Two-way Fluid-structure Interaction Analysis Research Articles

Fluid–Structure Coupling and Aerodynamic Performance of a Multi-Dimensional Morphing Wing with Flexible Metastructure Skin

A multi-dimensional morphing wing skeleton mechanism is proposed with double-sided triangular pyramid units, which can realize continuous variable span-wise bend, span-wise twist, and sweep. A lockable morphing unit is designed, and its mechanism/structure characteristics, degree of freedom, and the deformable function of its deformable wing skeleton mechanism are analyzed. One kind of flexible skin is proposed to meet the performance requirements, consisting of an internal metastructure and a flexible surface bonded on both sides. The morphing wing skeleton mechanism and the equivalent treated metastructure flexible skin are then combined. Subsequently, a two-way fluid–structure interaction analysis is conducted to investigate the influence of aerodynamic loads on the flexible skin and skeleton mechanism in different deformation states, including the influence of structural passive deformation on the aerodynamic characteristics of the morphing wing. The computational fluid dynamics method is employed to analyze the aerodynamic characteristics of the morphing wing in its initial state, as well as in three deformation states, and to study its aerodynamic performance in different flight environments.

Effects of flexible fins on melting process in a phase change material filled circular cavity

In this study, melting process in a phase change material (PCM) filled annular closed space by using flexible fins is analyzed. Cases with different number of flexible fins and without fin are compared in terms of phase change dynamics while two-way fluid structure interaction analysis is used. Temperature differences of 30 °C and 60 °C are considered between the walls of the circular enclosure while flexible fin numbers are varied between 0 and 10. It is observed that the melting is significantly accelerated by using the elastic fins. Due to the deflection of the elastic fins, melt process dynamics is influenced by varying fin number and its elastic modulus. Further reduction in the full phase transition occurs when the temperature difference is increased. As compared to un-finned case at temperature difference of 30 °C by using 10 flexible fins at ∆T = 60 °C, there is 87 % reduction in the complete phase transition time. The ANFIS (Adaptive Neuro-Fuzzy Interface System) based modeling approach is used for phase transition dynamics in circular enclosure equipped with flexible fins.

Study on Dynamic Characterization and Vibration Reduction of Scrubber Structures Using Fluid Structure Interaction Analysis

A scrubber is an important structure in post-semiconductor processes. It is impossible to completely modify the entire structure of an already installed and operating scrubber if a vibration problem occurs. Therefore, it is essential to determine the cause of vibrations and reinforce the structure. Vibration is majorly caused by the pump, and as considerable vibration is generated around the pump, it is essential to analyze it. However, as various equipment is operated in buildings where scrubbers are installed, the vibration data measured by attaching sensors are invalid owing to surrounding problems. Therefore, in this study, vibration data on the periphery of a pump according to the pump driving force was confirmed using a two-way fluid structure interaction analysis. To this end, a case run was conducted within a changeable design range, and an efficient design for vibration reduction was suggested by comparing the data with a change in the design factor.

Simulation and experimental investigation on vibration of a radial turbine wheel using a two-way FSI approach

When turbine blades of a radial turbocharger are subjected to an unsteady aerodynamic load excitation force, high cycle fatigue of the turbine blades will occur when the excitation force reaches a certain level. The fatigue of the radial turbine wheel is affected by both static and dynamic stresses, and high cycle fatigue occurs when the dynamic stress reaches a certain amplitude. In this study, a two-way fluid–structure interaction (FSI) analysis method was used to predict the dynamic excitation force and dynamic response of the turbine wheel, which can precisely predict the forced vibration of the turbine wheel under the condition of rotor–stator interaction. A resonance intersection point was excited by the stator (turbine housing vortex tongue) of the radial turbocharger as the operating boundary condition, and the aerodynamic excitation caused by the rotor–stator interaction and the vibration amplitude of the turbine blade was predicted and analysed. A turbine blade dynamic measurement system (tip timing) was used to measure the dynamic deformation of turbine blades for turbochargers in real time. The simulation and measurement results showed that the errors of the predicted vibration displacements and measured mistuning blades were within the acceptable range, and the two-way FSI analysis method can precisely predict the forced vibration of the model.

Two-way Fluid Structure Interaction Analysis of Single Pad Externally Adjustable Fluid Film Bearing

Two-way Fluid Structure Interaction Analysis of Single Pad Externally Adjustable Fluid Film Bearing

A Coupled Two-Way Fluid–Structure Interaction Analysis for the Dynamics of a Partially Confined Cantilevered Pipe Under Simultaneous Internal and External Axial Flow in Opposite Directions

Abstract This paper presents the results of a coupled two-way fluid–structure interaction (FSI) analysis of a slender flexible vertical cantilevered pipe hanging concentrically within a shorter rigid tube forming an annulus. The pipe is subjected to internal and annular flows simultaneously. This system has applications in brine production and salt-cavern hydrocarbon storage. In this study, the fluid–structure problem is solved with a finite volume based computational fluid dynamics (CFD) code for the fluid domain coupled to a finite element based computational solid mechanics code for the structural domain. The numerical results obtained for the free-end displacement of the central pipe versus the annular/internal flow velocity ratio Uo/Ui are presented and compared with those obtained from experiment. The capability of the numerical model to predict the onset of the experimentally observed flutter instability in the system is also examined. This study provides a better insight into the dynamics of the system.

Hydro-elastic computational analysis of a marine propeller using two-way fluid structure interaction

Marine propellers have complex geometry and their performance is determined by costly and time consuming open water experiments. Use of numerical techniques helps researchers in effective design of propellers. Several approaches are used that predicted either hydrodynamic and acoustic response or structural response. Two-way fluid-structure interaction (FSI) analysis is a very useful approach providing all three responses which helps in the design, analysis and optimization of a propeller. The objective of this paper is to predict the hydro-elastic response of a propeller using two-way FSI on a 0.2m diameter, DTMB-4119 propeller using ANSYS software. Two-way FSI analysis is carried out using system coupling approach that transfers the data between the structural and fluid solvers. The turbulence effects are captured using the large-eddy simulation (LES) model and the Ffowcs Williams Hawkings (FWH) acoustic model is used for evaluating the sound pressure level (SPL) generated by propeller. Analysis is extended to evaluate the hydro-elastic and acoustic response of the propeller after validating the hydrodynamic performance with the experimental result in the literature. The results from Two-way FSI analysis are in close agreement when compared with the one-way FSI analysis. Two-way FSI can accommodate the peak value of stress and deformation developed during the initial part of the transient solution which is important in the design of propeller. This study reveals that metallic (NAB) propeller can be replaced by a composite propeller. The acoustic response from two-way FSI analysis will be more realistic due to the consideration of hydro-elastic effect of propeller.

Fluid-Structure Interaction Modelling of a Soft Pneumatic Actuator

This paper presents a fully coupled fluid-structure interaction (FSI) simulation model of a soft pneumatic actuator (SPA). Previous research on modelling and simulation of SPAs mostly involves finite element modelling (FEM), in which the fluid pressure is considered as pressure load uniformly acting on the internal walls of the actuator. However, FEM modelling does not capture the physics of the fluid flow inside an SPA. An accurate modelling of the physical behaviour of an SPA requires a two-way FSI analysis that captures and transfers information from fluid to solid and vice versa. Furthermore, the investigation of the fluid flow inside the flow channels and chambers of the actuator are vital for an understanding of the fluid energy distribution and the prediction of the actuator performance. The FSI modelling is implemented on a typical SPA and the flow behaviour inside the actuator is presented. Moreover, the bending behaviour of the SPA from the FSI simulation results is compared with a corresponding FEM simulation.

Numerical Validation of the Two-Way Fluid-Structure Interaction Method for Non-Linear Structural Analysis under Fire Conditions

Fire accidents on ships and offshore structures lead to complex non-linear material and geometric behavior, which can cause structural collapse. This not only results in significant casualties, but also environmental catastrophes such as oil spills. Thus, for the fire safety design of structures, precise prediction of the structural response to fire using numerical and/or experimental methods is essential. This study aimed to validate the two-way fluid-structure interaction (FSI) method for predicting the non-linear structural response of H-beams to a propane burner fire by comparison with experimental results. To determine the interaction between a fire simulation and structural analysis, the Fire-Thermomechanical Interface model was introduced. The Fire Dynamics Simulator and ANSYS Parametric Design Language were used for computational fluid dynamics and the finite element method, respectively. This study validated the two-way FSI method for precisely predicting the non-linear structural response of H-beams to a propane burner fire and proposed the proper time increment for two-way FSI analysis.

Comparison between an uncoupled one-way and two-way fluid structure interaction simulation on a super-tall slender structure

This paper presents a comprehensive analysis on a super-tall structure where a numerical approach is used to measure its structural response when subjected to turbulent wind. The aim of this study is to provide a feasible alternate approach, to the experimental multi-degree of freedom (MDOF) aeroelastic wind tunnel tests, which are commonly used in industry to estimate structural responses of super-tall structures. An innovative and time-efficient uncoupled one-way Fluid-Structure Interaction (FSI) simulation technique was used to measure the structural response. This novel method was evaluated against a commercially available two-way FSI analysis technique and validated with an experimental MDOF aeroelastic model. It is shown that the uncoupled one-way FSI analysis is capable of estimating structural responses and provides similar numerical accuracy to that of the experimental response. This performance was achieved in a total of 74clock hours which accounts for the CFD simulation and transient structural analysis calculated for eighteen different structural configurations. In comparison, the two-way FSI analysis, which uses a commercial code, took 4800clock hours to calculate for six configurations. The uncoupled one-way FSI technique also provided good correlations with experimentally observed trends such as vortex-induced resonance. In comparison the two-way FSI simulation was not as accurate due to the practical limitations (such as mesh size) that needed to be introduced in order to obtain results within a feasible time frame. Finally through validation, it is demonstrated that the proposed uncoupled one-way FSI analysis technique can provide accurate results at a feasible cost.

Shape Optimization for a Single Valve Vacuum Chuck Using Two-Way FSI Analysis

This study aims to optimize the inner shape of a single valve vacuum chuck to prevent flexible film from wrinkling and shorten the inspect time. Hence, this study developed a two-way fluid–structure interaction (FSI) analysis between the film and its surrounding airflow to simulate film adsorption in a porous ceramic on a single vacuum chuck. Next, the team optimized airflow velocity for the film to achieve the quickest adsorption of the porous ceramic sample in the shortest time. Finally, the vacuum chuck shape was optimized using the optimum airflow velocity profile. The Darcy–Forchheimer and Mooney–Rivlin equations were simulated to calculate the airflow through the porous ceramic and the hyper-elastic material, respectively. The B-spline curve was used to optimize the inner shape of the vacuum chuck. Adsorption tests of single- and multiple-valve vacuum chucks with optimized internal shapes were performed to verify the validity of the simulation results and compare the performance. The optimized vacuum chuck prevented film wrinkling, and the inspection time was reduced by 66% compared to the conventional multiple-valve vacuum chuck. The error between the simulation and the experimental results was within 2.5%. The techniques of the developed two-way FSI analysis and the vacuum chuck shape optimization will greatly contribute to the display and semiconductor industries.

Stiffness Adjustment of Surface-Piercing Hydrofoils Within Fluid-Structure Interaction

This paper presents results from numerical analysis of the fluid and structure interaction of two different hydrofoil models, Model 1 and Model 2. Analyzes were performed with stainless steel, aluminium and composite materials for Model 1, and Model 2 was created from composite with aluminium reinforcement. Models were analyzed for three different angles of attack (10, 20, 30 degrees) and for each angle three different speeds were tested (2, 4, 6 m/s). At first, the whole set of analysis was run for entirely submerged hydrofoils and later on for immersed hydrofoils to the draft h. Described numerical analysis was performed in order to adjust stiffens of hydrofoils based on different operational loads. Two-way fluid-structure interaction analysis was used which combines FEM and CFD solvers. Presented results are based on 44 analysis with which all planned conditions of hydrofoil operation were tested. Numerical analysis showed a correlation between stiffens of material i.e. structural response and hydrodynamic loading. Besides mentioned, based on analysis of Model 2 future prediction are given in a way of hydrofoil design or particularly placement for hydrofoils reinforcement.

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.

Fluid-Structure Interaction Analysis and the Detection of Wind Induced Vibration of Triangular Lamella

The use of very thin, subtle and light structures as an external part of buildings causes many problems related to wind induced vibration. Constructions of this type occur mostly as a part of roofs or design facades. The principal idea of this paper is to show dynamic response of triangular lamella exposed to wind gusts, which frequency is equal to the first natural frequency of the lamella. By the two-way software fluid-structure interaction (FSI) analysis, oscillation of the lamella was detected. The solution of two-way FSI analysis requires co-simulation between computational fluid dynamics and structural mechanics. In the simulation, it was essential to simulate conditions that if met, create resonant vibration of the lamella caused by vortex shedding on the leeward side of the structure. If the frequency of vortex shedding matches the resonance frequency of the structure, the structure begins to resonate and vibrates in harmonic oscillations driven by the energy of the flow. In this case, vibration rises and structure can be damaged or deformed permanently. For the long-term vibration, fatigue stress and subsequently fatigue failure is significant. By the usage of empirically derived equations, input data for the software simulation were obtained. It was important to consider mainly natural frequency of lamella, frequency of vortex shedding behind the structure and also correct properties of air such as wind speed, frequency of wind gusts, density of an air and Strouhal number. As a conclusion, dynamic response of lamella in the form of deformation and wind stream pattern depending on time is shown. It has been also shown that if the inputs are specified correctly to software simulation it is possible to analyse time history of many variables such as deformation, wind speed, and acceleration. By this method, it is possible to determine not only the maximum variables such as deformation or wind speed, but also its entire time history. In practice, it is therefore possible to create different design situations and, on their basis, design the lightweight non-bearing structures exposed to the wind.

Effectiveness of using pipe-in-pipe (PIP) concept to reduce vortex-induced vibrations (VIV): Three-dimensional two-way FSI analysis

Pipe-in-pipe (PIP) systems have been increasingly used in offshore applications because of their favourable thermal insulation capacity. Very recently, the conventional PIP system was slightly revised by using carefully designed springs and dashpots to connect the inner and outer pipes. This revised PIP system can be considered as a structure-Tuned Mass Damper (TMD) system. It therefore has the potential to mitigate the offshore structural vibrations induced by various sources such as earthquake excitation and/or vortex shedding. This paper carries out three-dimensional (3D) numerical simulations to investigate the effectiveness of the proposed method. The cross-flow oscillation of the conventional and optimized PIP systems are numerically investigated by developing a two-way coupled Fluid-Structure Interaction (FSI) framework for computational fluid dynamics (CFD) analysis. The developed FSI model is validated with the available experimental and numerical benchmark data on a single cylinder. This validated model is then extended to the PIP system to study its efficiency for Vortex-Induced Vibration (VIV) suppression. Numerical results show that the optimized PIP system can noticeably reduce VIV.

Impact of Fluid–Structure Interaction on Direct Tumor-Targeting in a Representative Hepatic Artery System

Direct targeting of solid tumors with chemotherapeutic drugs and/or radioactive microspheres can be a treatment option which minimizes side-effects and reduces cost. Briefly, computational analysis generates particle release maps (PRMs) which visually link upstream particle injection regions in the main artery with associated exit branches, some connected to tumors. The overall goal is to compute patient-specific PRMs realistically, accurately, and cost-effectively, which determines the suitable radial placement of a micro-catheter for optimal particle injection. Focusing in this paper on new steps towards realism and accuracy, the impact of fluid-structure interaction on direct drug-targeting is evaluated, using a representative hepatic artery system with liver tumor as a test bed. Specifically, the effect of arterial wall motion was demonstrated by modeling a two-way fluid-structure interaction analysis with Lagrangian particle tracking in the bifurcating arterial system. Clearly, rapid computational evaluation of optimal catheter location for tumor-targeting in a clinical application is very important. Hence, rigid-wall cases were also compared to the flexible scenario to establish whether PRMs generated when based on simplifying assumptions could provide adequate guidance towards ideal catheter placement. It was found that the best rigid (i.e., time-averaged) geometry is the physiological one that occurs during the diastolic targeting interval.

Compliant model of a coupled sequential coronary arterial bypass graft: Effects of vessel wall elasticity and non-Newtonian rheology on blood flow regime and hemodynamic parameters distribution

We have recently developed a novel design for coronary arterial bypass surgical grafting, consisting of coupled sequential side-to-side and end-to-side anastomoses. This design has been shown to have beneficial blood flow patterns and wall shear stress distributions which may improve the patency of the CABG, as compared to the conventional end-to-side anastomosis. In our preliminary computational simulation of blood flow of this coupled sequential anastomoses design, the graft and the artery were adopted to be rigid vessels and the blood was assumed to be a Newtonian fluid. Therefore, the present study has been carried out in order to (i) investigate the effects of wall compliance and non-Newtonian rheology on the local flow field and hemodynamic parameters distribution, and (ii) verify the advantages of the CABG coupled sequential anastomoses design over the conventional end-to-side configuration in a more realistic bio-mechanical condition.For this purpose, a two-way fluid–structure interaction analysis has been carried out. A finite volume method is applied to solve the three-dimensional, time-dependent, laminar flow of the incompressible, non-Newtonian fluid; the vessel wall is modeled as a linearly elastic, geometrically non-linear shell structure. In an iteratively coupled approach the transient shell equations and the governing fluid equations are solved numerically.The simulation results indicate a diameter variation ratio of up to 4% and 5% in the graft and the coronary artery, respectively. The velocity patterns and qualitative distribution of wall shear stress parameters in the distensible model do not change significantly compared to the rigid-wall model, despite quite large side-wall deformations in the anastomotic regions. However, less flow separation and reversed flow is observed in the distensible models. The wall compliance reduces the time-averaged wall shear stress up to 32% (on the heel of the conventional end-to-side model) and somewhat increases the oscillatory nature of the flow. It is found that the effects of wall compliance and non-Newtonian rheology are not independent, and they interact with each other. In spite of the modest influence of wall compliance and non-Newtonian rheology on the hemodynamic parameters distribution, the inclusion of these properties has unveiled further advantages of the coupled sequential anastomoses model over the conventional end-to-side anastomosis which had not been revealed in the previous study with the rigid-wall and Newtonian fluid models. Hence, the inclusion of wall compliance and non-Newtonian rheology in flow simulation of blood vessels can be essential in quantitative and comparative investigations.

Investigation of the Hemodynamic Effect of Stent Wires on Renal Arteries in Patients with Abdominal Aortic Aneurysms Treated with Suprarenal Stent-Grafts

The purpose of the study was to investigate the hemodynamic effect of stent struts (wires) on renal arteries in patients with abdominal aortic aneurysms (AAAs) treated with suprarenal stent-grafts. Two sample patients with AAA undergoing multislice CT angiography pre- and postsuprarenal fixation of stent-grafts were selected for inclusion in the study. Eight juxtarenal models focusing on the renal arteries were generated from the multislice CT datasets. Four types of configurations of stent wires crossing the renal artery ostium were simulated in the segmented aorta models: a single wire crossing centrally, a single wire crossing peripherally, a V-shaped wire crossing centrally, and multiple wires crossing peripherally. The blood flow pattern, flow velocity, wall pressure, and wall shear stress at the renal arteries pre- and post-stent-grafting were analyzed and compared using a two-way fluid structure interaction analysis. The stent wire thickness was simulated with a diameter of 0.4, 1.0, and 2.0 mm, and hemodynamic analysis was performed at different cardiac cycles. The interference of stent wires with renal blood flow was mainly determined by the thickness of stent wires and the type of configuration of stent wires crossing the renal ostium. The flow velocity was reduced by 20-30% in most of the situations when the stent wire thickness increased to 1.0 and 2.0 mm. Of the four types of configuration, the single wire crossing centrally resulted in the highest reduction of flow velocity, ranging from 21% to 28.9% among three different wire thicknesses. Wall shear stress was also dependent on the wire thickness, which decreased significantly when the wire thickness reached 1.0 and 2.0 mm. In conclusion, our preliminary study showed that the hemodynamic effect of suprarenal stent wires in patients with AAA treated with suprarenal stent-grafts was determined by the thickness of suprarenal stent wires. Research findings in our study are useful for follow-up of patients treated with suprarenal stent-grafts to ensure long-term safety of the suprarenal fixation.