Fluid-structure Interaction Analysis Research Articles

Design and fluid-structure interaction analysis for a microfluidic T-junction with chemo-responsive hydrogel valves

Due to the deformation ability even under small loads, hydrogels have been widely used as a type of soft materials in various applications such as actuating and sensing, and have attracted many researchers to study their behaviors. In this paper, the behavior of hydrogel micro-valves with reverse sensitivity to the pH inside a T-junction flow sorter is investigated. With the fluid-structure interaction (FSI) approach, the effects of various parameters such as the inlet pressure and the pH value on the stress and deformation of the micro-valves are examined, and the results with and without FSI, including the flow rate and the closure pH, are compared. In order to reduce the response time of hydrogels, the effects of three different patterns on the performance of the micro-valves are explored. Eventually, it is concluded that FSI is a key influential factor in designing and analyzing the behaviors of hydrogels.

Fluid–structure interaction in Z-shaped pipe with different supports

Fluid–structure interaction (FSI) has a strong relation with layout of fluid delivery system. FSI is liable to cause local damage. Thus, FSI analysis is necessary in many cases, especially for flexible pipe systems. FSI modeling consists of eight governing equations and then completely solved via the finite volume method (FVM). Friction, Poisson and joint couplings were discussed in detail to reveal the influence of a Z-shaped pipe with different supports and elbows on FSI. After the feasibility of solving FSI by FVM was verified, the different effects of free, fixed and elastic supports on FSI in the commonly used and simplified Z-shaped pipe were further analyzed. Results indicated that different support stiffness lead to various FSI responses. If coupling occurs at the elbow and less support is considered, then the pipe has a relatively large amplitude and complex pressure fluctuation.

Effects of blood flow patent and cross-sectional area on hemodynamic into patient-specific cerebral aneurysm via fluid-structure interaction method: A review

Fluid-structure interaction (FSI) simulation is carried out to investigate the blood flow analysis in different patient-specific cerebral aneurysms. In this study, we reviewed the studies done on the numerical simulation of blood flow in patient-specific aneurysm by using FSI analysis methods. Based on these studies, the wall shear stress (WSS) plays an important role in the development, growth, and rupture of the cerebral aneurysm. Prediction of the hemodynamic forces near the aneurysmal site helps to understand the formation and rupture of the aneurysms better. Then most of the aneurysms studied are located in the middle cerebral artery (MCA). In the existing considered, many researchers are more familiar with the experimental method in studies of blood flow through cerebral aneurysm compared to the numerical method. Nevertheless, numerical simulation of patient-specific cerebral aneurysms can give a better understanding and clear visualization of WSS distribution and fluid flow pattern in the aneurysm region.

Fluid–Structure Interaction Based on Meshless Local Petrov–Galerkin Method for Worm Soft Robot Analysis

The purpose of this study was to develop a two-way fluid–structure interaction (FSI) method using the meshless local Petrov–Galerkin (MLPG) method for both the structure and the fluid to accurately predict the nonlinear behavior of a worm soft robot. Previous research on soft robots has been mainly performed by finite element analysis (FEA). However, the nonlinear behavior of a soft robot causes element distortion and discontinuous stress between the adjacent elements, even when adaptive mesh is employed in the FEA. Therefore, MLPG was employed here to precisely predict the nonlinear behavior of a soft robot without using finite elements. In addition, a pneumatic soft robot simulation requires two-way FSI analysis that can transmit and receive data between the fluid and the structure, and the structure and the fluid, in sequence. To improve accuracy for the interface, the arbitrary Lagrangian–Eulerian method and the level set method were applied here. It was verified that the maximum errors of the finite element method FSI and the developed MLPG FSI method were 4.69%, and 0.77%, respectively, and the latter method required fewer nodes than FEM.

Numerical evaluation of transcatheter aortic valve performance during heart beating and its post-deployment fluid-structure interaction analysis.

Transcatheter aortic valve replacement (TAVR) is a minimally invasive procedure that provides an effective alternative to open-heart surgical valve replacement for treating advanced calcific aortic valve disease patients. However, complications, such as valve durability, device migration, paravalvular leakage (PVL), and thrombogenicity may lead to increased overall post-TAVR morbidity and mortality. A series of numerical studies involving a self-expandable TAVR valve were performed to evaluate these complications. Structural studies were performed with finite element (FE) analysis, followed by computational fluid dynamics (CFD) simulations, and fluid-structure interaction (FSI) analysis. The FE analysis was utilized to study the effect of TAVR valve implantation depth on valve anchorage in the Living Heart Human Model, which is capable of simulating beating heart during repeated cardiac cycles. The TAVR deployment cases where no valve migration was observed were then used to calculate the post-deployment thrombogenic potential via CFD simulations. FSI analysis followed to further assess the post-deployment TAVR hemodynamic performance for different implantation depths. The deployed valves PVL, geometric and effective orifice areas, and the leaflets structural and flow stress magnitudes were compared to determine the device optimal landing zone. The combined structural and hemodynamic analysis indicated that with the TAVR valve deployed at an aft ventricle position an optimal performance was achieved in the specific anatomy studied. Given the TAVR's rapid expansion to younger lower-risk patients, the comprehensive numerical methodology proposed here can potentially be used as a predictive tool for both procedural planning and valve design optimization to minimize the reported complications.

Open-source immersogeometric analysis of fluid–structure interaction using FEniCS and tIGAr

We recently developed the open-source library tIGAr, which extends the FEniCS finite element automation framework to isogeometric analysis. The present contribution demonstrates the utility of tIGAr in complex problems by applying it to immersogeometric fluid–structure interaction (FSI) analysis. This application is implemented as the new open-source library CouDALFISh (Coupling, via Dynamic Augmented Lagrangian, of Fluids with Immersed Shells, pronounced “cuttlefish”), which uses the dynamic augmented Lagrangian (DAL) method to couple fluid and shell structure subproblems. The DAL method was introduced previously, over a series of papers largely focused on heart valve FSI, but an open-source implementation making extensive use of automation to compile numerical routines from high-level mathematical descriptions brings newfound transparency and reproducibility to these earlier developments on immersogeometric FSI analysis. The portions of CouDALFISh that do not use code generation also illustrate how a framework like FEniCS remains useful even when some functionality is outside the scope of its standard workflow. This paper summarizes the workings of CouDALFISh and documents a variety of benchmarks demonstrating its accuracy. Although the implementation emphasizes transparency and extensibility over performance, it is nonetheless demonstrated to be sufficient to simulate 3D FSI of an idealized aortic heart valve. Source code will be maintained at https://github.com/david-kamensky/CouDALFISh.

Investigation of duct augmented system effect on the overall performance of straight blade Darrieus hydrokinetic turbine

Power generation utilizing the kinetic energy of river flow, tidal, and ocean currents have encouraged the use of Darrieus turbines. However, the low power coefficient, poor self-starting characteristics, and lack of structural analysis have limited their usage. This study, as such, investigates the effect of a ducted augmented system on a Straight Blade Darrieus Hydrokinetic Turbine (SBDHT) to analyze performance, fluid loads, and stress-induced. A one-way Fluid-Structure Interaction (FSI) analysis followed the transfer of fluid forces to the structural module. Real-time hydraulic load and stress were computed and compared for ducted and non-ducted turbines. Computational Fluid Dynamic (CFD) analysis was performed to solve Reynolds Average Navier Stokes (RANS) equations, while turbulences were modeled using k−ω Shear Stress Transport (SST) model. CFD simulation revealed that, for the range of free stream velocity values, the duct augmentation system showed an increase in power production by 112% as compared to non-ducted turbines. The results also reveal that the ducted turbine will experience two-times the hydraulic loads in contrast to non-ducted turbines. Further, induced stress estimation revealed that 178.5 MPa and 94.68 MPa stresses were induced on the ducted and non-ducted turbine, respectively. The stress analysis result showed that maximum stresses occur within the turbine arms and at the joint between shaft and arms. It is, therefore, concluded that the ducted turbine approximately generates double power; however, it also experiences nearly twice stresses compared to the non-ducted turbine, which shall although increase the material cost of the turbine. This study, therefore, recommends that the duct augmentation system should be preferred choice while carefully designing such a system.

FSI simulations for sailing yacht high performance appendages

ABSTRACT In an age where sailing boats are losing their reputation of slow-moving vehicles, and where technologies are developing at explosive rhythm, the scantling criteria are deeply changing and naval architects face new challenges. Beside a literature review on sailing yacht appendages design, the state of the art of the methods for fluid-elastic phenomena prediction is presented. To face the problem of numerical modelling, an overview on Fluid-Structure Interaction (FSI) numerical computational is provided, introducing the main parameters to care about while modelling the interaction of a hydro-foil with the flow. The software capabilities are explored, reporting the main steps to follow, in order to build both solid and fluid models of a hydrofoil, and to couple them in a FSI analysis. A suitable test case has been selected, providing numerical and experimental reference for outcomes comparisons. The results are presented focusing on tolerances, relaxation factors and time discretisation effect on the solution.

Fluid-Structure Interation of a Rigid Wing for Minesto Deep Green, a Tidal Energy Device

Fluid structure interaction (FSI) analysis has been performed on the main wing structure of an underwater renewable energy tidal flow device using methods of different fidelity. A lower fidelity method represented the wing as a series of beams (1D line elements) which deflect and rotate under hydrodynamic load. These deflections and rotations were used to update the geometry for the hydrodynamic model where updated forces and moments were calculated using potential flow theory with integral boundary layer (2D panel methods). The higher fidelity method represented the wing using a combination of 3D solid elements for the foam structure inside the wing and 2D shell elements for the carbon fibre wing stiffening beams and fibre glass wing skin. The results of a modal analysis of the wing structure were used in a 3D CFD simulation that coupled the modal equations with the Navier-Stokes equations to compute the deformed shape of the wing under hydrodynamic load. In both cases, the maximum deformations of the wing were quite small (<25mm) compared to the wing size (12m span, 3.3m maximum chord) but the effect on hydrodynamic characteristics was quite different. The low fidelity analysis made the assumption that the wing cross-sectional shape profile did not change, although it could move and rotate. There was no significant change in the predicted hydrodynamic characteristics between the deformed and undeformed wing shapes. The contribution of the foam to the stiffness of the wing was not included in the low fidelity analysis as it was thought to be minor contributor due the much lower Young’s Modulus compared to the carbon fibre and fibre glass of the main wing structure. In contrast, the high fidelity method resulted in about a 15% reduction in lift and 6% in drag forces due to deformation of the wing cross-section profiles rather than bending and twisting of the wing which the low fidelity analysis showed not to be significant. The effect on energy yield of these changes is estimated to be very small.

Analysis of power law fluid-structure interaction in an open trapezoidal cavity

The present paper investigates the mixed convection heat transfer of non-Newtonian fluid-structure interaction (FSI) inside an open trapezoidal cavity. The base of the cavity is fixed at constant temperature while the other walls are adiabatic. The flow passes over the open side of the cavity through a parallel-plate channel. An elastic fin is dangled from the top wall of the channel and stand facing the open cavity. The current model presents a two- dimensional incompressible laminar flow and unsteady-state conditions using the non-Newtonian power- law fluids. Numerical simulation is achieved using finite element method with arbitrary Lagrangian–Eulerian (ALE) scheme. The effects of Cauchy number, Reynolds number, Richardson number and the index of power law fluid are examined with ranges of (Ca = 10−20–10−3, Re = 100–300, Ri = 0.01–10 and n = 0.5–1.5). The results show that at Re = 300, Nusselt number of a stiff fin is 2.6% and 7% higher than that of softer flexible fin for n = 0.5 and 1.5, respectively. For low Ri number, shear-thickening fluid manifests higher Nusselt number while for high Ri number, the shear-thinning fluid has the higher values. It is found also that the fluttering phenomenon of the fin takes place at the highest Ri and Re numbers with shear-thinning fluid and Newtonian fluid as well.

Prediction of aeroelastic response of bridge decks using artificial neural networks

The assessment of wind-induced vibrations is considered vital for the design of long-span bridges. The aim of this research is to develop a methodological framework for robust and efficient prediction strategies for complex aerodynamic phenomena using hybrid models that employ numerical analyses as well as meta-models. Here, an approach to predict motion-induced aerodynamic forces is developed using artificial neural network (ANN). The ANN is implemented in the classical formulation and trained with a comprehensive dataset which is obtained from computational fluid dynamics forced vibration simulations. The input to the ANN is the response time histories of a bridge section, whereas the output is the motion-induced forces. The developed ANN has been tested for training and test data of different cross section geometries which provide promising predictions. The prediction is also performed for an ambient response input with multiple frequencies. Moreover, the trained ANN for aerodynamic forcing is coupled with the structural model to perform fully-coupled fluid–structure interaction analysis to determine the aeroelastic instability limit. The sensitivity of the ANN parameters to the model prediction quality and the efficiency has also been highlighted. The proposed methodology has wide application in the analysis and design of long-span bridges.

Fluid structure interaction analysis of flexible beams vibrating in a time-varying fluid domain

In this work, the transversal vibration of a submerged cantilever beam is studied with a time-varying fluid domain taken into consideration. The elastic beam is modeled using the Euler–Bernoulli beam theory, and the fluid is simplified by potential fluid theory. The governing equations of this fluid-structure interaction system are obtained using the mode superposition method and Galerkin’s method. Then the influence of the time-varying fluid is investigated in detail, based on modal analysis and transient analysis. Time-frequency analysis is given for signal processing of the obtained response, as the frequencies are time-varying. The analytical results obtained in this paper show good agreement with numerical results by ANSYS and results in the previous study. This study reports a new phenomenon that changing of the fluid induces an additional nonstructural damping, which is proportional to the velocity of the depth changing of the fluid. The induced damping influences vibration of the beam significantly and must be taken into account in dynamic analysis of structures in a time-varying fluid.

Fatigue Life Assessment of KC-1 Membrane Considering the Effects of Cryogenic Temperature and Plastic Deformation

In this study, fatigue life assessment was conducted on a KC-1 membrane, considering cryogenic operation temperature, effect of stamping, and very long service period. KC-1 membranes are produced through a process of stamping, and they make direct contact with LNG filled within a containment system at − 162 °C. The high waves that LNG carriers encounter during sailing, and even when at anchor, cause rolling motions of the hull, which result in resonant fluid motions that generate a sloshing phenomenon; such sloshing motions expose containment systems to a high level of repeated stress. To assess the very high cycle fatigue (VHCF) life of the membrane, the effects of plastic deformation and the mechanical properties of STS304L, a membrane material, were examined at cryogenic temperatures. To identify the effects of plastic deformation and cryogenic temperatures on their mechanical properties, tensile and VHCF tests were conducted at cryogenic temperatures on a sheet to which plastic strain was applied through cold-rolling. Through forming analysis, changes in the thickness and plastic strain of a membrane caused during the process of stamping were examined. The results of earlier studies that performed flow analysis and fluid–structure interaction analysis to measure the stress applied to each component of the KC-1 containment system were cited, and the VHCF life of the membrane was assessed based on the surveyed mechanical properties, and the results of forming analysis.

Effect of Aortic Wall Deformation with Healthy and Calcified Annulus on Hemodynamic Performance of Implanted On-X Valve.

In this research, the hemodynamic performance of a 23-mm On-X bileaflet mechanical heart valve (BMHV) was investigated with the realistic geometry model of the valve and the deformable aorta in accelerating systole. In addition, the effect of ascending aorta flexibility and aortic annulus calcification on the complex blood flow characteristics were investigated. The geometry of the aorta is derived from the medical images, and the Ogden model has been utilized for the mechanical behavior of the ascending aorta. The 3D numerical simulation by a two-way Fluid-Structure Interaction (FSI) analysis using the Arbitrary Lagrangian-Eulerian (ALE) method was performed throughout the accelerating systolic phase. The dynamics of the leaflets are investigated, and blood flow characteristics such as velocities, vorticities as well as viscous and turbulent shear stress were precisely captured in the flow domain specifically in the hinge region. Streamline results are in accordance with the previously reported data, which show that the flared On-X valves inlet yields a more uniform flow in accelerating systole. Simulations show that aorta flexibility or valve annulus calcification causes variations up to 7% in maximum fluid velocity and 20% in Turbulence Kinetic Energy (TKE). In this study, the complex flow field characteristics in the new generation of BMHVs considering aorta flexibility with healthy and calcified annulus were investigated. It was found that the blood flow around the hinges region is in the danger of hemolysis and platelet activation and subsequently thromboembolism. Furthermore, the results show that similar to vessel wall deformation, considering the probable annulus calcification after valve replacement is also essential.

Design and thermal fluid structure interaction analysis of liquid nitrogen cryostat of cryogenic molecular sieve bed adsorber for hydrogen isotopes removal system

Efficient design of Tritium Extraction System (TES) for the fuel cycle of any fusion reactor is very important to maintain the tritium breeding ratio and hence sustain the fusion reaction. Hydrogen Isotopes Removal System (HIRS) for Indian Tritium Breeder Blanket removes Q2 (Q = H, D or T) and impurities using Cryogenic Molecular Sieve Bed (CMSB) adsorber at 77 K. The CMSB is maintained at liquid nitrogen temperature using a double walled cryostat made up of SS304. The paper describes the design and thermal Fluid Structure Interaction (FSI) analysis of cryostat assembly for CMSB of HIRS. The coupled analysis performed in this work involves solving for the fluid domain and transferring the results to ANSYS Thermal-Static structural set up to determine the stresses and displacement due to combined effects in the system. The mechanical design of the cryostat components is analytically performed using ASME codes. The velocity, pressure drop and time taken to cool the CMSB are determined by solving the fluid and energy equations in ANSYS Fluent analysis system. The solutions are imported into ANSYS Thermal-Static structural analysis system and the thermal-structural stresses and deformations are determined considering the temperature, pressure and acceleration loads. The space between inner and outer vessel is maintained at vacuum, which might lead to buckling. So, the critical buckling load multiplier factor is determined. These results are used in fabricating the complete cryostat system for CMSB of HIRS.

Prediction of a transformer vibration during excitation by fluid-structure interaction analysis

Prediction of a transformer vibration during excitation by fluid-structure interaction analysis

FSI analysis and simulation of flexible blades in a Wells turbine for wave energy conversion

In this paper a preliminary design and a 2D computational fluidstructure interaction (FSI) simulation of a flexible blade for a Wells turbine is presented, by means of stabilized finite elements and a strongly coupled approaches for the multi-physics analysis. The main objective is to observe the behaviour of the flexible blades, and to evaluate the eventual occurrence of aeroelastic effects and unstable feedbacks in the coupled dynamics. A series of configurations for the same blade geometry, each one characterized by a different material and mechanical properties distribution will be compared. Results will be given in terms of total pressure difference, supported by a flow survey. The analysis is performed using an in-house build software, featured of parallel scalability and structured to easy implement coupled multiphysical systems. The adopted models for the FSI simulation are the Residual Based Variational MultiScale method for the Navier-Stokes equations, the Total Lagrangian formulation for the nonlinear elasticity problem, and the Solid Extension Mesh Moving technique for the moving mesh algorithm.

One-way FSI analysis of bio-inspired flapping wings

Aerodynamics and structural dynamics of the insect wings are widely considered in flapping wing micro air vehicle (FWMAV) applications. In this paper, the aerodynamic characteristics of the three-dimensional flapping wing models mimicked from the bumblebee and hawkmoth wings are numerically investigated under steady flow conditions. This study aims to simulate the one-way fluid-structure interaction (FSI) of these bio-inspired wings by transferring the aerodynamic load obtained from the computational fluid dynamics (CFD) into the finite element method (FEM) solver as a pressure load. The static aeroelastic responses of the wings under the pressure load are compared for different materials, namely, cuticle, aluminium alloy, and titanium alloy at various angles of attack (α = 0°-90°). CFD analysis shows that the hawkmoth wing model at α = 5° has the highest lift-to-drag ratio (L/D). FSI analysis demonstrates that the cuticle hawkmoth wing model at α = 90° undergoes the highest tip deflection.

A study on prediction of whipping effect of very large container ship considering multiple sea states

In the design stage of the very large container ships, some methodologies for the whipping effects have been developed, but most of them are based on single sea state. We developed a methodology that considers multiple sea states. Fluid-structure Interaction (FSI) analyses with one dimensional structural model were carried out to capture slamming-induced transient whipping behaviors. Because of the nature of random phases of the applied wave spectra, the required period for entire FSI analyses was determined from the convergence study where the whipping effect became stable. Low pass filtering was applied to the transient whipping responses to obtain the hull girder bending moment processes. Peak counting method for the filtered whipping responses was used to obtain collection of the vertical bending moment peaks. The whipping effect from this new method is compared with that from based on single sea state approach. The efficiency and advantage of the new methodology are presented.

Fluid-structure interaction analysis for Martian exploration parafoil with deployable structure

Fluid-structure interaction analysis for Martian exploration parafoil with deployable structure