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Rogue waves and breathers emerge as significant solitons, result from ubiquitous nonlinear effects of dynamics in the natural world, science and engineering. In this paper, we study the AB system, a model derived from a two-layer fluid that is widely used to investigate nonlinear fluid dynamics. We use the Darboux transformation to construct analytical solutions for higher-order hybrid rogue waves and breathers, which are expressed by symmetric algebraic matrices. We use these solutions and the spectrum parameters to explore the complex interaction dynamics of the hybrid rogue waves and breathers. We find that the interactions cause significant changes in the phases and shapes. Moreover, we discover an interesting phenomenon: the collisions between the rogue waves and breathers are semi-elastic, meaning that only the phases of the rogue waves change, while the speeds, shapes and phases of the breathers remain the same, before and after the collisions. This study provides new insights into the dynamics of the AB system, and helps us understand nonlinear phenomena in various two-layer fluid systems. [ABSTRACT FROM AUTHOR]

The aim of this work is to present a parallel solver for a formulation of fluid–structure interaction (FSI) problems which makes use of a distributed Lagrange multiplier in the spirit of the fictitious domain method. The fluid subproblem, consisting of the non-stationary Stokes equations, is discretized in space by Q 2 – P 1 finite elements, whereas the structure subproblem, consisting of the linear or finite incompressible elasticity equations, is discretized in space by Q 1 finite elements. A first order semi-implicit finite difference scheme is employed for time discretization. The resulting linear system at each time step is solved by a parallel GMRES solver, accelerated by block diagonal or triangular preconditioners. The parallel implementation is based on the PETSc library. Several numerical tests have been performed on Linux clusters to investigate the effectiveness of the proposed FSI solver. [ABSTRACT FROM AUTHOR]

This paper analyzes nonlinear free vibration of plates that move axially and in partial contact with liquid. The von Kármán nonlinear plate theory is employed in the theoretical model. The fluid is characterized as an ideal fluid and represented using the velocity potential and Bernoulli's equation. The fluid pressure exerted on the plate is equivalent to a virtual additional mass, which is considered as part of the total mass of the structure. Employing the Hamilton's principle to derive the immersed moving plates' governing equations. Afterward, the nonlinear frequencies of plates moving axially and contacting with liquid are evaluated by the Chebyshev collocation method combined with the direct iterative technique. The results indicate that the Chebyshev collocation method exhibits excellent convergence and exceptional accuracy. It has been observed that the immersed moving plates' nonlinear frequencies gradually increase with the decrease of the axial velocity. The increase of immersion level or fluid density reduces nonlinear frequencies, but has little influence on nonlinear to linear frequency ratios. [ABSTRACT FROM AUTHOR]

The problem of water wave interactions with marine structures, involving complex nonlinear characteristics such as large deformation of free-surface and violent structural motion, has been the focus and challenge of research in naval, coastal and ocean engineering. Recently, the δ -SPH C model has been successfully applied in numerical wave flumes despite some minor flaws in energy conservation. In the present study, a robust δ -SPH C with a better property regarding energy conservation is further formulated to simulate the hydrodynamic problems of various nonlinear water waves and structures. Three numerical benchmarks, i.e., the coupling motion between second-order Stokes waves, solitary waves, focused waves and structures are implemented to validate the accuracy and stability of the fluid–structure interaction (FSI) model, respectively. Based on the numerical results, the strengths and weaknesses between the δ -SPH, original and improved δ -SPH C models in simulating the FSI problems are discussed. It is demonstrated that the present scheme performs fairly well in modeling nonlinear water wave–structure interactions. • A robust δ -SPHC model is further formulated to model the nonlinear water wave interactions with structures. • A comparison to numerical simulations of different benchmarks between the two δ -SPHC models is conducted. • The SPH scheme is demonstrated to predict the complex wave–structure interactions in ocean engineering. [ABSTRACT FROM AUTHOR]

Liquid sloshing is a typical problem of free surface flow in a number of engineering applications. The efficient simulation of liquid sloshing, particularly the large deformation and breakup of free surface, is a challenge for numerical methods. This paper presents a numerical method based on smoothed particle hydrodynamics with adaptive spatial resolution (SPH-ASR) for liquid sloshing. The SPH-ASR method can adaptively adjust the spatial resolution based on the distance to the free surface and the moving boundary. The numerical method was validated against experimental results from literature. Then the SPH-ASR method was applied to study the liquid sloshing problem in a prismatic tank and a rectangular tank. The effects of liquid fill level, external excitation frequency and amplitude on liquid sloshing were investigated. The pressure at different points on the tank wall and the total moment on the rotating shaft of the tank were compared and analyzed. [ABSTRACT FROM AUTHOR]

With the increasing demand of large scale computation, multi-resolution particle methods have been paid much attention by many researchers. In multi-resolution method, high resolution is applied in local area to reduce the whole computational costs and maintain the local accuracy. However, there are still many challenges in the stability and accuracy of multi-resolution particle methods. In this research, an efficient variable particle size (VSP) multi-resolution method, using particle splitting and coalescing techniques, is developed in moving semi-implicit particle (MPS) method. Particles split or coalesce in dynamic five steps to avoid particle overlap and clustering. The mixed splitting mechanism by combining hexagonal splitting pattern and pair splitting pattern are proposed in the five-step splitting algorithm. Pair splitting and coalescing techniques with variable particle size are proposed to strictly ensure the conservation of mass and momentum and avoid particle clustering. To solve the non-linear fluid-structure interaction problem, the VSP algorithm is introduced in MPS-DEM method. The numerical results are compared with the analytical solutions and experimental results. It shows that the proposed VSP algorithm cannot only maintain the local accuracy, but also improve the computational efficiency by avoiding unnecessary chain operations between particle splitting and coalescing. [ABSTRACT FROM AUTHOR]

• A Riemann SPH-Hamiltonian SPH coupled hydroelastic FSI solver is proposed with four refined schemes. • A conservation-enforcing limiter to enforce the conservation of density diffusion in global scale. • A dynamic Pressure-based reconstruction for enhanced reconstruction of physical quantities. • A modified Velocity-divergence error mitigating scheme for enhanced incompressibility. • A Riemann term for stabilisation of the structural momentum equation. The paper presents a novel Lagrangian meshfree computational solver for simulation of hydroelastic fluid-elastic structure interaction (FSI) problems. An explicit Smoothed Particle Hydrodynamics (SPH) method, referred to as Riemann SPH, is adopted as the fluid model, and a SPH method within the Hamiltonian framework, namely Hamiltonian SPH (HSPH), is considered as the structure model. A two-way coupling between fluid and structure models is performed in a consistent manner, resulting in a coupled RSPH-HSPH hydroelastic FSI solver. For enhancement of accuracy and robustness of the proposed FSI solver, four refined schemes are incorporated for the fluid and structure models. These four refined schemes include (i) a novel dissipation limiter in the fluid's continuity equation for enforcing the volume conservation, (ii) a refined reconstruction of the quantities in Riemann SPH in the presence of a potential field, (iii) a modified velocity-divergence error mitigation term in the fluid's momentum equation for enhanced satisfaction of the incompressibility condition, and (iv) a Riemann diffusion term in the structural momentum equation for enhanced stability and robustness. Validations of the proposed FSI solver are carried out through a series of fluid, structure and FSI benchmark tests. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to report the study of a fluid buoy system that includes wave effects, with particular emphasis on validating the numerical results with experimental data. Design/methodology/approach: A fluid–solid coupled algorithm is proposed to describe the motion of a rigid buoy under the effects of waves. The Navier–Stokes equations are solved with the open-source finite volume package Code Saturne, in which a free-surface capture technique and equations of motion for the solid are implemented. An ad hoc experiment on a laboratory scale is built. A buoy is placed into a tank partially filled with water; the tank is mounted into a shake table and subjected to controlled motion that promotes waves. The experiment allows for recording the evolution of the free surface at the control points using the ultrasonic sensors and the movement of the buoy by tracking the markers by postprocessing the recorded videos. The numerical results are validated by comparison with the experimental data. Findings: The implemented free-surface technique, developed within the framework of the finite-volume method, is validated. The best-obtained agreement is for small amplitudes compatible with the waves evolving under deep-water conditions. Second, the algorithm proposed to describe rigid-body motion, including wave analysis, is validated. The numerical body motion and wave pattern satisfactorily matched the experimental data. The complete 3D proposed model can realistically describe buoy motions under the effects of stationary waves. Originality/value: The novel aspects of this study encompass the implementation of a fluid–structure interaction strategy to describe rigid-body motion, including wave effects in a finite-volume context, and the reported free-surface and buoy position measurements from experiments. To the best of the authors' knowledge, the numerical strategy, the validation of the computed results and the experimental data are all original contributions of this work. [ABSTRACT FROM AUTHOR]

• A multi-resolution DFPM-PD model is developed for FSI problems. • The DGP scheme for interface processing comprises common smoothing length and TIC technique. • A particle-to-particle contact model for collisions between structures. • The model's accuracy and potential are demonstrated through several benchmark tests and a tsunami-induced structural failure case. • The model significantly reduces computational costs without compromising accuracy. This paper presents an accurate and efficient multi-resolution model for reproductions of fluid-structure interaction (FSI) issues involving intricate fluid flow phenomena, as well as structural deformation and failure. The proposed model comprises two modules, i.e., the decoupled finite particle method (DFPM) module for the solution of fluid flow, and the peridynamics (PD) module for simulating motion, deformation, fracture, and contact of structures. By employing distinct particle spacing and time step increments for the two modules, the model achieves spatial-temporal multi-resolution discretization. To address the fluid-structure interfacial region accurately, a disguised ghost particle (DGP) coupling scheme, incorporating a common smoothing length and a tensile instability control (TIC) technique, is developed. The particle inconsistency at the fluid-structure interface is resolved through the use of ghost particles and DFPM approximation, thus enabling more precise computation of interaction forces. Furthermore, a contact model is incorporated into the PD module to reflect contact interactions between solid structures. A set of benchmarks are investigated to validate the accuracy, robustness as well as efficiency of the presented multi-resolution model, and then it is further employed to simulate structural failure due to tsunami waves, which demonstrates its capability of handling engineering FSI problems with structural failure. [ABSTRACT FROM AUTHOR]

The applications of the arbitrary Lagrangian-Eulerian (ALE) method on the regularized boundary integral method (RBIM) for simulating water wave transformation over complex topography and wave-structure interaction based on fully nonlinear potential theory are presented. When solving the boundary integral equation (BIE), RBIM computes the singular integrals of the source and doublet functions through the coordinate transformation. Any high-order quadrature can be directly applied as collocation nodes hence spatial discretization is avoided. Through the same technique, the numerical near singularities of the source and doublet integrals can be handled. The ALE approach is adopted to avoid distorted nodal distribution, which often results from the free surface of highly nonlinear water waves, and to keep the convenience of the application of free-surface boundary conditions. The ALE-RBIM and the Newmark method are coupled iteratively for computing structural dynamics undergoing hydrodynamic excitations. The numerical method is validated through three examples: the run-up and reflection of a solitary wave; the periodic wave propagation over complex topography; and the roll motion of a hinge-fixed floating structure undergoing wave excitations. Several important wave features are captured. The wave-structure interaction is characterized. The advantages of ALE-RBIM over MEL-BEM are shown. Correlations between numerical results and experimental measurements are presented. [ABSTRACT FROM AUTHOR]

This study uses the lattice Boltzmann method to research the heat transfer features of Pseudoplastic fluid in a microchannel. The Power law model is intended to simulate non-Newtonian fluids. The fluid slip on the surface is applied to the hydrophobic surfaces, and also the viscose dissipation term is considered in the governing equations. The problem is presented for Reynolds numbers 20 and 30, slip coefficients 0.01, 0.02, and 0.03, and Prandtl numbers 1 and 6.2. Results reveal that the average Nusselt number in the microchannel with a power index of 0.5 of non-Newtonian fluid is more significant than Newtonian fluid. It was seen that viscose dissipation impact on the average Nusselt number is insignificant. [ABSTRACT FROM AUTHOR]

• A zonal free element method is proposed which fully couples velocity and pressure. • The proposed can significantly improve the convergency by the fully couple way. • The nonphysical oscillation caused by buoyance and pressure is avoided. • The results of the conjugate heat transfer in fluid and solid well match that of experiments. Recently, the zonal free element method (ZFREM) is proposed to solve thermal and mechanical problems. In this paper, we developed a novel method for the conjugate heat transfer in fluid and solid based on ZFREM. The proposed method solves velocity and pressure FFIGsimultaneously and significantly promotes the convergency characteristics. Using the proposed method, we solved the natural convection and forced heat transfer problems in the fluid-solid interaction systems. The results computed with the proposed method are examined by the available results in literature and experiments. The numerical examples illustrate that the proposed method is efficient and robust. [ABSTRACT FROM AUTHOR]

The objective of this study is to propose a new methodology for the time-domain analysis of a 2D dam-reservoir system, which considers the effects of fluid-structure interaction. The proposed method involves combining the Radial Basis Function based Differential Method (RBF-DQM) for the fluid domain with the Finite Element Method (FEM) for the solid domain. This approach is referred to as the decoupled Coupled RBF-DQM-FEM method. The RBF-DQM method is a meshless technique that utilizes Thin Plate Splines (TPS) as the test function to achieve high accuracy without requiring additional parameters. The compatibility conditions are imposed iteratively along the dam-reservoir interface to couple the solutions obtained from the fluid and solid domains. This study presents several examples in the time domain to demonstrate the accuracy and performance of the proposed method. The numerical simulations show excellent agreement with other benchmark solutions. [ABSTRACT FROM AUTHOR]

Purpose: Atherosclerosis tends to occur in the distinctive carotid sinus, leading to vascular stenosis and then causing death. The purpose of this paper is to investigate the effect of sinus sizes, positions and hematocrit on blood flow dynamics and heat transfer by different numerical approaches. Design/methodology/approach: The fluid flow and heat transfer in the carotid artery with three different sinus sizes, three different sinus locations and four different hematocrits are studied by both computational fluid dynamics (CFD) and fluid-structure interaction (FSI) methods. An ideal geometric model and temperature-dependent non-Newtonian viscosity are adopted, while the wall heat flux concerning convection, radiation and evaporation is used. Findings: With increasing sinus size, the average velocity and temperature of the blood fluid decrease, and the area of time average wall shear stress (TAWSS)with small values decreases. As the distances between sinuses and bifurcation points increase, the average temperature and the maximum TAWSS decrease. Atherosclerosis is more likely to develop when the sinuses are enlarged, when the sinuses are far from bifurcation points, or when the hematocrit is relatively large or small. The probability of thrombosis forming and developing becomes larger when the sinus becomes larger and the hematocrit is small enough. The movement of the arterial wall obviously reduces the velocity of blood flow, blood temperature and WSS. This study also suggests that the elastic role of arterial walls cannot be ignored. Originality/value: The hemodynamics of the internal carotid artery sinus in a carotid artery with a bifurcation structure have been investigated thoroughly, on which the impacts of many factors have been considered, including the non-Newtonian behavior of blood and empirical boundary conditions. The results when the FSI is considered and absent are compared. [ABSTRACT FROM AUTHOR]

Purpose: There are three purposes in this paper: to verify the importance of bi-directional fluid-structure interaction algorithm for centrifugal impeller designs; to study the relationship between the flow inside the impeller and the vibration of the blade; study the influence of material properties on flow field and vibration of centrifugal blades. Design/methodology/approach: First, a bi-directional fluid-structure coupling finite element numerical model of the supersonic semi-open centrifugal impeller is established based on the Workbench platform. Then, the calculation results of impeller polytropic efficiency and stage total pressure ratio are compared with the experimental results from the available literature. Finally, the flow field and vibrational characteristics of 17-4PH (PHB), aluminum alloy (AAL) and carbon fiber-reinforced plastic (CFP) blades are compared under different operating conditions. Findings: The results show that the flow fields performance and blade vibration influence each other. The flow fields performance and vibration resistance of CFP blades are higher than those of 17-4PH (PHB) and aluminum alloy (AAL) blades. At the design speed, compared with the PHB blades and AAL blades, the CFP blades deformation is reduced by 34.5% and 9%, the stress is reduced by 69.6% and 20% and the impeller pressure ratio is increased by 0.8% and 0.14%, respectively. Originality/value: The importance of fluid-structure interaction to the aerodynamic and structural design of centrifugal impeller is revealed, and the superiority over composite materials in the application of centrifugal impeller is verified. [ABSTRACT FROM AUTHOR]

This paper presents a novel interface technique employing Artificial Neural Networks (ANN) for efficient data transfer between incompressible fluid and deformable solid domains in a partitioned fluid–structure interaction (FSI) framework. Governing differential equations (GDE) with potential flow assumptions are solved to obtain pressure values at computational nodes in the fluid domain. Pressure values are then used to train an ANN-based model to interpolate pressure loads for application at non-collocated nodes on the solid boundary. Both finite element method (FEM) and meshfree element free Galerkin (EFG) formulations are used to calculate the solid deformation. Proposed methodology is applied to solve a two-dimensional (2D) unidirectional flow problem, consisting of a flexible cantilever beam immersed in a laminar, steady, and inviscid fluid. Overwhelming mathematical intricacies of computational solvers are avoided for the sake of simplistic interface treatment, flux transfer and associated phenomena. Dedicated partitioned solvers are developed for both solid and fluid domains, which are individually benchmarked for established problems from the literature. The presented ANN-based interpolation scheme provides an alternative to higher-order polynomial algorithms at the interface boundary. The proposed scheme is simple to employ, computationally efficient, and offers competitive accuracy as well as stability. • A novel ANN-based interface coupling approach for partitioned FSI problems. • Separate solvers, employing FDM for fluid domain, and FEM/EFG for solid domain. • Partitioned solvers are coupled at interface using ANN-based approximation function. • Steady unidirectional (one-way) FSI to couple FDM-ANN-FEM and FDM-ANN-EFG solvers. • ANN interpolate pressure from fluid to solid, better than polynomial-based fitting. • A generic ANN framework, extendable to problems with large deformations and velocities. [Display omitted] [ABSTRACT FROM AUTHOR]

Purpose: This study aims to evaluate blast loads on and the response of submerged structures. Design/methodology/approach: An arbitrary Lagrangian–Eulerian method is developed to model fluid–structure interaction (FSI) problems of close-in underwater explosions (UNDEX). The "fluid" part provides the loads for the structure considers air, water and high explosive materials. The spatial discretization for the fluid domain is performed with a second-order vertex-based finite volume scheme with a tangent of hyperbola interface capturing technique. The temporal discretization is based on explicit Runge–Kutta methods. The structure is described by a large-deformation Lagrangian formulation and discretized via finite elements. First, one-dimensional test cases are given to show that the numerical method is free of mesh movement effects. Thereafter, three-dimensional FSI problems of close-in UNDEX are studied. Finally, the computation of UNDEX near a ship compartment is performed. Findings: The difference in the flow mechanisms between rigid targets and deforming targets is quantified and evaluated. Research limitations/implications: Cavitation is modeled only approximately and may require further refinement/modeling. Practical implications: The results demonstrate that the proposed numerical method is accurate, robust and versatile for practical use. Social implications: Better design of naval infrastructure [such as bridges, ports, etc.]. Originality/value: To the best of the authors' knowledge, this study has been conducted for the first time. [ABSTRACT FROM AUTHOR]

Simulating hemodynamic quantities such as pressure and velocity are of great interest to clinicians to aid in surgical planning. To accurately simulate modifications to a region of vasculature, the entire system must be modeled. To facilitate this, a localized Radial-Basis Function (RBF) collocation Meshless flow solver is developed and tightly coupled to a 0D Lumped-Parameter Model (LPM) for solution of the peripheral circulation. The Meshless solver uses localized RBF collocations at data points that are automatically generated according to the geometry. The incompressible flow equations are updated by an explicit time-marching scheme based on a pressure-velocity correction algorithm. The inlets and outlets of the domain are tightly coupled with the LPM which contains elements that draw from a fluid-electrical analogy such as resistors, capacitors, and inductors that represent the viscous resistance, vessel compliance, and flow inertia, respectively. The localized RBF Meshless approach is well-suited for modeling complicated non-Newtonian hemodynamics due to ease of spatial discretization, ease of addition of multi-physics interactions such as fluid-structure interaction of the vessel wall, and ease of parallelization for fast computations. This work introduces the tight coupling of Meshless methods and LPMs for fast and accurate hemodynamic simulations. [ABSTRACT FROM AUTHOR]

The fluid flow inside the chamber with a moving wall is simulated by developed Dissipative Particle Dynamics (DPD) method which implies the developed molecular dynamics (MD) appraoch. In this benchmark problem, the chamber is filled with a fluid with a certain initial temperature and its cover is moving at a constant speed. One of the most important issues in DPD method, is creating solid walls and then applying related boundary conditions. Hence by freezing several layers of DPD particles, solid walls were created to prevent DPD particles from leaving the area. Then, by applying the boundary condition of parallel reflection, the penetration of fluid particles into the solid wall was prevented, and the no-slip condition was applied to the walls. Next, the effect of parameters such as initial distribution of fluid particles, their initial velocity, geometry of the problem, boundary conditions, Reynolds number and different weighting functions, were investigated. It was showed that increasing Reynolds number to more than 800 in addition to eliminating the incompressibility property caused particles exit from the solution domain and diverge. It is also possible to increase the Schmidt number of DPD fluid by applying a suitable weighting function. [ABSTRACT FROM AUTHOR]

A recent study conducted by researchers at RWTH Aachen University in Germany focused on the influence of the mitral valve on ventricular blood flow in relation to cardiac function. The study compared five different mitral valve models, ranging from simple to complex, to evaluate their impact on intraventricular flow features. The findings suggest that while the one-way fluid-structure interaction (FSI) model provides the most detailed flow information, it also comes with higher numerical costs and implementation challenges. The study's benchmark setup aims to facilitate further testing and expansion of mitral valve modeling approaches within the scientific community. [Extracted from the article]

A recent study conducted at Florida International University focused on biomarkers for calcific aortic valve disease (CAVD), which is a prevalent subset of heart disease. The researchers aimed to identify parameters that could be used to track the disease in its early stages. They tested three valve groups and found that tracking hemodynamics, specifically time-averaged wall shear stress (TAWSS), may be a viable biomarker for early-stage CAVD tracking. This research provides valuable insights for monitoring patients before they require aortic valve replacement surgery. [Extracted from the article]

A preprint abstract from biorxiv.org discusses the relationship between subendothelial calcification and the development of atherosclerosis. The study used mice overexpressing tissue-nonspecific alkaline phosphatase (TNAP) in endothelial cells as a model of calcification. The researchers found that subendothelial calcification increased the severity of aortic atherosclerosis in the mice and created areas of reduced wall shear stress (WSS), which led to increased uptake of low-density lipoprotein (LDL) near calcified lesions. The study also found that internal elastic lamina (IEL) calcification was prevalent in older adults and inversely correlated with arterial diameter in humans. However, it is important to note that this preprint has not been peer-reviewed. [Extracted from the article]

A new report from the University of Bristol in the United Kingdom explores the static and dynamic aeroelasticity of Fish Bone Active Camber (FishBAC) aerofoils. The study develops a two-dimensional coupled fluid-structure interaction model to investigate the aerodynamic efficiency of the FishBAC concept. The research finds that increasing the pulley rotational angle reduces the zero-lift angle of attack, while a shorter morphing region closer to the trailing edge generates a larger lift coefficient. Flutter occurs with an increase in air speed, and moving the morphing region closer to the leading edge increases the critical flutter speed. The study provides valuable insights into aerospace research and was supported by the Engineering & Physical Sciences Research Council. [Extracted from the article]

A new report discusses research findings on atherosclerosis, focusing on the investigation of arterioles using mathematical modeling techniques. The study aims to understand the flow characteristics and stress and strain distributions in the intima layer of arterioles, including coronary, renal, cerebral, mesenteric, and pulmonary arteries, under gravitational forces. The research concludes that a thorough understanding of stress distribution is crucial for developing targeted therapies to reduce vascular health problems, as the stress in the post-stenosis region significantly affects the endothelial layer. The study provides valuable insights into arteriolar atherosclerosis and its implications for cardiovascular health. [Extracted from the article]

New research from the Indian Institute of Technology (IIT) Madras explores the influence of wall thickness on the rupture risk of a patient-specific cerebral aneurysm. The study finds that thin-walled regions of an aneurysm are more vulnerable to rupture, and understanding the correlation between wall thickness and wall stresses can improve prediction using fluid-structure interaction tools. The research suggests that modeling aneurysmal wall thickness reconstruction based on in vivo conditions is an effective approach. The study concludes that a variable wall thickness model is appropriate, as patient-specific wall thickness information is currently only available retrospectively. [Extracted from the article]

The paper is aimed at the parametric dynamic analysis of the two degrees of freedom (DoF) phenomenological model of aero-elastic interaction between a friction-damped flexible mounted body and a flowing fluid. A coupled system of a linear structure oscillator and the van der Pol based wake oscillator is introduced. Firstly, the complex eigenvalue problem is used for the comprehensive analysis of frequency lock-in, veering and crossing areas from the structural mode stability point of view. Further, an in-depth analysis of the fully nonlinear model based on the numerical continuation method is presented. The analysis focuses on non-synchronous vibration in the resonance areas. Attention is paid to the investigation of transition mechanisms to frequency lock-in and frequency veering in the structural response. In experimental studies, the amplitude and frequency jumps are observed. Here, we show that the origin of these jump phenomena results from the mutual coexistence of two stable solutions, which form a hysteresis region, which can be found in experimentally gained data. Moreover, the influence of structure friction-damping on nonlinear response is evaluated. The proposed phenomenological model is validated concerning two different experimental-based investigations. • Phenomenological model for fluid–structure interaction with dry-friction damper. • In-depth linear and nonlinear analysis of frequency lock-in phenomenon with respect to cross-coupling parameters. • Dry-friction damper qualitatively changes subharmonic response. • Numerical continuation of periodic solutions reveals the mechanism of frequency lock-in. [ABSTRACT FROM AUTHOR]

Researchers from the University of North Carolina have developed a comprehensive mathematical model of cardiac fluid-structure interaction (FSI) in the human heart. The model incorporates biomechanically detailed descriptions of all major cardiac structures and provides anatomically and physiologically detailed representations of all four cardiac valves. It generates physiologic dynamics and can be used to predict the impacts of medical interventions, as well as for mechanistic studies of cardiac pathophysiology and dysfunction. This research has important implications for understanding and treating conditions such as congenital defects, cardiomyopathies, and heart failure. [Extracted from the article]

A recent study conducted by the Indian Institute of Technology (IIT) Kharagpur explores the impact of the stiffness of blood vessel walls and deposited plaques on coronary artery diseases. Coronary artery disease (CAD) occurs when the coronary arteries, which supply blood to the heart muscle, become narrowed or blocked due to atherosclerosis, a condition in which plaque builds up inside the arteries. The researchers developed a fluid-structure interaction model to assess the hemodynamic parameters and biomechanical environment associated with arterial disease progression. The findings of this study provide insights into cardiovascular risk assessment and could potentially improve prediction, prevention, and treatment of atherosclerosis-related conditions. [Extracted from the article]

A researcher at the Waikato Institute of Technology in New Zealand has published a report on medical diagnostics and therapy, specifically focusing on the early diagnosis of cardiovascular diseases (CVDs) such as arterial stenosis. The study compares different mathematical models used in computational studies of stenosis, specifically the laminar and k-omega shear stress transport (SST) models. The research concludes that the k-omega SST model outperforms the laminar model for short arterial segments and under the Newtonian assumption with a no-slip boundary wall and turbulent flow. This study aims to improve the accuracy of early diagnostic tools for CVDs. [Extracted from the article]

A recent study conducted by researchers at Northwestern Polytechnical University in Shaanxi, China, has developed a new method for simulating fluid-structure interaction problems in cardiac mechanics. The researchers propose an unconditionally stable scheme for the immersed boundary finite element method, which allows for larger time steps compared to conventional methods. The study validates the effectiveness and accuracy of the approach through various benchmarks and simulations. This research opens the door for further advancements in efficient solvers for the immersed boundary finite element method. [Extracted from the article]

Researchers from the Indian Institute of Technology (IIT) Kharagpur conducted a study comparing the flow of blood through bi-leaflet mechanical heart valves using both Newtonian and non-Newtonian fluid models. The study found that the assumption of blood as a Newtonian fluid, commonly used in large arteries, may not be appropriate for predicting leaflet kinematics and blood damage index in mechanical heart valves. The researchers used a sharp interface immersed boundary method with fluid-structure interaction to simulate the movement of valves and pulsatile blood flow. The findings suggest that non-Newtonian effects of blood should be considered in the design and prediction of mechanical heart valves. [Extracted from the article]

A study conducted by researchers at K.N. Toosi University of Technology in Tehran, Iran compared the mechanical properties of three commonly used grafts in coronary bypass surgeries: human saphenous veins, mammary arteries, and radial arteries. Stress-relaxation tests were performed on samples from these vessels, and their mechanical properties were analyzed. The study found that the saphenous vein had the highest elastic coefficient and non-linearity coefficient among the grafts, while the mammary artery exhibited greater viscoelasticity. The research concluded that these findings could contribute to the development of more effective treatment approaches for heart diseases. [Extracted from the article]

A recent study conducted by researchers at Cornell University in Ithaca, New York, investigated the effect of turbulence on hemolysis, the breakdown of red blood cells. The study found that existing hemolysis algorithms, which are designed for laminar flows with a constant rate of shear, may not be applicable to turbulent flows where shear rates vary significantly along cell trajectories. The researchers performed simulations of isolated red blood cells in both turbulent and laminar flows and observed that cells experienced larger deformations in turbulence due to extreme events that create bursts of high shear conditions. The study also found a strong correlation between shear rate and deformation metrics in turbulence. This research was supported by the NIH National Heart Lung & Blood Institute. [Extracted from the article]

This article discusses the contributions of pulmonary arterial remodeling to right ventricular afterload in pulmonary hypertension. Pulmonary hypertension is characterized by increased hemodynamic pressure in the main pulmonary artery, which leads to right ventricular remodeling and potentially right ventricular failure. The study used a subject-specific one-dimensional fluid-structure interaction model to investigate the alteration of pulmonary hemodynamics in pulmonary hypertension and quantify the contributions of vascular stiffening and increased resistance to increased main pulmonary artery pressure. The results showed that increased distal resistance has the greatest effect on the increase in maximum main pulmonary artery pressure, while increased stiffness caused significant elevations in characteristic impedance. This study provides valuable insights into the complex interplay between pulmonary arterial remodeling events that contribute to the adverse effects on right ventricular dysfunction. [Extracted from the article]

This paper presents a 3D boundary element time–harmonic model for the analysis of the dynamic behavior, under low-level vibrations, of the Soria arch dam (Gran Canaria, Spain). The model takes into account dynamic Soil–Structure Interaction (DSSI), Fluid–Structure Interaction (FSI) and the actual geometry of dam wall and reservoir. The rock and the dam wall are considered as viscoelastic regions, and the water in the reservoir is modeled as an inviscid fluid. The influence of DSSI, FSI, height of the water in the reservoir, accuracy of the geometric modeling of the canyon, and type of transmitting boundary conditions at the truncated end of the reservoir, are evaluated. DSSI and FSI have a significant influence on the dynamic response of the dam, and the accurate representation of the geometry of the canyon is relevant for the correct estimation of the modal shapes. Ambient vibrations tests were also performed, from which the first and third modes could be clearly identified. The comparison between the experimental and numerical natural frequencies and mode shapes suggests that the proposed complete numerical model is able to capture the dynamic response and can be used for the structural health monitoring of the wall of this dam. [ABSTRACT FROM AUTHOR]

A recent study conducted at the Motilal Nehru National Institute of Technology Allahabad in Uttar Pradesh, India, explored the creeping peristaltic propulsion of viscid fluid in an annular gap between sinusoidally deforming permeable and impermeable curved tubes. The researchers investigated the effects of an externally imposed electric and magnetic field on the flow through the gap. The study provides insights into the underlying physics of the flow phenomena and has important implications for engineering applications in fields such as mechanical and biomedical engineering. The research fills a gap in the existing literature on the topic. [Extracted from the article]

A new study from the University of Chile explores the effects of size and wall thickness on the rupture risk of cerebral aneurysms. The researchers used fluid-structure interaction simulations to assess six patient-specific geometries, focusing on size and wall thickness variations. The study found that while aneurysm size has a significant impact on rupture risk, wall thickness should also be considered, as thinning walls can lead to structural failure. The research highlights the importance of understanding these factors in order to prevent aneurysm rupture. [Extracted from the article]

The stability of fluid–structure interaction (FSI) problems using immersed boundary (IB) method is an active area of research. In this regime, strong coupling is generally used to ensure stability and robustness. Strong coupling, however, is computationally expensive owing to its iterative nature. In the present work, we showcase the application of loose coupling algorithm for FSI problems using the sharp interface IB method specifically for low to moderate mass ratios (defined as the ratio of the mass of the structure to the mass of the fluid at the same volume). We demonstrate several test cases: vortex-induced vibration (VIV) of a cylinder, the effect of hinged leaflets attached to the exit of a piston in a channel, sedimentation of a circular disk, and bi-leaflet mechanical heart valves (BMHV) made of lightweight materials in physiological flow. We found our loose coupling method to be stable in all the test cases and obtained a linear relationship between the grid resolution employed and the lowest mass ratio for stable computations in the case of VIV of cylinder. Thus, a significant finding of our work is that with a reduction in grid spacing, one can achieve stable FSI simulation involving lower mass ratios using loosly-coupled schemes. We have deployed the present technique to investigate the dynamics of very low-density cylinders and hinged leaflets due to the fluid forces on them. The current method is extended to handle flexible bodies, such as vortex-induced vibrations of an elastic plate attached to a rigid cylinder and stable simulations are obtained when the Young's modulus of the elastic plate is varied. [Display omitted] • Development of a loose coupling based Fluid Structure Interaction scheme. • Mass ratios as low as 0.009 is found to be stable for VIV of a cylinder. • Stable simulation of moving mechanical heart valves using loose coupling is obtained. • The FSI scheme is augmented for flexible bodies. [ABSTRACT FROM AUTHOR]

We introduce a novel positivity-preserving numerical stabilisation approach for high-order discontinuous spectral element approximations of compressible multi-species flows. The underlying stabilisation method is the adaptive entropy filtering approach (Dzanic and Witherden, J. Comput. Phys. , 468, 2022), which is extended to the conservative formulation of the multi-species flow equations. We show that the straightforward enforcement of entropy constraints in the filter yields poor results around species interfaces and propose an adaptive switch for the entropy bounds based on the convergence properties of the pressure field which drastically improves its performance for multi-species flows. The proposed approach is shown in a variety of numerical experiments applied to the multi-species Euler and Navier–Stokes equations computed on unstructured grids, ranging from shock-fluid interaction problems to three-dimensional viscous flow instabilities. We demonstrate that the approach can retain the high-order accuracy of the underlying numerical scheme even at smooth extrema, ensure the positivity of the species density and pressure in the vicinity of shocks and contact discontinuities, and accurately predict small-scale flow features with minimal numerical dissipation. • Novel positivity-preserving scheme for compressible multi-species flows. • High-order discontinuous spectral element method with adaptive nonlinear filtering. • Proposed entropy switch to improve resolution of species interfaces. • Applied to inviscid and viscous multi-species flows with shock waves and turbulence. [ABSTRACT FROM AUTHOR]

A study conducted by researchers at Peking University in Beijing, China, focuses on patient-specific simulations of cardiovascular fluid-structure interactions. The study addresses the challenges of modeling these interactions, which involve complex interfaces, morphing flow domains, and non-trivial structural deformation. The researchers developed a framework that combines an incompressible smoothed particle hydrodynamics (SPH) method with a total Lagrangian SPH (TLSPH) method to accurately simulate the dynamics of blood vessels and the hemodynamics. The framework was validated through simulations of pulse wave propagation in straight vessels and the FSI processes in blood vessels with stenosis and patient-specific aorta. The results demonstrate the effectiveness and efficiency of the framework for patient-specific blood vessel simulations. The study was funded by the National Natural Science Foundation of China, Beijing Natural Science Foundation, and Sino-German Mobility Programme. [Extracted from the article]

Flows of an incompressible Navier–Stokes fluid are frequently assumed to take place in domains whose boundaries are rigid and that the fluid adheres to them, i.e. there is the "no-slip" on the interface between the rigid solid and the flowing fluid. However, in many interesting problems the walls respond as (visco)-elastic structures and different slipping conditions on the fluid–structure interface seem to be more appropriate. Our main objective is to develop a reliable numerical approach capable of efficiently solving such fluid–structure interaction problems with Navier's slip interface conditions in three dimensions. We focus on axi-symmetric flow problems; their two-dimensional character allows us to perform systematic testing of the performance of the solver and to study the effects of the (visco)-elasticity of the wall and the value of Navier's slip-parameter on the properties of the flow including the vorticity, dissipation, pressure drop and wall shear stress. All tests concern steady and time-periodic flows in pipe-like domains with sinuses. It is startling that, in this geometric setting, the effects of (visco)-elasticity of the structure on the flow are minor in comparison to the setting when the walls are rigid. [ABSTRACT FROM AUTHOR]

• Influences of flow on hydrodynamic behavior of undulated beam are studied. • Mechanism of hydrodynamic behavior change in flow environment is revealed. • Performance of beam in flow environment is discussed, as well as a routing problem. • Loosely coupled partitioned algorithm is extended for self-propelled beam in flow environment. Undulated biomimetic propulsion has gained an extensive attention with upsurge of bionic applications. However, its performance in different flow environments is rarely discussed. In this paper, hydrodynamic behavior of an undulated beam in flow environments is studied, as well as its routing problem. The previously proposed loosely coupled partitioned algorithm is adopted. Motion of an undulated beam in still water is simulated to validate this algorithm. And then, hydrodynamic behavior of beam in flow environments with different directions and velocities is studied. It is found that velocity of beam is linearly affected by longitudinal flow and symmetric vortex structure still keeps. While transverse flow leads to the unequal amplitudes of velocity valley and crest, and symmetric vortex structure is lost. The influence of oblique flow could be regard as the combination of longitudinal and transverse flow components. Flow details are analyzed to reveal the mechanism of those hydrodynamic changes. Transverse flow component plays an important role. It significantly changes the pressure difference around beam and promotes the mixture of vortex. Besides, performance of beam in different flows and routing problem indicate that the straight path between the beginning and ending points is not always the best choice. [ABSTRACT FROM AUTHOR]

The present study examines flow through Bi-Leaflet Mechanical Heart Valves (BMHV) at physiological conditions considering both Newtonian and non-Newtonian fluid models for blood rheology. It is well known that the non-Newtonian effects of blood are pronounced in small diameter arteries. Most of the earlier works on Mechanical Heart Valves (MHV) have considered blood as a Newtonian fluid as the flow involves large-diameter artery such as the aorta. In this work, we have reported the predicted parameters, such as leaflet kinematics, vortex structures, wall shear stress, and blood damage index for both blood models. It is found that the leaflet attributes smaller asynchronous motion in the case of non-Newtonian Carreau fluid model with slightly reduced angular velocity compared to the Newtonian assumption. Predictions on the blood damage index suggest a 21% higher damage while using non-Newtonian model than Newtonian model, which may be attributed to higher levels of mechanical stress within the fluid. However, vortex structures, time-averaged wall shear stress (TAWSS), and oscillatory shear index (OSI) are found to be similar in predictions using both the fluid models. We have used an in-house sharp interface immersed boundary method with fluid–structure interaction to simulate the coupled action of moving valves and pulsatile blood flow. Our findings suggest that the general consensus of using Newtonian model in large arteries may not be appropriate for prediction of leaflet kinematics and blood damage index in Mechanical heart valves. • Newtonian and non-Newtonian blood flow through BMHV is studied. • Carreau model suggests a reduced asynchronous leaflet motion and angular velocity. • Qualitative features indicate more stable flow structures for Carreau model. • Elevated blood damage by 21% is predicted by Carreau model. • Hemodynamic parameters- TAWSS, OSI, and RRT are similar in range for both the models. [ABSTRACT FROM AUTHOR]

A study conducted at the University of Notre Dame in Indiana explores the development and sizing of transcatheter heart valves (THVs) for the treatment of valve diseases. The research proposes a parametric modeling approach that allows for flexible valvular development and sizing, which can generate both existing and novel valve designs. The study uses an immersogeometric fluid-structure interaction (IMGA FSI) framework to analyze the impact of geometric changes on THV performance. The research concludes that the proposed modeling framework enhances THV performance and efficacy, offering potential advancements in the treatment of valve diseases. [Extracted from the article]

Experimental tests accessing both fluid and structure behaviors are mandatory for a consistent and comprehensive assessment of fluid–structure interaction (FSI) numerical simulations. In this paper, recently published results of an experimental configuration of two in-line cantilever cylinders subjected to water cross-flow were considered: instantaneous fluid velocities measurements are available on several positions inside the test section, together with the cylinder vibrations. FSI simulations were performed by coupling Ansys Fluent (for the fluid domain) with Ansys Mechanical (for the solid domain). URANS simulations and Scale-Adaptive Simulations (SAS) were employed as CFD simulation approach. The structure displacements were taken into account through an Arbitrary Lagrangian–Eulerian approach. The fluid–structure coupling was 2-way explicit. Simulations were performed for two different water mass flow rates. For the highest one, vortex-induced resonance was observed experimentally. The numerical results show consistent agreement in terms of shedding frequency and velocity spectra behind the cylinders. The calculated vibration response is overall consistent, despite some underestimations, for the cylinders not featuring vortex-induced resonance; nevertheless, the experimentally observed vortex-induced resonance could not be reproduced by the numerical simulations. • Existing experimental results on FIV employed to assess CFD FSI simulations. • URANS and hybrid URANS/LES CFD approaches were tested: the latter proved superior. • Good agreement in terms of flow velocity spectra and mean profiles. • Coupled fluid-structure simulations were run to calculate the cylinder vibration. • Better agreement with exp. measurements for the second cylinder than for the first one. • A resonance was observed experimentally for the first cylinder at a given flow rate. • The resonance could not be predicted numerically. [ABSTRACT FROM AUTHOR]

Our paper proposes an innovative approach for modeling Fluid–Structure Interaction (FSI). Our method combines both traditional monolithic and partitioned approaches, creating a hybrid solution that facilitates FSI. At each time iteration, the solid mesh is immersed within a fluid–solid mesh, all while maintaining its independent Lagrangian hyperelastic solver. The Eulerian mesh encompasses both the fluid and solid components and accommodates various physical phenomena. We enhance the interaction between solid and fluid through anisotropic mesh adaptation and the Level-Set methods. This enables a more accurate representation of their interaction. Together, these components constitute the Adaptive Immersed Mesh Method (AIMM). For both solvers, we utilize the Variational Multi-Scale (VMS) method, mitigating potential spurious oscillations common with piecewise linear tetrahedral elements. The framework operates in 3D with parallel computing capabilities. Our method's accuracy, robustness, and capabilities are assessed through a series of 2D numerical problems. Furthermore, we present various three-dimensional test cases and compare their results to experimental data. • A novel hybrid coupling method for FSI that takes the advantages of the partitioned approach, and retaining the advantages of the monolithic approach. • Ability to handle 2D/3D sharp membrane like geometries and interfaces through tetrahedral anisotropic unstructured finite elements.. • The level set method is used in the immersion of the solid mesh onto the fluid–solid mesh for interface tracking. • Variational Multi-Scale (VMS) stabilization for piece-wise linear finite elements to damp out spurious pressure oscillations and highly advective flows. • Moving Mesh Method (MMM) that considers the solid dynamics and helps track the FSI interface on the solid mesh. [ABSTRACT FROM AUTHOR]

We present a finite element framework for the numerical prediction of cavitating turbulent flows interacting with flexible structures. The vapor–fluid phases are captured through a homogeneous mixture model, with a scalar transport equation governing the spatio-temporal evolution of cavitation dynamics. High-density gradients in the two-phase cavitating flow motivate the use of a positivity-preserving Petrov–Galerkin stabilization method in the variational framework. A mass transfer source term introduces local compressibility effects arising as a consequence of phase change. The turbulent fluid flow is modeled through a dynamic subgrid-scale method for large eddy simulations. The flexible structure is represented by a set of eigenmodes, obtained through a modal decomposition of the linear elasticity equations. While a partitioned iterative approach is adopted to couple the structural dynamics and cavitating fluid flow, the deforming flow domain is described by an arbitrary Lagrangian–Eulerian frame of reference. We establish the fidelity of the proposed framework by comparing it against experimental and numerical studies for both rigid and flexible hydrofoils in cavitating flows. Under unstable partial cavitating conditions, we identify specific vortical structures leading to cloud cavity collapse. We further explore features of cavitating flow past a rigid body such as re-entrant jet and turbulence-cavity interactions during cloud cavity collapse. Based on the validation study conducted over a flexible NACA66 rectangular hydrofoil, we elucidate the role of cavity and vortex shedding in governing the structural dynamics. Subsequently, we identify a broad spectrum frequency band whose central peak does not correlate to the frequency content of the cavitation dynamics or the natural frequencies of the structure, indicating the induction of unsteady flow patterns around the hydrofoil. Finally, we discuss the coupled fluid–structure dynamics during a cavitation cycle and the underlying mechanism associated with the promotion and mitigation of cavitation. • Unified variational framework for cavitating flow and fluid–structure interaction. • Robust and accurate cavitation modeling via homogeneous mixture theory. • Partitioned iterative coupling for turbulent cavitating flow-structure interaction. • Validation of turbulent cavitating flow for rigid and flexible hydrofoils. • Role of bend-twist coupling in altering cavity-vortex shedding dynamics. [ABSTRACT FROM AUTHOR]

The aim of this article is to analyse the nonlinear biomechanics of diseased carotid arteries as a potential tool for predicting the onset of cerebral strokes. A two-way coupled three-dimensional (3D) hyperelastic fluid-structure interaction (FSI) analysis of a diseased carotid artery with abnormal luminal projections at the carotid bulb known as carotid web (CaW) is conducted on the geometry of a patient artery, built upon employing CT angiography images. The blood-flow model incorporates non-Newtonian pulsatile turbulent fluid, and the artery wall is considered hyperelastic subject to blood-induced motion. The hemodynamics of artery induced by transient boundary conditions is determined, specifically focusing on shifts in crucial hemodynamic parameters such as wall shear stress (WSS) and alterations in the blood velocity pattern. Structural assessment of the artery wall involves quantifying the von Mises (VM) stress and deformation field. The analysis demonstrates that different CaW models result in different flow patterns for a selection of time steps in a cardiac cycle. The findings reveal that the presence of the web, as the most common disease among younger adults, can significantly influence the hemodynamic parameters and potentially accelerate the formation of thrombus and atherosclerosis. Hemodynamic analysis can potentially predict specific sites prone to plaque formation and rupture within the carotid artery. [ABSTRACT FROM AUTHOR]

In this paper, an Explicit Galerkin Finite Volume Method (E-GFVM) is employed to estimate damage paths in concrete structures through the definition of nonlinear behavior of concrete. Furthermore, to verify the accuracy and efficiency of the present method, the E-GFVM outcomes are compared with the Explicit Finite Element Method (E-FEM) which is a well-known numerical method for investigating numerous solid mechanics problems. Due to the essence of explicit methods, the method in question uses a few matrix operations in nonlinear analysis, so it diminishes computation workloads for time-dependent cases with small time-step. The reason for using E-GFVM was its simplicity and high accuracy in estimating stresses and displacements for the analysis of Computational Solid Mechanics (CSM) problems. Furthermore, one important feature of FVM is its local conservation properties which guarantee the global conservation of variables that provides more stability, particularly in dealing with complex problems. To model the nonlinear behavior of concrete, the two equivalent uniaxial stress–strain relations, taking into consideration the softening and hardening behavior in both compression and tension, are implemented in the proposed numerical method. In other words, the bi-axial concrete behavior is defined by applying the idea of current strength in principal stress space. Therefore, this study aims to introduce a new numerical method that in addition to reducing time consumption, can maintain the accuracy of the results. For reaching this purpose, first, the nonlinear behavior of concrete is modeled and two different specimens are placed under pure pressure and tension loads. The results calculated by the E-GFVM are compared with other literature. After verification of the nonlinear behavior of concrete using E-GFVM, the ability of the proposed method for analysis of a real-world case under time-dependent conditions, namely Koyna concrete gravity dam which experienced a destructive earthquake in 1967, is tested, considering the impacts of dam–reservoir interaction. Then, this problem with the same conditions is modeled and analyzed using the E-FEM. The results show that, in spite of good harmony between two utilized methods for estimating the damage on the body of Koyna dam, the CPU time of the E-GFVM became about 3 times less than the E-FEM. [ABSTRACT FROM AUTHOR]

• A fully lagrangian meshfree implicit structure model is developed with three novel schemes (HT-PC-HD). • HT; High-order implicit time integration for update of particles' velocities and positions. • PC; predictor-corrector method for estimation of rotation matrix. • HD; High-order discretization operator models for deformation gradient and acceleration by elastic force. • The implicit structure model and integrated FSI solver are shown to have good accuracy and stability. In this paper, a novel SPH (Smoothed Particle Hydrodynamics)-based implicit structure model as well as its refined coupled fully-Lagrangian meshfree FSI (Fluid-Structure Interaction) solver are presented. The implicit structure model is founded through consideration of conservation law of linear momentum. The implicit time integration is achieved along with the assumption of linear elastic material. For development of refined implicit structure model, three novel schemes are considered; (1) High-order implicit Time integration (HT) scheme is considered for enhanced implicit update of particles' velocities and positions; (2) Predictor-Corrector (PC) method is incorporated for improved estimation of rotation matrix; (3) High-order Discretization (HD) operator is employed for consistent calculation of deformation gradient and acceleration by elastic force. The proposed SPH-based implicit structure model is coupled with a refined ISPH fluid model so as to develop an enhanced fully-Lagrangian meshfree FSI solver, where consistent time coupling between incompressible fluid flow and stiff structures can be achieved by using the same time step sizes in both phases. The proposed implicit structure model as well as its corresponding FSI solver are verified in terms of robustness and accuracy by reproducing a set of well-known benchmark tests. [Display omitted] [ABSTRACT FROM AUTHOR]