Fluid-structure Interaction Method Research Articles

Structural integrity assessment and optimization of control surfaces in coaxial unmanned aerial vehicles: A case study of a micro coaxial UAV

Unmanned aerial vehicles (UAVs) play a pivotal role in modern society which requires lightweight yet robust structures to fulfill increasingly complex tasks. This study presents a cost-effective prototyping approach to assess the structural integrity of control surfaces within the innovative Coaxial Unmanned Aerial Vehicle version 3.0 (MCR UAV v3.0). Integrating a hybrid design with coaxial propulsion for vertical stabilization and yaw control, the MCR UAV v3.0 incorporates control surfaces (ailerons) to manage roll and pitch movements during flight. The design process relies on a comprehensive understanding of material mechanical properties, particularly polylactic acid (PLA) specimens fabricated via fused deposition modeling (FDM) with varying infill percentages and building angles. A novel fluid-structure interaction method is developed in order to analyze four control surface topologies: concave (A), optimized concave (B), convex (C), and optimized convex (D). Findings reveal that the optimized design significantly improves stress distribution in the fuselage-control surface interface while reducing aileron weight by approximately 70%. Subsequently, a functional UAV prototype incorporating optimized ailerons is manufactured. Flight tests affirm the efficacy of the ailerons in controlling roll and pitch motions. This work significantly contributes by introducing the novel MCR UAV v3.0 and conducting a comprehensive assessment of fuselage-control surface structural stability, offering insights into enhanced UAV design and performance for diverse applications.

Computational Fluid–Structure Interaction in Microfluidics

Micro elastofluidics is a transformative branch of microfluidics, leveraging the fluid–structure interaction (FSI) at the microscale to enhance the functionality and efficiency of various microdevices. This review paper elucidates the critical role of advanced computational FSI methods in the field of micro elastofluidics. By focusing on the interplay between fluid mechanics and structural responses, these computational methods facilitate the intricate design and optimisation of microdevices such as microvalves, micropumps, and micromixers, which rely on the precise control of fluidic and structural dynamics. In addition, these computational tools extend to the development of biomedical devices, enabling precise particle manipulation and enhancing therapeutic outcomes in cardiovascular applications. Furthermore, this paper addresses the current challenges in computational FSI and highlights the necessity for further development of tools to tackle complex, time-dependent models under microfluidic environments and varying conditions. Our review highlights the expanding potential of FSI in micro elastofluidics, offering a roadmap for future research and development in this promising area.

Computational Fluid–Structure Interaction in Microfluidics

Micro elastofluidics is a transformative branch of microfluidics, leveraging the fluid–structure interaction (FSI) at the microscale to enhance the functionality and efficiency of various microdevices. This review paper elucidates the critical role of advanced computational FSI methods in the field of micro elastofluidics. By focusing on the interplay between fluid mechanics and structural responses, these computational methods facilitate the intricate design and optimisation of microdevices such as microvalves, micropumps, and micromixers, which rely on the precise control of fluidic and structural dynamics. In addition, these computational tools extend to the development of biomedical devices, enabling precise particle manipulation and enhancing therapeutic outcomes in cardiovascular applications. Furthermore, this paper addresses the current challenges in computational FSI and highlights the necessity for further development of tools to tackle complex, time-dependent models under microfluidic environments and varying conditions. Our review highlights the expanding potential of FSI in micro elastofluidics, offering a roadmap for future research and development in this promising area.

A two-way coupled fluid–structure interaction method for predicting the slamming loads and structural responses on a stiffened wedge

Ships navigating through rough seas are subjected to slamming loads from waves, which can lead to structural damage and maritime accidents. The wedge model is commonly employed to investigate slamming loads and structural responses. While a stiffened wedge closely resembles a real ship hull plate, incorporating it into fluid–structure interaction simulations presents challenges. This paper proposes a two-way coupled fluid–structure interaction method to examine slamming loads and structural responses of a free fall non-prismatic stiffened steel wedge. Hydrodynamic loads are determined through Reynolds-averaged Navier–Stokes computations using OpenFOAM, while structural responses are predicted using the finite element analysis (FEA) software Calculix. To achieve two-way coupling between computational fluid dynamics and FEA simulations, a coupling library for partitioned multi-physics simulations, preCICE, is introduced. The computed impact pressure and stress align well with available experimental data. Various free fall heights are investigated in the numerical simulations. The results indicate that elastic deformation mitigates impact pressure, while the presence of transverse ribs enhances the rigidity of the flexible plate. The duration of pressure and the peak slamming pressure exhibit an inverse correlation. Greater free fall heights result in shorter pressure duration times, and smaller free fall heights may reduce rise time. Three-dimensional effects cause pressure to decrease along the midpoint of the plate toward both sides. Additionally, structural stress in the central area exceeds that in the areas on both sides at the same height. In conclusion, the proposed two-way coupled model proves suitable for accurately and efficiently computing hydroelastic slamming on flexible wedges.

Study of the tumor effect on airflow in human upper airway exhalation using fluid-structure interaction method

Study of the tumor effect on airflow in human upper airway exhalation using fluid-structure interaction method

Prediction of erosion defects and buckling pressure of pipe bend based on bidirectional fluid-structure interaction method

In this study, a bidirectional fluid-structure interaction (FSI) method was proposed based on dynamic mesh technology to calculate the erosion defects of pipe bends under high pressure. In calculating the erosion rate of pipe bends, a stress erosion model was adopted, and the displacement and stress of the inner wall of pipe bend under high external pressure were considered. The influence of different parameters on the calculation results of erosion depth was discussed, and the buckling pressure and collapse mode of pipe bend under the erosion defect of liquid-solid flow were also studied. The proposed method can be used for predicting pipeline erosion defects under high pressure and evaluating the remaining limit load of pipelines with such erosion defects.

Transient dynamic stress behavior analysis of the axial flow pump as turbine at part loads

To explore the structural dynamic characteristics of the impeller and shaft system of the axial flow pump as turbine, the variation law of impeller transient equivalent stress, deformation, and the impeller and shaft system mode are analyzed by the transient fluid-structure interaction method. Findings indicate that the equivalent stress is centralized at the blade root around the hub and tends to decrease as it moves towards the shroud. The maximum equivalent stress at 1.0Qbep and 1.1Qbep is 1.26 times and 2.0 times higher than that at 0.8Qbep. Blade deformation is significantly influenced by flow rate. The maximum deformation of the blade at 1.0Qbep and 1.1Qbep is 1.6 times and 3.6 times higher than that at 0.8Qbep. The impeller and shaft system with prestress in dry mode has an average natural frequency of the first 10 orders that is 16.7 Hz higher than without prestress. However, with the fluid adding mass and flow damping, the average natural frequency of the first 10 orders of the impeller and shaft system in wet mode is reduced by 278.08 Hz compared with dry mode. In fact, the impeller and shaft system of the axial flow pump as turbine is not prone to vibration.

Patient-Specific Numerical Simulations of Coronary Artery Hemodynamics and Biomechanics: A Pathway to Clinical Use.

Numerical models that simulate the behaviors of the coronary arteries have been greatly improved by the addition of fluid-structure interaction (FSI) methods. Although computationally demanding, FSI models account for the movement of the arterial wall and more adequately describe the biomechanical conditions at and within the arterial wall. This offers greater physiological relevance over Computational Fluid Dynamics (CFD) models, which assume the walls do not move or deform. Numerical simulations of patient-specific cases have been greatly bolstered by the use of imaging modalities such as Computed Tomography Angiography (CTA), Magnetic Resonance Imaging (MRI), Optical Coherence Tomography (OCT), and Intravascular Ultrasound (IVUS) to reconstruct accurate 2D and 3D representations of artery geometries. The goal of this study was to conduct a comprehensive review on CFD and FSI models on coronary arteries, and evaluate their translational potential. This paper reviewed recent work on patient-specific numerical simulations of coronary arteries that describe the biomechanical conditions associated with atherosclerosis using CFD and FSI models. Imaging modality for geometry collection and clinical applications were also discussed. Numerical models using CFD and FSI approaches are commonly used to study biomechanics within the vasculature. At high temporal and spatial resolution (compared to most cardiac imaging modalities), these numerical models can generate large amount of biomechanics data. Physiologically relevant FSI models can more accurately describe atherosclerosis pathogenesis, and help to translate biomechanical assessment to clinical evaluation.

Vortex-induced vibration effect on the aeroelastic stability of two composite cylindrical shells using a fluid-structure interaction method

The purpose of this study, is to investigate the aeroelastic stability and effect of vortices resulting from passing air over cylindrical shells in three-dimensional condition. Here, the Naiver-Stokes equations in the integral form are considered studying the air flow based on the finite-volume method. The ANSYS Fluent software is used to study the fluid-solid interaction effect. The shear stress transport (SST) turbulence model is utilized to simulate the turbulent viscosity. Effect of different parameters such as two cylindrical shells alignment or two cylinders diameter ratio are considered. The results indicate that the vortices can play a significant role on the aeroelastic stability of the cylindrical shell.

Analysis of dynamic characteristics of whipping effect on l-shaped main steam pipe considering fluid-structure interaction effect

To investigate the whipping effect on the L-shaped main steam pipe utilized in the marine steam systems, the fluid-structure interaction (FSI) method is utilized to numerically analyze its dynamic characteristics. The numerical results illustrate that the dynamic response of whipping effect with rupture position B on the oblique pipe section is more severe with the significantly larger displacement of L-shaped pipe and anti-whip restraints and more complex frequency characteristics than that of whipping effect with rupture position A on the right-angled elbow. The mode transition phenomenon is also observed in the case with rupture position B. The maximum deformation concentrates on different parts when burst of pipes occurs at different positions and the deformation with rupture position B is several times larger than that with rupture position A. The increase of gap between anti-whip restraints intensifies the whipping effect, but it also reduces the maximum restraint force. The friction acts as the resistance in the slip process and thus contributes to the protection against whipping effect. The anti-whip restraints E closed to rupture position B on the oblique pipe section has better performance than anti-whip restraints D in the protection against horizontal whipping effect.

In silico analysis of embolism in cerebral arteries using fluid-structure interaction method

Ischemic stroke, particularly embolic stroke, stands as a significant global contributor to mortality and long-term disabilities. This paper presents a comprehensive simulation of emboli motion through the middle cerebral artery (MCA), a prevalent site for embolic stroke. Our patient-specific computational model integrates major branches of the middle cerebral artery reconstructed from magnetic resonance angiography images, pulsatile flow dynamics, and emboli of varying geometries, sizes, and material properties. The fluid-structure interactions method is employed to simulate deformable emboli motion through the middle cerebral artery, allowing observation of hemodynamic changes in artery branches upon embolus entry. We investigated the impact of embolus presence on shear stress magnitude on artery walls, analyzed the effects of embolus material properties and geometries on embolus trajectory and motion dynamics within the middle cerebral artery. Additionally, we evaluated the non-Newtonian behavior of blood, comparing it with Newtonian blood behavior. Our findings highlight that embolus geometry significantly influences trajectory, motion patterns, and hemodynamics within middle cerebral artery branches. Emboli with visco-hyperelastic material properties experienced higher stresses upon collision with artery walls compared to those with hyperelastic properties. Furthermore, considering blood as a non-Newtonian fluid had notable effects on emboli stresses and trajectories within the artery, particularly during collisions. Notably, the maximum von Mises stress experienced in our study was 21.83 kPa, suggesting a very low probability of emboli breaking during movement, impact, and after coming to a stop. However, in certain situations, the magnitude of shear stress on them exceeded 1 kPa, increasing the likelihood of cracking and disintegration. These results serve as an initial step in anticipating critical clinical conditions arising from arterial embolism in the middle cerebral artery. They provide insights into the biomechanical parameters influencing embolism, contributing to improved clinical decision-making for stroke management.

Assessing the influence of aneurysm dimensions on hemodynamic patterns and wall deformation dynamics for predicting rupture risk

Cerebral aneurysms are among the most dangerous cardiovascular diseases which display no symptoms prior to reaching critical conditions. As cerebral aneurysms are deadly diseases with a very small treatment window after reaching the critical stage, numerical investigations of this phenomenon are commonly used to assess the risk of rupture. In this study, the fluid-structure interaction (FSI) method is used to analyze the effects of aneurysm size on hemodynamic factors predicting rupture in three aneurysms of different geometries, at the same location, and using the same boundary conditions. In the present study, the aneurysms experience TAWSS at values under 2 Pa in incremented areas as the aneurysmal sizes increase, this is while the relatively larger distribution of high TAWSS (as high as 20 Pa) regions are perceived in smaller aneurysms. Furthermore, the maximum OSI stands at below 0.05 in the smaller cases while the larger case experiences a maximum OSI as high as 0.2, which is considered a predictive parameter for rupture. The vortex core lines experience discontinuities with increased aneurysmal size, which is in agreement with the development of flow complexities with size. The hemodynamics factors such as the time-averaged wall shear stress (TAWSS), oscillatory shear index (OSI), and vortex core line investigated in this study, suggest that greater size can be considered a major risk factor for rupture. In addition to that, we have found that the displacement trend of the aneurysm changes as size increases; developing more in the dome rather than the aneurysmal sac. This change in trend might also present a potential to be used as a predictive parameter.

One-Way Fluid–Structure Interaction Simulation of the Added Damping of T(0,1) Modes of Two Partially Overlapped Identical Plates in Still Water

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

Investigation of oblique water entry of high-speed supercavitating projectiles using transient fluid-structure interaction simulation

This study employs a fluid-structure interaction simulation to examine the structural deformation of supercavitating projectiles during high-speed oblique water entry. A cavitation flow field simulation model is established using the VOF multiphase and cavitation models, while the structural dynamics model of the projectile is implemented using the Johnson-Cook constitutive equation. The transient fluid-structure interaction simulation is conducted through data transfer between the two models. Numerical simulations are then conducted with the assumptions of a rigid body, linear elasticity, and nonlinearity, respectively. The results indicate that the high-speed water entry induced substantial hydrodynamic force and plastic strain accumulation in the projectile, leading to considerable bending deformation. It was found that the deformation significantly influenced the hydrodynamic forces, highlighting the importance of fluid-structure interaction modeling. Moreover, the attack angle directly impacts the resulting deformation mode. Specifically, under high-speed conditions, three distinct deformation modes are observed at different attack angles: minimal deformation at low angles, an L-shaped bending at higher angles, and an S-shaped bending when the angle exceeds the threshold. This study highlights the importance of fluid-structure interaction methods in analyzing the deformation behavior of supercavitating projectiles during high-speed oblique water entry. The results show that the bidirectional dynamic interaction between fluid and structure significantly influences the structural stability of the supercavitating projectiles. The relevant conclusions can provide a reference for the optimal design of supercavitating projectiles to ensure the structural stability under high-speed conditions.

NGHIÊN CỨU TRƯỜNG ỨNG SUẤT BÁNH CÔNG TÁC TẦNG ĐẦU TIÊN MÁY NÉN ĐỘNG CƠ TUA BIN KHÍ TV3-117 BẰNG MÔ PHỎNG SỐ

This article presents the results of stress field calculations for the first stage compressor impeller using the one-way fluid-structure interaction (FSI) method, which helps determine stress concentration zones and safety factors. Numerical analysis conducted with Ansys software reveals that stress concentration occurs near the blade root on the suction side and within the blade lock-disc zone. In these stress concentration zones, such as the blade lock-disc zone and blade suction side, the minimum safety factor is found to be above 2.27. These findings serve as a foundation for future research on impeller stress fields using two-way FSI methods and for providing recommendations to optimize the stress concentration field in the compressor disc.

A Flow Structure Interaction Method for Towed Cable System

Abstract: The ocean towed cable system is a classic example of fluid-structure interaction (FSI). This interaction can exhibit stability or oscillation between a highly deformable moving cable and the surrounding turbulent flow. However, in dynamic simulations of towed cable systems, a constant drag coefficient for an infinite circular cylinder is often used based on experimental data. An innovative fluid-structure interaction method is introduced to obtain accurate drag distribution along cable to couple with towed system dynamics. A modified nodal position finite element method (NPFEM) coupled with Reynolds-averaged Navier-Stokes (RANS) approach has been utilized to predict hydrodynamic forces along the cable. A data exchange algorithm has been developed specifically for fluid-structure interaction within the towed cable system where the cable profile is transferred to construct the flow domain while hydrodynamics is interpolated for NPFEM analysis. A topology partition around cable is applied. A multiblock grid is generated around cable. The simulation results of the fluid-structure interaction of the towing system are verified. This FSI scheme reveals how strongly hydrodynamics determine cable dynamics and induce vortex structure vibrations around a towed cable system. Parametrically controlled structured grid generation and their applicability for complex flow fields have also been discussed. Detailed descriptions of boundary layer separation evolution around spatially distributed cable are provided. This FSI scheme reveals a real strongly hydrodynamic determined cable dynamics and vortex structure induced vibrations around a towed cable system. The proposed method enhances predictive accuracy of the towed system dynamics response.

The European GO-VIKING project on flow-induced vibrations: overview and current status

Abstract The interaction between cooling fluid and solid structures (rods, tubes) in nuclear power plants may lead to flow-induced vibrations (FIV), causing material fatigue, fretting wear, and eventually loss of component integrity. This can cause further safety issues as well as substantial standstill costs due to longer or unplanned outages. With the growing computational power, the application of modern 3D numerical simulation tools for the accurate prediction of FIV phenomena is rapidly increasing. In 2022, the GO-VIKING (Gathering expertise On Vibration ImpaKt In Nuclear power Generation) project received a grant within the Horizon Europe research and innovation funding program. Sixteen European and two US partners started their collaboration in the field of FIV experiments and analysis. Over four years, the GO-VIKING project investigates FIV phenomena occurring in nuclear reactor cores and steam generators under single- and two-phase flow conditions. The project’s main objectives are to expand the expertise in the field of FIV through generation of new experimental and high-resolution numerical data; development, improvement, and validation of fluid-structure interaction (FSI) methods for FIV evaluation; training stakeholders in the application of these methods; and synthesizing guidelines for the prediction and assessment of FIV phenomena in nuclear reactors. This paper provides an overview of the GO-VIKING objectives, scientific program, as well as of the main scientific achievements in the first project year.

Design, Optimization, and Modeling of a Hydraulic Soft Robot for Chronic Total Occlusions.

Chronic total occlusion (CTO) is one of the most severe and sophisticated vascular stenosis because of complete blockage, greater operation difficulty, and lower procedural success rate. This study proposes a hydraulic-driven soft robot imitating the earthworm's locomotion to assist doctors or operators in actively opening thrombi in coronary or peripheral artery vessels. Firstly, a three-actuator bionic soft robot is developed based on earthworms' physiological structure. The soft robot's locomotion gait inspired by the earthworm's mechanism is designed. Secondly, the influence of structure parameters on actuator deformation, stress, and strain is explored, which can help us determine the soft actuators' optimal structure parameters. Thirdly, the relationship between hydraulic pressure and actuator deformation is investigated by performing finite element analysis using the bidirectional fluid-structure interaction (FSI) method. The kinematic models of the soft actuators are established to provide a valuable reference for the soft actuators' motion control.

Investigating a hermetic reciprocating compressor performance under variable lift limiter height using FSI method

This study examines discharge line energy losses using advanced fluid-structure interaction methods to show how valve design parameters—length, thickness, and height—improve compressor performance. An innovative 3D fluid-structure Interaction model represents a self-acting hermetic reciprocating compressor's discharge valve as a beam element. The RNG k− ε model examines how reed valve thickness, length, compressor speed, and lift limiter height impact pressure pulsation and compressor efficiency. Under ASHRAE conditions, operating at a challenging temperature range of 54.4 to −23.3 °C, the study meticulously explores the intricate interplay of discharge valve characteristics. Specifically, varying valve thicknesses (0.127, 0.152, 0.178, and 0.2 mm) and lengths (14.722, 16.222, and 17.722 mm) are examined in conjunction with different compressor speeds (1300, 2100, and 3000 rpm) according to the design specifications. Upon meticulous examination of discharge line losses at a compressor speed of 1300 rpm, intriguing insights emerged. For lift limiter heights of 0.8, 1.05, and 1.25 mm, coupled with a valve length of 17.722 mm, the study unveiled remarkable average energy losses of −6.91%, 2.83%, and −8.52%, respectively. The exploration continued at 2100 rpm, revealing a dynamic pattern with average losses for the same lift limiter heights at 0.94%, −1.26%, and −4.43%, respectively. In a succinct summary, the valve in focus demonstrated a noteworthy disparity in discharge line losses, reaching a maximum variation of 9.15%, −3.83%, and −8.30% when operated at the challenging speed of 3000 rpm.

Prediction of performance parameters of a hermetic reciprocating compressor applying an artificial neural network

The efficiency of the compressor's thermodynamic, mechanical, and electric motors can be increased by minimizing their losses. Based on the design characteristics of the compressor, the current study proposes an artificial neural network (ANN) model to forecast the mass flow rate, cooling capacity, compression power, and discharge line loss of the hermetic reciprocating compressor as outputs. This study uses experimental and numerical results obtained by the fluid–structure interaction (FSI) method, and the whole findings are used as inputs for the machine learning method. Using 36 numerical and 3 experimental data sets, a multilayer network is created with input parameters defining mass flow rate, cooling capacity, compression power, and discharge line energy loss. The input parameters for the network model are the compressor's design parameters, which include the compressor speed, discharge valve thickness, and discharge valve length. When comparing the experimental and FSI methods for compressor speeds of 1300, 2100, and 3000 rpm, the FSI study's mass flow rate and cooling capacity parameters converged at 11.9%, 9.1%, and 9.3%, respectively, to their actual values. The convergence rate to experimental compression power data was −0.3%, 2.6%, and 11%. The numerical-experimental deviation for discharge line energy losses is 14.9%, −3.6%, and 7.8%, respectively, for 1300, 2100, and 3000 rpm. With the Levenberg–Marquardt (LM) ANN model, which is used in this study, the average squared error value is calculated as 1.75E-02 and the R2 value is calculated as 0.99976. ANN model can predict outputs with average deviation rates of less than 0.88%. It is seen that results obtained with the ANN method provide high convergence on the experimental and FSI results, while the results obtained with the regression model deviate from the compressor exhaust line results by more than ±20%, and the ANN method is more successful than regression.