two calcified groups were cultured in either static or bioreactor-induced oscillatory flow conditions. Hydrodynamic assessments showed metrics were below thresholds associated for even mild calcification. Young's modulus, however, was significantly higher in calcified valves when compared to raw PSIS, indicating the morphological changes to the tissue structure. Fluid–structure interaction (FSI) simulations agreed well with hydrodynamic results and, most notably, showed a significant increase in time-averaged wall shear stress (TAWSS) between raw and calcified groups. We conclude that tracking hemodynamics may be a viable biomarker for early-stage CAVD tracking. [ABSTRACT FROM AUTHOR]

During the transient process of load rejection, the hydraulic pressure applied to the pump-turbine and plant concrete changes dramatically and induces high dynamic stress on the spiral case. The preloading spiral case has been widely used in large-scale pumped-storage power stations due to its excellent load-bearing capacity. However, studies on the impact of preloading pressure on the structural response during load rejection are still few in number. In this paper, 3D flow domain and structural models of a prototype pump-turbine are designed to analyze the hydraulic characteristics and flow-induced dynamic behavior of the preloading steel spiral case under different preloading pressures during load rejection. The results show that the asymmetric design of the logarithmic spiral lines ensures an axially symmetric potential flow within the spiral case domain with uniform pressure distribution. Higher preloading pressure provides larger preloading clearance, leading to greater flow-induced deformation and stress, with their maximum values located at the mandoor and the inner edge, respectively. The combined effect of the asymmetrical shape, internal hydraulic pressure and unbalanced hydraulic force leads to an asymmetrical preloading clearance distribution, resulting in an asymmetrical distribution along the axial direction but a symmetrical characteristic near the waistline of the structural response. Stress variations at sections and between sections share similar characteristics during load rejection. It follows the same trend as the hydraulic pressure under lower preloading pressures, while there is a delayed peak of stress due to the delayed contact phenomenon when the preloading pressure reaches the maximum static head. The conclusions provide scientific guidance for optimizing the preloading pressure selection and structural design for the stable operation of units. [ABSTRACT FROM AUTHOR]

We present a numerical framework bringing together a structural and a surface-energy minimization model to compute nano- and microorigami self-folding processes, that are three-dimensional in nature. A liquid drop, initially at rest on the template, triggers the spontaneous folding and deforms dynamically with the template. As application, the self-folding of thin two-dimensional templates into pyramidal microstructures is simulated. Each template is composed of a fixed regular base connected to rigid triangular side panels by two elastic hinges. We presently determine the condition, at which the transition from partial to full drop encapsulation occurs. The present model makes use of phase fields to numerically represent the drop and the template. This allows to: (i) develop an efficient computational method, which incorporates time-derivative terms and (ii) study three-dimensional complex self-folding processes. [ABSTRACT FROM AUTHOR]

The violent vibration of supersonic wings threatens aircraft safety. This paper proposes the strongly nonlinear acoustic metamaterial (NAM) method to mitigate aeroelastic vibration in supersonic wing plates. We employ the cantilever plate to simulate the practical behavior of a wing. An aeroelastic vibration model of the NAM cantilever plate is established based on the mode superposition method and a modified third-order piston theory. The aerodynamic properties are systematically studied using both the timedomain integration and frequency-domain harmonic balance methods. While presenting the flutter and post-flutter behaviors of the NAM wing, we emphasize more on the pre-flutter broadband vibration that is prevalent in aircraft. The results show that the NAM method can reduce the low-frequency and broadband pre-flutter steady vibration by 50%–90%, while the post-flutter vibration is reduced by over 95%, and the critical flutter velocity is also slightly delayed. As clarified, the significant reduction arises from the bandgap, chaotic band, and nonlinear resonances of the NAM plate. The reduction effect is robust across a broad range of parameters, with optimal performance achieved with only 10% attached mass. This work offers a novel approach for reducing aeroelastic vibration in aircraft, and it expands the study of nonlinear acoustic/elastic metamaterials. [ABSTRACT FROM AUTHOR]

To analyze the noise induced by moving rigid structures in low Mach number flows, acoustic governing equations based on the viscous/acoustic splitting method and the arbitrary Lagrangian–Eulerian method are rigorously derived. In order to resolve the numerical instability generated in a non-uniform mean flow, the modified viscous/acoustic method, based on the filtering method, is developed. The acoustic equations are transformed into the same form as the incompressible flow equations by introducing the acoustic co-velocity and solved based on a collocated grid finite volume method. An approach for solving acoustic equation based on the PIMPLE algorithm is presented and computed in open-source computational fluid dynamics software OpenFOAM, which brings down communication costs and speeds up computing efficiency. Furthermore, the source term decomposition is extended to study the noise generated by each source term in a motion grid. Several examples including stationary and moving meshes have been designed to prove the accuracy of this approach. Finally, the aerodynamic and acoustic properties for the flow past a transversely oscillating cylinder at Re = 200, Ma = 0.2 in lock-in and non-lock-in regions is present. [ABSTRACT FROM AUTHOR]

Hemodynamic analysis reveals a highly significant effect on the prevention, diagnosis, and treatment of human vascular diseases. This article goes deeply into the periodic pulsatile blood flow in the carotid artery with an elastic vessel wall. In view of blood rheological experimental data, the constitutive equation of fractional Maxwell power-law fluid with yield stress, which can describe the four characteristics of yield stress, viscoelasticity, shear thinning, and thixotropy is established. Meanwhile, drawing support from the data of pulsatile flow, the finite Fourier series of pressure gradient with a period of 1 s has been proposed. Leading into Hooke's law can build the fluid-structure coupling boundary condition of blood flow and elastic vessel wall. The numerical solutions are got hold of finite difference method integrated with the newly developed L1-algorithm, and their convergence and stability of which are verified. The axial velocities of blood under different constitutive relationships are compared. The results throw light that other constitutive relationships underestimate the velocity of blood. Furthermore, the flow rate and wall shear stress on different fluid are calculated. It can be concluded that compared with Bingham fluid, the maximum and minimum flow rate/wall shear stress of fractional Maxwell power-law fluid with yield stress increases by 19% and 32%, respectively. The flow rate lags behind the pressure gradient and has time delay effect, on the contrary, the velocity of blood vessel wall is keeping pace with the pressure gradient. The effects of relevant physical parameters on velocity are discussed. In addition, the spatiotemporal distribution of blood flow in cerebral artery and femoral artery are analyzed. HIGHLIGHTS: Fractional Maxwell power-law fluid is proposed to describe hemorheology property. Based on Hooke's law, the boundary condition of elastic wall is established. The finite Fourier series of pulsating pressure gradient has been fitted firstly. Blood flow promoted by the pressure gradient has a hysteresis effect. The velocity of blood vessel wall is keeping pace with the pressure gradient. [ABSTRACT FROM AUTHOR]

Projection-based model order reduction of dynamical systems usually introduces an error between the high-fidelity model and its counterpart of lower dimension. This unknown error can be bounded by residual-based methods, which are typically known to be highly pessimistic in the sense of largely overestimating the true error. This work applies two improved error bounding techniques, namely (a) a hierarchical error bound and (b) an error bound based on an auxiliary linear problem, to the case of port-Hamiltonian systems. The approaches rely on a secondary approximation of (a) the dynamical system and (b) the error system. In this paper, these methods are adapted to port-Hamiltonian systems. The mathematical relationship between the two methods is discussed both theoretically and numerically. The effectiveness of the described methods is demonstrated using a challenging three-dimensional port-Hamiltonian model of a classical guitar with fluid–structure interaction. [ABSTRACT FROM AUTHOR]

In recent years, there has been significant development in microfluidic devices for cell separation and sorting using acoustic methods in biomedical applications. The acoustic interparticle force (AIF) or the secondary acoustic radiation force arises from particle interactions with the scattered field of other particles, influencing particle motion at close ranges and facilitating optimal trapping and separation. This study analyzes a two-particle system consisting of a fixed particle and a white blood cell (WBC) within a standing acoustic field and creeping flow using fluid-structure interaction (FSI). To reduce computational costs by decoupling the acoustics and FSI, the acoustic pressure equation was solved on the frequency domain to calculate the total acoustic radiation force in each time step. Model accuracy was assessed by evaluating interparticle (AIF) and primary acoustic radiation force (ARF) on a polystyrene particle and comparing simulation results to analytical and experimental data. Results demonstrate the precise primary ARF computation, with discrepancies in AIF attributed to viscous losses near the particle surface. Moreover, the higher density of the fixed particle compared to WBCs induces significant acoustic interparticle attraction at close distances. Consequently, cell entrapment occurs through strong attraction and collision with fixed aluminum and silicon particles in creeping flow in all three Reynolds numbers 1.4 × 10−3, 2.1 × 10−3, and 3 × 10−3. Increasing Reynolds numbers augment the likelihood of cell separation from the fixed particle. These findings contribute to optimizing cell isolation and entrapment strategies. [ABSTRACT FROM AUTHOR]

Shock wave propagation and their damage to solid structures, which involve complex multiphase and multiphysics phenomena, are difficult problems to address. In this paper, a three-dimensional graphics processing unit (GPU)-accelerated finite difference-smoothed particle hydrodynamics (FD-SPH) method was developed for the prediction of strongly compressible fluid flow and strong fluid-structure interactions. The conventional mesh-based finite difference method was used to simulate shock wave propagation, while the smoothed particle hydrodynamics method was employed to predict the dynamic behavior of solid materials. In addition, the immersed boundary method (IBM) was implemented in the GPU-accelerated FD-SPH solver for the boundary treatment of the interface between solid and fluid materials. Four numerical cases, namely shock-cylinder obstacle interaction, elastic panel deformation induced by shock wave propagation, the response of stainless steel tubes under internal blast loading, and the damage of blast loading on reinforced concrete slab, were conducted for verification of the GPU-accelerated FD-SPH solver. The numerical results were compared against the available experimental data, which shows that the GPU-accelerated FD-SPH solver is capable of capturing the shock wave propagation and its damage to structures very well. • A GPU accelerated coupled FD-SPH method is developed to solve strong fluid-structure interaction problems. • The immersed boundary method is used in the solver to impose boundary conditions on the fluid-structure interface. • The propagation of shock waves and its damage to the structure is well captured. [ABSTRACT FROM AUTHOR]

Structures with a partially overlapped status in water can be seen in some engineering applications, and the fluid-structure coupling vibration behavior of two partially overlapped identical plates has been studied previously through the experimental method. In this study, the added damping of the T(0,1) modes of two submerged partially overlapped plates is numerically investigated through the one-way fluid-structure interaction (FSI) method. The relevant numerical settings, like the mesh size, calculated periods, time-step size, and vibration amplitude, were tested first. Then, the numerical results were compared with experimental results, and good agreements were found. Finally, numerical results were analyzed. The vibration status of two plates in the joint abutting area or the overlapped area has an important influence on the added mass variation. When the added mass is higher, the phase difference between modal force and vibration displacement is also greater, which is the main reason for the higher added damping. The relationship between the phase difference and the frequency in water can be approximately fitted to a straight line, which can probably be used to predict the added damping variations caused by fluid boundary changes of submerged structures. [ABSTRACT FROM AUTHOR]

Most metal turning processes utilize cutting fluids. Despite extensive experimental and analytical studies, the mechanisms of chip formation under consideration of a cutting fluid are still not entirely understood. Due to fluid-structure interaction, simulating wet cutting processes for an extended duration has not been feasible. The primary objective of this study is to utilize a simulation approach to provide additional information about the wet chip formation process in contrast to measurement methods, with a view to drawing conclusions. As methodology the Finite-Pointset-Method (FPM) is employed to simulate the chip formation process for dry, flood and specifically high-pressure cooling conditions during machining of carbon steel C45 as well as nickel-based alloy Inconel 718. Due to the increased relative velocity between workpiece and cutting fluid with the use of high-pressure cooling compared to flood cooling, numerical stability issues are present. Initially, the modeling approach to handle high-pressure cooling conditions is described and validated by an impact test. Subsequently the cutting simulation model is presented in detail and verified by measurements. The simulation results of stress, temperature and plastic strain rate fields are used to elucidate the observed discrepancies between various cutting fluid strategies in detail. These findings suggest explanations for the high efficiency of high-pressure cooling such as a decline of hydrostatic stresses or activation of ductile damaging. [ABSTRACT FROM AUTHOR]

The propulsive characteristics of self-propelling 3D flexible foil are numerically studied. Two kinds of dynamic boundary techniques, namely the dynamic mesh technique and overlapping mesh technique, are used to realize the self-propulsion of flexible foil. The effects of aspect ratio (AR), characteristic thickness (d), and section shape on propulsive characteristics are numerically studied. Results demonstrate that the moving velocity increases monotonically with the consistent growth of AR, and a linear relationship is found between them. The peak value of propulsive efficiency can be acquired when AR = 1.0. Moreover, the growth of d shall produce a negative effect on moving velocity. It is suggested that the value of d should be smaller than 0.15 for the sake of acquiring high propulsive efficiency. As for the section shape effect, the foil with a rectangular shape presents the worst propulsive property, while the NACA0015 foil exhibits the best one. Furthermore, the typical vortex structures are also exhibited and analyzed. The conclusions acquired in this study are of great significance for designing a bionic underwater vehicle. [ABSTRACT FROM AUTHOR]

An approach to estimate the dynamic characteristic of multilayered three-dimensional cubic quasicrystal cylindrical shells, annular plates, and truncated conical shells with different boundary conditions is presented. These investigated structures can be in a vacuum, totally filled with quiescent fluid, and subjected to internal flowing fluid where the fluid is incompressible and inviscid. The velocity potential, Bernoulli's equation, and the impermeability condition have been applied to the shell–fluid interface to obtain an explicit expression, from which the fluid pressure can be converted into the coupled differential equations in terms of displacement functions. The state-space method is formulated to quasicrystal linear elastic theory to derive the state equations for the three structures along the radial direction. The mixed supported boundary conditions are represented by means of the differential quadrature technique and Fourier series expansions. A global propagator matrix, which connects the field variables at the internal interface to those at the external interface for the whole structure, is further completed by joint coupling matrices to overcome the numerical instabilities. Numerical examples show the correctness of the proposed method and the influence of the semi-vertical angle, different boundary conditions, and the fluid debit on the natural frequencies and mode shapes for various geometries and boundary conditions. [ABSTRACT FROM AUTHOR]

Considering the real stress and deformation state of impeller during the operation of centrifugal pump, the fluid-structure coupling numerical simulation of impeller of centrifugal pump model was carried out based on the software platform of Ansys Workbench and the computational fluid dynamics analysis software CFX. The strength of impeller of centrifugal pump under the combined action of centrifugal force and CFD pressure load was calculated. The position of the maximum stress on the impeller under the action of cyclic alternating stress during rotation is determined. Finally, nCode Designlife software was used to predict the fatigue life of the impeller. The results show that the maximum stress is located at the interface between the blade outlet edge and the cover plate, and the cyclic cyclic stress is the main cause of the fatigue damage of the impeller. The impeller meets the design of infinite life fatigue strength, and the impeller has no risk of fatigue failure. [ABSTRACT FROM AUTHOR]

AbstractThe simulation of the aortic valve (AV) remains challenging due to its geometric complexity and the multi-physics nature of the problem. In this study, we utilized COMSOL to establish a three-dimensional, three-leaflet AV fluid-structure interaction model and investigated the influence of material properties on the valve's mechanical behavior in a healthy state. The results indicated that variations in the aortic wall material model had a minor impact on AV hemodynamics. Additionally, while the linear elastic properties of the leaflets limit valve opening and closing, this material model allows for rapid assessment of AV performance within the range of material deformation. [ABSTRACT FROM AUTHOR]

An innovative concept of metabarrier is presented for seismic Rayleigh wave attenuation, which consists of a periodic array of cylindrical water tanks acting as resonant units above the soil surface. A pertinent theoretical framework is developed and implemented in COMSOL Multiphysics. The framework treats the dynamics of the water tank by a well-established three-dimensional linear, pressure-based model for fluid-structure interaction under earthquake excitation, accounting for the flexibility of the tank wall; furthermore, the soil is idealized as a homogeneous and isotropic medium. Floquet-Bloch dispersion analysis of the unit cell demonstrates the presence of relevant band gaps in the low-frequency range below 20 Hz and in the higher frequency range as well. The dispersion analysis is validated by comparison with the frequency-domain analysis of a soil domain with a finite array of water tanks. The band gaps are of interest to attenuate seismic Rayleigh waves and, more generally, Rayleigh waves caused by other ground vibration sources such as road or railway traffic. The water-tank resonant units are readily tunable by varying the water level, which allows changing opening frequencies/widths of the wave attenuation zones. This is a remarkable advantage over alternative seismic metamaterials that, in general, are not designed to be tunable. This article is part of the theme issue 'Current developments in elastic and acoustic metamaterials science (Part 2)'. [ABSTRACT FROM AUTHOR]

Cerebral aneurysms are abnormal dilations of blood vessels in the brain that have the potential to rupture, leading to subarachnoid hemorrhage and other serious complications. Early detection and prediction of aneurysm rupture are crucial for effective management and prevention of rupture-related morbidities and mortalities. This review aims to summarize the current knowledge on risk factors and predictive indicators of rupture in cerebral aneurysms. Morphological characteristics such as aneurysm size, shape, and location, as well as hemodynamic factors including blood flow patterns and wall shear stress, have been identified as important factors influencing aneurysm stability and rupture risk. In addition to these traditional factors, emerging evidence suggests that biological and genetic factors, such as inflammation, extracellular matrix remodeling, and genetic polymorphisms, may also play significant roles in aneurysm rupture. Furthermore, advancements in computational fluid dynamics and machine learning algorithms have enabled the development of novel predictive models for rupture risk assessment. However, challenges remain in accurately predicting aneurysm rupture, and further research is needed to validate these predictors and integrate them into clinical practice. By elucidating and identifying the various risk factors and predictive indicators associated with aneurysm rupture, we can enhance personalized risk assessment and optimize treatment strategies for patients with cerebral aneurysms. [ABSTRACT FROM AUTHOR]

Well workover operation in some blocks of the Tarim Basin resulted in mud leakage to the gas-producing formation, resulting in damage to gas well production. Therefore, refracturing of mud leakage wells in the future is necessary. To explore the means of refracturing to promote the recovery of gas well productivity, studying the evolution law of the production-induced stress field is necessary. Therefore, in this study, a prediction model of the production-induced stress field of fractured high-yield gas wells was established, and the evolution law of the stress field under the set production conditions of high-yield gas wells was clarified. The results show that with an increase in matrix permeability, main fracture conductivity, and natural fracture density, the decrease in the amplitude of stress decreases under the set production. At lower matrix permeability and natural fracture density, the low-stress areas on both sides and the front end of the main fracture are larger. At a higher main fracture conductivity, the low-stress area at both sides and the front end of the main fracture is larger. The change in the in situ stress of the gas well is smaller under set production than constant-pressure production. [ABSTRACT FROM AUTHOR]

The current literature analyzing the dynamic response of coupled pipelines neglects the crucial interplay between the pipelines themselves and these constraints. This overlooked interaction has substantial influence on the fluid–structure coupling response, particularly in scenarios involving continuous constraints. We focus on a piping system surrounded by compacted soil, which is regarded as unbounded homogeneous elastic soil that suffers from water hammer. This study established a one-dimensional model for water pipe-embedded compacted soil with fluid–structure–soil interaction. Taking fluid–structure–soil interaction into account, fluid–structure interactions (FSIs) include Poisson coupling, junction coupling emerging at the fluid–structure interface, and pipe–soil coupling (PSC) emerging at the pipe–soil interface. In this study, as soil is assumed to be a homogeneous, isotropic elastic material, the coupling responses are more complex than those of an exposed pipe, and the relevant mechanisms justify further exploration to obtain well-predicted results. To mathematically describe this system considering fluid–structure–soil interaction, the four-equation FSI model was modified to accommodate the piping system surrounded by unbounded homogeneous elastic soil, employing the finite volume method (FVM) as a means to tackle and solve the dynamic problems with FSI and PSC, which partitions the computational domain into a finite number of control volumes and discretizes governing equations within each volume. The results were validated by the experimental and numerical results. Then, dynamic FSI responses to water hammer were studied in a reservoir–pipe–reservoir physical system. The hydraulic pressure, pipe wall stress, and axial motion were discussed with respect to different parameters. With the PSC and FSI taken into account, fluid, soil, and pipe signals were obviously observed. The results revealed the structural and fluid modes. Dynamic responses have been proven to be difficult to understand and predict. Despite this, this study provides a tractable method to capture more accurate systematic characteristics of a water pipe embedded in soil. [ABSTRACT FROM AUTHOR]

Segmented multi-cluster fracturing is a key technology for unconventional reservoir development, and injection parameters have a significant impact on frictional resistance and fracture initiation pressure. A numerical model of dynamic fracking fracture propagation in horizontal wells was established by considering the flow distribution between the cluster perforations, the stress interference between the fractures, and the fluid-structure interaction, while the impact of various perforation parameters on the perforation friction and initiation pressure was investigated. The numerical simulation results showed that a more significant perforation density, aperture, and depth decreased the hydraulic fracture initiation pressure. The initiation pressure displayed an initial decline at a higher perforation azimuth angle, followed by an increase while exhibiting a decreasing-increasing-decreasing fluctuation trend at a higher perforation phase angle. By extracting the influence of different apertures and hole numbers on the wellbore friction, The optimization template for perforation diameter and perforation quantity corresponding to different hole friction in flow limiting fracturing is provided. This provides theoretical support for optimizing the perforation parameters of segmented cluster fracturing in horizontal wells. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive numerical investigation into the nonlinear dynamics of Dipteran-inspired flapping flight systems at low Reynolds numbers, with the goal of advancing micro aerial vehicle (MAV) design. Using a forced Duffing oscillator model to represent the wing's structural dynamics and an in-house Navier–Stokes solver based on the immersed boundary method for aerodynamic forces, we capture the intricate fluid–structure interactions (FSI) of the system. Our results reveal insights into the stability and chaotic behavior of the flapping wing system, emphasizing the critical role of viscous effects. The complex interplay between the wing's nonlinear response and aerodynamic loads leads to diverse oscillatory patterns and transitions to chaos. By varying the actuation force as a bifurcation parameter, the system transitions from periodic behavior to sustained chaos through intermediate quasi-periodic and transient chaotic states. These findings highlight the importance of accurately modeling FSI to enhance MAV performance, providing valuable insights into their design and for stability and maneuverability in bio-inspired flapping flight systems. [ABSTRACT FROM AUTHOR]

In equipment within the aviation and marine industries, aerodynamic and hydrodynamic noises generated by the coupling effect between moving structures (such as equipment shells, landing gears, blades, etc.) and fluid media are ubiquitous. These noises significantly impact the noise levels of the equipment and its surrounding environment, posing threats to the health of users and organisms in the environment. While existing noise calculation methods effectively address aerodynamic and hydrodynamic noises from fixed structures under uniform incoming flow conditions, few literatures delve into the computational methods for aerodynamic and hydrodynamic noises arising from the interaction between moving structures and fluid media. To calculate fluid noises induced by structural vibrations and motions, this paper proposes an immersed boundary method for fluid–structure–acoustic interactions with moving structures. This method concurrently employs the Navier–Stokes equation and wave equation to describe the time-averaged quantities and fluctuating variables of the fluid, taking into account the influence of non-uniform fluids during sound propagation. Based on this methodology, noise tests and numerical calculations were conducted on vibrating cylindrical shells, along with fluid–structure–acoustic coupling calculations for linearly moving cylinders in static fluids. These examples validate the effectiveness and accuracy of the proposed method in simulating the generation and propagation processes of radiation noise and flow-induced noise caused by structural motion. [ABSTRACT FROM AUTHOR]

This study employs a high-fidelity numerical approach to simulate fluid–structure interaction phenomena for the dynamic response of flexible hyperelastic morphing wing structures under low aerodynamic loads. The computations are performed using the open-source solids4Foam toolbox, employing a partitioned two-way fluid–structure interaction approach with a finite volume solver for both fluid and solid. The considered morphing wing is divided into a flexible and a rigid segment, with the flexible segment featuring a 60% chord length and being made of a hyperelastic rubber-like material. The concept of damping is incorporated into the solid momentum balance equation as a virtual force that opposes the velocity of the structure. Damping is employed to disperse energy from the system, hence mitigating the oscillations and reducing computational time. To understand morphing wing aerodynamics and aeroelasticity behavior, a series of tests are conducted at low and medium Reynolds numbers, specifically 2 × 10 5 and 5 × 10 5 . The results show that, for low Reynolds number, the morphing structure has a negligible impact on aerodynamic behavior. However, at higher Reynolds numbers, morphing results in improved aerodynamic efficiency at low angles of attack. Overall, the study highlights the aero-structural behavior of hyperelastic morphing wings and their potential for developing efficient and adaptive wing structures, highlighting their promise for future aircraft design innovations. [ABSTRACT FROM AUTHOR]

Simulating the free decay motion and wave radiation from a heaving semi-submerged sphere poses significant computational challenges due to its three-dimensional complexity. By leveraging axisymmetry, we reduce the problem to a two-dimensional simulation, significantly decreasing computational demands while maintaining accuracy. In this paper, we exploit axisymmetry to perform a large ensemble of Computational Fluid Dynamics (CFDs) simulations, aiming to evaluate and maximize both accuracy and efficiency, using the Reynolds Averaged Navier–Stokes (RANS) solver interFOAM, in the opensource finite volume CFD software OpenFOAM. Validated against highly accurate experimental data, extensive parametric studies are conducted, previously limited by computational constraints, which facilitate the refinement of simulation setups. More than 50 iterations of the same heaving sphere simulation are performed, informing efficient trade-offs between computational cost and accuracy across various simulation parameters and mesh configurations. Ultimately, by employing axisymmetry, this research contributes to the development of more accurate and efficient numerical modeling in ocean engineering. [ABSTRACT FROM AUTHOR]

The focus of this paper is the optimization of a ship propeller with regard to its acoustic emission, taking advantage of its flexible material. For this purpose, an optimization method is developed based on a partitioned approach for the simulation of the fluid-structure problem. A boundary element method is applied on the hydrodynamic side whilst the structural problem is solved via a finite element approximation. The approach is validated referring to the hydrodynamic performance of model propellers at different stiffness values. Two optimization approaches are applied. In the first approach, only the hydrodynamic part of the problem is simulated. The second approach considers the fully coupled fluid-structure interaction. The optimized propeller is simulated using a partially nonlinear model for sheet cavitation to evaluate the noise level. Finally, the results are compared with those of the reference propeller. [ABSTRACT FROM AUTHOR]

The responses of sandwich cylindrical shells containing fluid to free vibrations and low-velocity impact were studied. The high-order shear deformation theory and Bernoulli's equation for the structure-fluid interface were used. To solve the equations obtained and validate the results, the Galerkin method and Abaqus finite element software were employed. The main innovation of this research is the calculation of the effective mass of the top layer and the entire sandwich cylindrical shell containing fluid using displacement field relations, their equivalent density, and indentation force due to impact. In addition, to calculate the impact force and the structure-fluid interaction, a two-degree-of-freedom model of mass, spring, and damper with the effect of the crushing resistance of the core was used. The results show that the fluid is an important and effective factor in calculating the natural frequency and low-velocity impact on the structure. The presence of fluid reduces the fundamental natural frequency of the sandwich cylindrical shell by 69%. Parameters such as core and layer thickness, length, and radius of the sandwich cylindrical shell, presence of the fluid, various boundary conditions, wave number, fiber orientation angles, velocity, and mass of the impactor are essential and influential factors in studying vibrations, impact, and optimal design of structures. [ABSTRACT FROM AUTHOR]

The operation of wind turbines involves a complex interaction between aerodynamics, structural mechanics, and control systems. However, the control system is frequently overlooked. To investigate the impact of the control system on the aerodynamic characteristics and elastic deformations of wind turbines, this paper initially integrates the control system into the blade element momentum theory (BEMT) for calculating aerodynamic forces. Subsequently, the control system is incorporated into fluid-structure interaction (FSI) calculations to assess its influence on the overall performance of the turbine. The control system employs variable speed and pitch control, while the structural dynamics are modeled using the Euler-Bernoulli beam theory. When the control system is integrated with blade element momentum theory to calculate the aerodynamic forces of the wind rotor, it is observed that, below the rated wind speed, a portion of the torque error is transferred to the rotor speed. In contrast, above the rated wind speed, the entire torque error is transferred to the blade pitch angle (BPA). Crucially, when the control system is integrated, the rotor speed and BPA are no longer treated as known parameters. This approach enables the prediction of aerodynamic characteristics of the wind rotor, particularly under complex wind speed profiles. The control system exerts a significant influence on the FSI results, particularly in the range of wind speeds that correspond to larger blade deformations. This work can provide a reference for the calculation of aerodynamic characteristics and FSI of wind turbines under complex wind conditions. [ABSTRACT FROM AUTHOR]

Bicuspid aortic valve (BAV) is a common congenital malformation of the aortic valve with various structural characteristics. Different types of BAV can cause secondary aortic diseases, including calcific aortic valve stenosis and aortic dilation, although their pathogenesis remains unclear. In this study, we first established patient-specific BAV simulation models and silicone models (Type 0 A-P, Type 1 R-N, and Type 1 L-R) based on clinical computed tomography angiography (CTA) and pressure data. Next, we applied a research method combining fluid-structure interaction (FSI) simulation and digital particle image velocimetry (DPIV) experiment to quantitatively analyze the hemodynamic, structural mechanical, and flow field characteristics of patients with different BAV types. Simulation-based hemodynamic parameters and experimental results were consistent with clinical data, affirming the accuracy of the model. The location of the maximum principal strain in the patient-specific model was associated with the calcification site, which characterized the mechanism of secondary aortic valve stenosis. The maximum wall shear stress (WSS) of the patient-specific model (>67.1 Pa) exceeded 37.9 Pa and could cause endothelial surface injury as well as remodeling under long-term exposure, thus increasing the risk of aortic dilation. The distribution of WSS was mainly caused by BAV type, resulting in different degrees of dilation in different parts guided by the type. The patient-specific model revealed a maximum viscous shear stress (VSS) value of 5.23 Pa, which was smaller than the threshold for shear-induced hemolysis of red blood cells (150 Pa) and platelet activation (10 Pa), but close to the threshold for platelet sensitization (6 Pa). The results of flow field characteristics revealed a low risk of hemolysis but a relative high risk of thrombus formation in the patient-specific model. This study not only provides a basis for future comprehensive research on BAV diseases, but also generates relevant insights for theoretical guidance for calcific aortic valve stenosis and aortic dilation caused by different types of BAV, as well as biomechanical evidence for the potential risk of hemolysis and thrombus formation in BAV, which is of great value for clinical diagnosis and treatment of BAV. [ABSTRACT FROM AUTHOR]

Plate-type fuel elements, widely used in high flux reactor (HFR), may experience collapse or vibration under high coolant flow rates. The study examined the behaviors of curved fuel plates under varying coolant velocities. The deformations of curved plates with varying curvature radii and flat-plate assemblies were computed to facilitate comparison. The fluid domain was simulated using Ansys Fluent, while the solid domain was analyzed using Ansys Mechanical. The study employed a partitioned, two-way, and explicit coupling strategy. The simulation results have shown that the critical velocity for assemblies of curved plates is 20 m/s, whereas for flat plates it is 6 m/s. As the curvature radius or width increases, the plates become increasingly susceptible to collapse. The critical velocity is associated with the nonlinearity between the maximum plate deflections and the square of flow velocities. It also involves plate deflections that extend from the leading edges to the entire length of the fuel at the critical velocity. Under axial flow conditions, the deflection directions of multiple curved plates exhibit regular patterns. The leading edges of the plates adjacent to the walls deflect towards the walls, while the adjacent plates deflect in opposite directions. [ABSTRACT FROM AUTHOR]

An improved data-driven glottal flow model for fluid-structure interaction (FSI) simulation of the vocal fold vibration is proposed in this paper. This model aims to improve the prediction performance of the previously developed deep neural network (DNN) based empirical flow model (EFM) 1 on accuracy and efficiency. A Seq2Seq long short-term memory (LSTM) network is employed in the present model to infer the flow rate and pressure distribution from the subglottal pressure and cross-section area distribution of the glottis. The training data is collected from the generalized glottal shape library generated in Zhang et al. 1 Compared to the EFM, the present model not only discards the time-consuming optimization process, but also drastically reduces the errors, therefore the prediction performance can be greatly improved. The present model is evaluated by coupling with a solid dynamics solver for FSI simulation, and the results demonstrate a great improvement on accuracy and efficiency. [ABSTRACT FROM AUTHOR]

Direct dry-cooled power plants typically operate numerous large-diameter axial flow fans in air-cooled condensers (ACCs) to facilitate the condensation of steam in the plant's thermodynamic cycle. Enhanced fan efficiency may, at scale, lead to significant parasitic power reductions and subsequent increases in plant power output. The performance of these fans may be increased by adding blade-tip modifications, which act to control blade-tip leakage flow. Previous studies have shown that manipulating the tip leakage vortex (TLV) increases the blade-to-air momentum transfer and stabilizes the air flow structures as it traverses the fan blade. This paper takes a step toward the development of improved tip vortex manipulators for an ACC fan. Three-dimensional computational fluid dynamics (CFD) simulations, and experimental testing of the modified and unmodified fan within an ISO test facility are performed. The results are then utilized to assess the accuracy of the simulation model, visualize the manipulated flow structures at the blade tip, and ultimately quantify the effect of the endplate designs on fan performance. Excellent correlation between numerical and test results for the unmodified fan is observed, and the benefit of blade-tip modification on fan performance is again confirmed experimentally. The simulation model, however, fails to predict improvements in fan performance under modification, and simulated tip leakage flows are investigated for clarification. It is hypothesized that deflection of tip endplates under operation account for differences between simulation and experiment, and that fluid-structure interaction analyses could potentially resolve discrepancies. [ABSTRACT FROM AUTHOR]