Fluid-structure Interaction Algorithm Research Articles

Compressible FSI of elastic spikes for drag reduction under hypersonic flow

In this study, a new fluid structure interaction (FSI) algorithm is developed for the aerodynamic-elasticity problem, aiming to address the coupling problem between compressible fluids and deformable solid structures. To verify the feasibility of the proposed model, a two-dimensional cantilever panel case under shock waves was conducted. Our numerical results present good consistency with the data from literatures. Furthermore, the validated FSI algorithm is applied on an elastic spike under compressible hypersonic flow. The complicated interaction between the fluid and solid structure under various spike geometry sizes and materials were revealed in respect of the spike deformation, pressure, temperature, and flow fields distribution. The main findings show that the spike deformation largely affects pressure and temperature on the blunt, the aerodynamic drag and lift force, indicating the necessity of FSI. For the spike diameters and lengths, it is found that larger spike diameters and shorter spikes benefits for deformation reduction, thereby minimizing fluctuations in aerodynamic drag force. For spike materials, spikes with larger elastic moduli and lower densities are preferred for the drag reduction. Thus, the proposed FSI model can accurately predict flow fields around and deformations for elastic spikes and offer guidance for drag reduction design in aerospace engineering.

Dynamic behaviors of concrete gravity dam against combined blast wave and bubble pulsation of underwater explosion

Underwater explosion process mainly includes the preceding blast wave and the succeeding bubble pulsation, while the effect of bubble pulsation on hydraulic structures is always neglected. This paper aims to numerically study the dynamic behaviors of prototype concrete gravity dam against underwater explosion, considering the combined effects of blast wave and bubble pulsation. Firstly, a finite element analysis (FEA) approach for predicting the underwater explosion loadings, as well as the damage evolution and dynamic responses of dam against underwater explosions was proposed, in which the hydrostatic pressure of reservoir and the dead load of dam were considered. Based on Cole's formula and the existing underwater explosion tests, the reliability of FEA approach, including the mesh sizes, material models and the corresponding parameters, as well as the mapping, Fluid-Structure Interaction and contact algorithms, was comprehensively validated. Secondly, to realize the simulation of the prototype gravity dam impeded by the validated small Lagrange mesh size, a mesh transition strategy was proposed based on the equivalence of dam damage modes and total eroded element mass. Finally, the dynamic behaviors of a typical 120 m-height concrete gravity dam against underwater explosion, i.e., 1 t of TNT equivalence detonated at a depth of 35 m and standoff distances of 4–16 m, were examined. The dimensionless distance λR, i.e., the ratio of the standoff distance to the maximum bubble radius, was introduced to quantitatively evaluate the underwater explosion loadings and dynamic behaviors of the dam. It indicates that, the blast wave firstly leads to the local compressive damage on the upstream surface, as well as the tensile damage on the downstream folded slope and dam heel. The succeeding free vibration and bubble pulsation will further aggravate the damage degree, resulting in the cracking of dam neck and heel. Especially for the scenarios when λR ≤ 1.22, the overall sliding of dam is highly prone to occur.

Coupling of the immersed boundary and Fourier pseudo-spectral methods applied to solve fluid–structure interaction problems

The current manuscript addresses fluid–structure interaction (FSI) problems to the analysis of vortex-induced vibration (VIV), employing the methodology designated as IMERSPEC2D. The approach seamlessly integrates the Fourier pseudo-spectral method (FPSM) and the immersed boundary method (IBM) to solve the Navier–Stokes (NS) and continuity equations. Simultaneously, the effects of cylindrical structure, involving 1 and 2 degrees of freedom (d.o.f.) are simulated, by incorporating structural motion equations into NS via the IBM source term and implementing a two-way FSI algorithm. In the paper are presented the comparison of low and high-order temporal integration methods applied to solve the dynamic behavior of the structure and the dimensionless of the cylinder’s structural motion equations, resulting in an increase in computational time step from 1E(-9\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-9$$\\end{document}) to 1E(-3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$-3$$\\end{document}). Validation results to refined mesh simulations include the accurate representation of the lock-in phenomenon to simulations of 1 d.o.f. obtaining the range between reduced velocity 5.456 and 5.568 and the maximal amplitude is 0.352. Notably, the eight-shape pattern of the 2 d.o.f. cylinder displacement is obtained and the formation of C2S wake patterns is achieved, as presented by other authors. In conclusion, the dimensionless approach reduces computational time, while the high-order both of IMERSPEC methodology and time advancement integration to FSI improve the results of the cylinder’s motion and alters distinct vortex shedding patterns in fluid dynamics.

Abstract 17617: Toward Improving Diagnosis and Interventional Predictability in Aortic Valve Stenosis Using Computational Modeling

Introduction: Watchful waiting for symptoms or critical hemodynamics to intervene on aortic stenosis (AS) may delay too long. While stress tests can detect symptoms in allegedly asymptomatic AS patients, image-based computations based on advanced modeling techniques can provide critical biomechanical insights. Hypothesis: Advanced computational modeling techniques utilizing patient data backed by high-performance computing can inform a personalized understanding of disease progression, diagnosis, and anticipated post-op hemodynamics to predict interventional efficacy. Methods: A validated in-house Fluid-structure Interaction (FSI) algorithm that allows easy translation of patient-specific anatomies was utilized to perform "virtual stress test" on a moderate AS with increasing LV contraction to predict systolic ejection dynamics under stress. TAVR was virtually implanted and post-op aortic hemodynamics were quantitatively compared with pre-op (diseased) data. Results: Predictions demonstrated that that aortic flow turbulence in moderate AS (Re = 11,700) during exercise (115 bpm) can be similar to severe AS (Re=10,000) at rest (70 bpm) resulting in a greater dissipation losses rising linearly with heart rates. As LV contraction rose, each valve cusp underwent a distinct non-linear rise (>100%) in mechanical stresses that can accelerate calcification. Interestingly, our evaluation revealed that the heterogenous ΔP vs. Q relationship in AS observed clinically can be attributed to a non-linear rise in aortic valve area occurring during mid-systole. Aortic hemodynamics improved post-TAVR by reducing dissipation losses by ~11 fold and restoring near-normal peak-systolic velocity (1.7 m/s) in the ascending aorta. Conclusions: High-performance based multi-physics algorithms incorporating patient data might offer comprehensive biomechanical insights into diagnosis and interventional suitability for aortic valve stenosis.

Investigation of Structural Strength and Fatigue Life of Rotor System of a Vertical Axial-Flow Pump under Full Operating Conditions

Axial-flow pumps consider both the conventional pump mode and the pump as turbine (PAT) mode operation and put forward higher requirements for long-term operation stability and structural strength; therefore, it is of great engineering significance to evaluate the structural strength and fatigue life of the rotor under full operating conditions. In this study, based on computational fluid dynamics and the one-way fluid-structure interaction algorithm, the structural strength and fatigue life of the rotor system of a large vertical axial-flow pump under full operating conditions were evaluated and studied. The results show that blade deformation and equivalent stress are generally higher in the PAT mode than in the pump mode. The maximum deformation in both modes occurs at the tip of the blade, while the area of stress concentration is at the root of the blade. Both the deformation and the equivalent stress increase with increasing flow rate. The minimum safety factor occurs at the blade root in both modes, and the safety factor in the PAT mode is relatively smaller than that in pump mode. Therefore, when designing and manufacturing axial flow pumps for turbine duties, priority should be given to material strength at the blade root during PAT mode operation to ensure safe and stable operation. The aim of this study is to provide technical references and theoretical foundations for evaluating the service cycle of axial-flow pumps and the influence on pump life under different operation modes.

LS Dyna ile Serbest Hava Ortamındaki Patlama Yükünün Sayısal Simülasyonu için SPH, ALE, Birleştirilmiş ALE-LBE ve CONWEP Yöntemlerinin İncelenmesi

Different simulation methods can be used to model the response of structures to the effects of blast loading. While some simulation methods are based on empirical blast loading principles, other methods use a fluid structure interaction algorithm to predict post-explosion shock waves and their physical effects. In this study, CONWEP, SPH, ALE, and coupled MM-ALE with LBE numerical methods were compared against each other according to results from an experimental study. Each method was compared with the test results in terms of solution time, convergence, and the use for different explosive types and environments. According to this comparison, it was concluded that empirical methods can be used for more limited environmental conditions and blast types, ALE numerical methods can give very sensitive results even in different solution sets but the solution time is long. Meanwhile in SPH method, the interaction of the air and blast shock cannot be fully modelled. According to the results of the study, the hybrid method is consistent with the test results in terms of peak pressure with a deviation of 7.44% at P1 and 2.29% at P2 under spherical free air blast loading conditions. However, since the effects of reflected pressure cannot be modelled exactly in the hybrid method, the ALE method should be preferred in cases with more complex geometries.

Study on Radial Distribution of Fragments Velocity of D-shaped Fragmentation Warhead

For the asymmetric D-shaped fragmentation warhead with high charging coefficient and space efficiency, we simulate the driving process of fragments under typical eccentric initiation by using the fluid-structure interaction algorithm, and obtained the change rule of the fragment velocity radial distribution with the central angel, the thickness and material of the upper end cap. The results of numerical simulation show that the fragment velocity of D-shaped warhead increases gradually from the reverse to the forward direction, the velocity of fragment in forward direction increases by about 10% under single-point eccentric initiation compared with the cylindrical casing under center initiation, and the fragment velocity under double-point eccentric initiations is higher than single-point eccentric initiation; The initial velocity of the fragment has a positive correlation with the thickness and density parameters of the upper end cap; the mass of the warhead and the total kinetic energy of the fragments in the forward area increase with the increase of the central angle, but their ratio increases first and then decreases with the increase of the central angle. The results can be applied to structural optimization design and power evaluation of the warhead.

Hydrodynamic performance optimization of marine propellers based on fluid-structure coupling

Fiber-reinforced composites offer the benefits of high strength, high stiffness, lightweight, superior damping performance, and great design capability when compared to metal. The rigidity characteristics of the composite laminate in different directions may be adjusted to meet the requirements of the application by using appropriate materials and arranging the lay-up sequence. As a result, the purpose of this work is to explore the influence of lay-up type on propeller performance in terms of both hydrodynamic and structural performance. A transient fluid-structure interaction (FSI) algorithm based on the finite element method (FEM) combined with the computational fluid dynamics (CFD) technique is developed and used for the analysis of composite propellers. The hydrodynamic performance of the propeller is compared to that of a metallic material. Propeller propulsion efficiency, structural deformation, equivalent stress, and damage performance of different lay-up options under three different operating situations are compared. In addition, it is presented a parametric optimization approach to get the most appropriate lay-up program for composite blades with the best hydrodynamic properties and structural performance.

Seismic responses of liquid storage tanks subjected to vertical excitation of near-fault earthquakes

This study aims to evaluate the effect of vertical seismic component on dynamic responses of liquid storage tanks, with a special focus on near-fault earthquakes. A shaking table test was performed on a 1:25 scaled steel tank, which was loaded by both far- and near-fault ground motions with horizontal unidirectional, vertical unidirectional, and combined horizontal and vertical bi-directional excitations. Seismic responses, including sloshing height and hydrodynamic pressure were recorded and compared. Subsequently, a refined finite element (FE) model of the scaled tank model was established by utilizing the structured Arbitrary-Lagrange-Eulerian (S-ALE) solver and Fluid-Structure Interaction (FSI) algorithm, which was verified by comparison with the test results. Afterward, the modeling methodology was further applied to a prototype large-scale liquefied natural gas (LNG) inner tank for seismic analysis. In addition, seismic responses of the LNG inner tank were compared with the recommendations given in seismic design codes for cylindrical tanks. The experimental and numerical findings showed that both the convective and impulsive motions of liquid was amplified by vertical excitations, especially under near-fault earthquakes. The peak sloshing heights under near- and far-fault earthquakes were increased by 14–142% and 8–56% due to the existence of vertical action, respectively. The LNG inner tank was more vulnerable to inelastic buckling due to the presence of vertical seismic component. Moreover, the effect of vertical excitations of near-fault earthquakes on hydrodynamic pressure and tank stresses was underestimated by the current seismic design codes.

Overset meshing in combination with novel blended weak-strong fluid-structure interactions for simulations of a translating valve in series with a second valve

Mechanical circulatory support (MCS) devices can bridge the gap to transplant whilst awaiting a viable donor heart. The Realheart Total Artificial Heart is a novel positive-displacement MCS that generates pulsatile flow via bileaflet mechanical valves. This study developed a combined computational fluid dynamics and fluid-structure interaction (FSI) methodology for simulating positive displacement bileaflet valves. Overset meshing discretised the fluid domain, and a blended weak-strong coupling FSI algorithm was combined with variable time-stepping. Four operating conditions of relevant stroke lengths and rates were assessed. The results demonstrated this modelling strategy is stable and efficient for modelling positive-displacement artificial hearts.

Study of flow field and vibration characteristics of supersonic centrifugal impellers based on fluid-structure interaction

PurposeThere 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/approachFirst, 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.FindingsThe 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/valueThe 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.

High fidelity coupling methods for blast response of thin shell structures

Computational simulation of structures subjected to blast loads requires integration of computational shock physics and structural response with finite deformations. The authors’ particular application of interest is blast loads on thin shell structures, which often deform concurrently with the shock or pressure wave evolution over the structure. This necessitates two-way coupled algorithms. We combine state-of-the-art shock physics, structural modeling with shell finite elements, and an immersed boundary method that accommodates arbitrarily thin structures. Building on successful techniques in the literature, we focus on accuracy and convergence rates of novel extensions to time step coupling approaches and immersed boundary treatments. The new techniques are developed to easily integrate with typical, industry-standard production analysis codes. The final recommended technique combines centered-difference structural time integration, predictor–corrector fluid time integration, level set surface tracking, and the Half Riemann Immersed Boundary method. Examples are given that show robust and accurate modeling of shock and pressure wave problems, and verification problems highlight good convergence properties for both fluid and fluid–structure applications. • Fluid–structure interaction algorithms for blast loads on thin structures. • Combine shock-physics, shell finite elements, and immersed boundaries. • Explore convergence rates of time step coupling and immersed boundary treatments. • Coupling approach takes advantage of convergence rates of underlying solvers.

Swimming near substrates: Stingray self-propelled undulatory simulations

Fish movement investigations typically assume motion through unbound fluids. However, benthic organisms experience ground effects when moving near substrates. To identify the internal ground-effect mechanisms on self-propelled stingrays, simulations applying an in-house developed fluid-structure interaction algorithm were performed. A geometric model was developed from three-dimensional (3D) laser-scan data of a live freshwater stingray. The ratios of distances between the stingray and solid boundary to its disc width and unbounded fluid were investigated at two swimming frequencies: 2.385 and 3.384 Hz. Velocity fluctuation amplitude during one cycle near a substrate was approximately 30% less than that in unbounded fluid. The two peaks of the force coefficient in one cycle decreased and increased, respectively, with decreased power loss near the substrate; this is related to the pressure and wake distributions on the lower stingray surface at two typical instances. Pressure regions on the front and rear lower wing-crest surfaces decreased when approaching the substrate at the first typical instance, whereas that of the wing trough increased for the second typical instance. The vortex size on the lower wing surface decreased near the substrate for both instances.

Numerical analysis of the impact of an inclined plate with water at high horizontal velocity

High-speed planing craft, aircraft when ditching into the water, and ground vehicles entering water can experience violent interaction with the water surface that leads to structural failure. The largest loads typically occur over a very short time, but the magnitude of the pressure and force can be extreme and important for design considerations of safe vehicles. In this paper the water entry problem is studied numerically with one-way and two-way-coupled fluid–structure interaction algorithms. One-way simulations assume a rigid structure while solving for the fluid domain solution, whereas the two-way-coupled approach captures the added mass effects by accounting for the plate deformation in the fluid solution. The primary objectives of this study are to present and validate the numerical methodology, and provide insight into the fundamental physical processes that are important for three-dimensional high-speed aircraft ditching and marine-vessel slamming problems. The fluid solution is obtained using the finite-volume discretization of the incompressible Navier–Stokes equations and the volume-of-fluid method to capture the air–water interface. The structural response is obtained using a modal decomposition representation of the dynamic finite-element system. The fluid–structure-interaction framework is validated by comparison with previously published experimental measurements of an aluminum plate that enters the water with a large horizontal-to-vertical velocity ratio. Several test conditions are discussed that ensure that the numerical solver can capture highly localized pressure maxima, the hydrodynamic force, the behavior of the jet-root propagation, and hydroelastic coupling. Simulation results show the capability to accurately capture these complex phenomena which are important to modeling water-entry problems for the design and certification of air-, land-, and water-craft.

Numerical simulation on influence of initial pressures on gas explosion propagation characteristics in roadway

In order to investigate the influence of initial pressures on the propagation characteristics of gas explosion in roadway, the physical model of gas explosion under different initial pressures in roadway is established by the fluid-structure interaction algorithm of ANSYS/LS-DYNA. The pressure of shock wave, the rise rate of pressure and the flame propagation velocity are analyzed when the initial pressure is 0.08, 0.09, 0.10, 0.11, and 0.12 MPa, respectively. The results reveal that the maximum pressure of shock wave at the same position in the roadway increases significantly with the increase of initial pressure, which presents a quadratic function relationship. The time to reach the maximum pressure of shock wave is extended comparatively. In addition, the maximum rise rate of shock wave pressure increases with the increase of the initial pressure, which means that the explosion hazard increases. The flame propagation velocity in the roadway decreases linearly with the increase of initial pressure. When the initial pressure increases by 0.01 MPa, the flame propagation speed will decrease by 2.6%.

Progressive collapse of Murrah Federal Building: Revisited

As a typical incident of progressive collapse of RC structures caused by the terroristic vehicular bomb attack, the large-scale collapse of Murrah Federal Building (MFB) in 1995 has been attracting extensive attentions. The alternate path method and the direct simulation method are commonly adopted to evaluate the progressive collapse resistance of buildings. However, the simultaneous damage of the structural members adjacent to the removed column and the instantaneous interactions between the blast wave and the structures are neglected. This paper aims to revisit the progressive collapse of MFB through the high-fidelity numerical simulations. Firstly, the hybrid finite element model of MFB was established including both the near-range refined model and far-range simplified model. Secondly, based on the explicit dynamic finite element program LS-DYNA, the Arbitrary Lagrangian-Eulerian (ALE) method and Fluid-Structure Interaction (FSI) algorithms were adopted to simulate the ignition of explosive, propagation of air blast wave and its interactions with the building structures, which was validated based on an external explosion test on RC frame structure. Furthermore, the collapse of MFB was predicted and compared with the on-site photographs in terms of the collapse scopes of entire building and the damage of local structural members. Finally, three seismic resistant design schemes of MFB were proposed, and the corresponding progressive collapse resistance of which was further evaluated. It derives that, (i) the numerical simulation combining the hybrid modelling and ALE approaches can well reproduce the collapse process of MFB; (ii) the progressive collapse of MFB is mainly caused by the insufficiency of flexural bearing capacity of the transfer girder due to the failure of three supporting ground columns, rather than the rotation of the transfer girder; (iii) the three improved schemes can partially prevent the shear failure of the ground columns and mitigate the collapse scopes of MFB by 25%–50%, while the progressive collapse still occurs due to the shear failure of transfer girder; (iv) transfer girder is not recommended for blast-resistant buildings due to its low redundancy.

The Effects of Implantation Orientation of a Bileaflet Mechanical Heart Valve in an Anatomic Left Ventricle-Aorta Configuration.

We have performed three-dimensional high-resolution numerical simulations of a bi-leaflet mechanical heart valve implanted at different orientations in an anatomic left ventricle-aorta obtained from magnetic resonance imaging of a volunteer. The thoroughly validated overset curvilinear-immersed boundary fluid-structure interaction flow solver is used in which the aorta and left ventricle (LV) are discretized with boundary-conforming and nonconforming curvilinear grids, respectively. The motion of the left ventricle wall is prescribed based on a lumped parameter model while the motion of the leaflets is calculated using a strongly coupled fluid-structure interaction algorithm enhanced with Aitken convergence technique. We carried out simulations for three valve orientations, which differ from each other by 45 deg, and compared the leaflet motion and flow field for multiple cycles. Our results show reproducible and relatively symmetrical opening for all valve orientations. The presence of small-scale vortical structures after peak systole causes significant cycle-to-cycle variations in valve kinematics during the closing phase for all valve orientations. Furthermore, our results show that valve orientation does not have a significant effect on the distribution of viscous shear stress in the ascending aorta. Additionally, two different mathematical activation models including linear level of activation and Soares model are used to quantify the platelet activation in the ascending aorta. The results show that the valve orientation does not significantly affect (less than 8%) the total platelet activation in the ascending aorta.

Mode competition in a plunging foil with an active flap: A multiscale modal analysis approach

Controlling flow-induced fluttering with morphing surfaces has long been a practical solution. However, the background knowledge of how the structure interacts with the flow has been lacking. Using a tightly-coupled fluid-structure interaction algorithm that utilizes conformal mapping techniques to provide geometrical weighting for multiscale decomposition, we isolate the dynamic effects caused by the surface motion and the flow. The energy ratio between the two effects is proven to be a good indicator of the control efficacy of the morphing flap.

Residual axial capacity of circular reinforced concrete columns subjected to contact explosions

The threat of terrorist bombing attacks on critical infrastructure has attracted a lot of attentions over the past decades. Contact explosion with a small explosive charge mass can cause severe damage to RC columns. Since columns are the primary load-bearing components in structures, the failure of critical columns can initiate collapse of the entire structure and result in devastating consequences associate with significant casualties and economic losses. To prevent catastrophic structural collapse, the most critical requirement of blast-damaged columns would be the residual capacity to withstand axial load. In this study, the residual axial load-carrying capacity of RC columns damaged by contact explosions was numerically investigated. A high-fidelity physics-based numerical model of RC columns under contact explosions was developed using the non-linear dynamic analysis program LS-DYNA with Arbitrary-Lagrangian–Eulerian (ALE) and Fluid-Structure Interaction (FSI) algorithms. The numerical model was comprehensively validated with existing experimental results in literature. An extensive parametric study was carried out to determine the effect of critical design parameters, including explosive charge mass, column diameter, longitudinal reinforcement ratio, and transverse reinforcement ratio on the residual axial load-carrying capacity of RC columns after contact explosions. The damage degree of the blast-damaged columns was quantitatively analyzed with a damage criterion based on the residual axial load-carrying capacity. Based on the parametric analysis results, an empirical formula was developed through multivariable regression analysis method for prediction of the damage degree and residual axial load-carrying capacity of blast-damaged RC columns under contact explosions. The proposed empirical formula can be utilized in preliminary design of RC columns against contact explosions and failure risk assessment of RC columns after contact explosions.

A mid-fidelity numerical method for blood flow in deformable vessels

In this work, a novel fluid–structure interaction algorithm for the simulation of blood flow in three-dimensional deformable vessels is addressed. The method extends the mid-fidelity strategy named as Transversally Enriched Pipe Element Method, extensively tested as an efficient approach to simulate the blood flow under rigid wall hypothesis, by taking into account the distensibility of the lumen boundary by means of an independent ring structural model. The Navier–Stokes equations, in Arbitrary Lagrangian–Eulerian framework, are used as the governing equations for the blood flow dynamics, the vessel wall mechanics is represented through an elastic constitutive law, and the fluid domain deformation problem is explicitly solved by exploiting the layered structure of the geometry discretization associated to the mid-fidelity model. The result is an approximation strategy able to take into account the wall deformation at nearly zero added cost when compared with a rigid wall model. An extensive numerical validation and verification of the proposed methodology is reported employing simple domains and complex patient-specific geometries to highlight the potential for real applications.