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Shape Gradient Methods for Shape Optimization of an Unsteady Multiscale fluid-structure interaction Model

JOURNAL OF GEOMETRIC ANALYSIS 2024年第8期34卷 245-245页

作者： Zhang, Keyang Zhu, Shengfeng Li, Jiajie Yan, Wenjing East China Normal Univ Sch Math Sci Shanghai 200241 Peoples R China East China Normal Univ Key Lab MEA Minist Educ Shanghai 200241 Peoples R China East China Normal Univ Shanghai Key Lab PMMP Shanghai 200241 Peoples R China Shanghai Jiao Tong Univ Sch Math Sci Shanghai 200240 Peoples R China Xi An Jiao Tong Univ Sch Math & Stat Xian 710049 Shaanxi Peoples R China

We consider numerical shape optimization of a fluid-structure interaction model. The constrained system involves multiscale coupling of a two-dimensional unsteady Navier-Stokes equation and a one-dimensional ordinary differential equation for fluid flows and structure, respectively. We derive shape gradients for both objective functionals of least-squares type and energy dissipation. The state and adjoint state equations are numerically solved on the time-dependent domains using the Arbitrary-Lagrangian-Eulerian method. Numerical results are presented to illustrate effectiveness of algorithms.

关键词： Shape optimization fluid-structure interaction Finite element method Shape gradient

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Porcine and bovine aortic valve comparison for surgical optimization: A fluid-structure interaction modeling study

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INTERNATIONAL JOURNAL OF CARDIOLOGY 2021年 334卷 88-95页

作者： Li, Caili Tang, Dalin Yao, Jing Shao, Yongfeng Sun, Haoliang Hammer, Peter Gong, Chanjuan Ma, Luyao Zhang, Yanjuan Wang, Liang Yu, Han Yang, Chun Baird, Christopher Southeast Univ Sch Math Nanjing Peoples R China Southeast Univ Sch Biol Sci & Med Engn Nanjing Peoples R China Worcester Polytech Inst Dept Math Sci Worcester MA 01609 USA Nanjing Med Univ Affiliated Hosp 1 Dept Cardiol Nanjing Peoples R China Nanjing Med Univ Affiliated Hosp 1 Dept Cardiovasc Surg Nanjing Peoples R China Harvard Med Sch Boston Childrens Hosp Dept Cardiac Surg Boston MA 02115 USA Nanjing Med Univ Affiliated Hosp 1 Dept Anesthesiol Nanjing Peoples R China China Informat Tech Designing & Consulting Inst C Beijing Peoples R China Southeast Univ Nanjing Peoples R China

Background: Porcine aortic valve (PAV) and bovine aortic valve (BAV) are commonly used in aortic valve replacement (AVR) surgeries. A detailed comparison for their hemodynamic and structural stress/strain performances would help to better understand valve cardiac function and select valve type and size for AVR outcome optimizations. Methods: Eight fluid-structure interaction models were constructed to compare hemodynamic and stress/strain behaviors of PAV and BAV with 4 sizes (19, 21, 23, and 25 mm). Blood flow velocity, systolic cross-valve pressure gradient (SCVPG), geometric orifice area (GOA), flow shear stresses (FSS), and stress/strain were obtained for comparison. Results: Compared with PAV, BAV has better hemodynamic performance, with lower maximum flow velocity (7.17%) and pressure (9.82%), smaller pressure gradient (mean and peak SCVPG: 8.92% and 9.28%), larger GOA (9.56%) and lower FSS (6.61%). The averages of the mean and peak net pressure gradient values from 4 BAV models were 8.10% and 8.35% lower than that from PAV models. Larger valve sizes for both PAV and BAV had improved hemodynamic performance. Maximum flow velocity, pressure, mean SCVPG and maximum FSS from 25 mm BAV were 36.80%, 15.81%, 39.05% and 38.83% lower than those from 19 mm BAV. The GOA of PAV and BAV 25 mm Valve were 43.75% and 33.07% larger than 19 mm valves, respectively. BAV has lower stress on the leaflets than PAV. Conclusions: BAV had better hemodynamic performance and lower leaflets stress than PAV. More patient studies are needed to validate our findings. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http:// ***/licenses/by/4.0/).

关键词： Aortic valve replacement fluid-structure interaction Porcine aortic valve Bovine aortic valve

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Modeling of soft fluidic actuators using fluid-structure interaction simulations with underwater applications

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INTERNATIONAL JOURNAL OF MECHANICAL SCIENCES 2023年 255卷

作者： Xavier, Matheus S. Harrison, Simon M. Howard, David Yong, Yuen K. Fleming, Andrew J. Univ Melbourne Dept Elect & Elect Engn Parkville Vic 3010 Australia Data61 CSIRO Clayton Vic 3168 Australia Data61 CSIRO Pullenvale Qld 4069 Australia Univ Newcastle Sch Engn Precis Mechatron Lab Callaghan NSW 2308 Australia

Soft robots have been developed for a variety of applications including gripping, locomotion, wearables and medical devices. For the majority of soft robots, actuation is performed using pneumatics or hydraulics. Many previous works have addressed the modeling of these fluid-driven soft robots using static finite element simulations where the pressure inside the actuator is assumed to be constant and uniform. The assumption of constant internal pressure is a useful simplification but introduces significant errors during events such as pressurization, depressurization, and transient loads from a liquid environment. Applications that use soft actuators for locomotion or propulsion operate using a sequence of transient events, so accurate simulation of these events is critical to optimizing performance. To improve the simulation of soft fluidic actuators and enable the modeling of both internal and external fluid flow in underwater applications, this work describes a fully-coupled, three-dimensional fluid-structure interaction simulation approach, where the pressure and flow dynamics are explicitly solved. This approach provides a realistic simulation of soft actuators in fluid environments, and permits the optimization of transient responses, which may be due to a combination of environmental fluid loads and non-uniform pressurization. The proposed methods are demonstrated in a number of case studies and experiments for a range of actuation and both internal and external inlet flow configurations, including bending actuators, a soft robotic fish fin for propulsion, and experimental results of a bending actuator in a high-speed fluid, which correlate closely with simulations. The proposed approach is expected to assist in the design, modeling, and optimization of bioinspired soft robots in underwater applications.

关键词： Soft robotics Soft actuators fluid-structure interaction Finite element modeling Underwater robots

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Effect of aortic bifurcation geometry on pressure and peak wall stress in abdominal aorta: fluid-structure interaction study

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MEDICAL ENGINEERING & PHYSICS 2023年第1期118卷 104014-104014页

作者： Jagos, Jiri Schwarz, David Polzer, Stanislav Bursa, Jiri Brno Univ Technol Fac Mech Engn Tech 2896-2 Brno 61669 Czech Republic VSB Tech Univ Ostrava Dept Appl Mech 17 listopadu 2172-15 Ostrava 70800 Czech Republic

Background and Objective: Geometry of aorto-iliac bifurcation may affect pressure and wall stress in aorta and thus potentially serve as a predictor of abdominal aortic aneurysm (AAA), similarly to ***: Effect of aorto-iliac bifurcation geometry was investigated via parametric analysis based on two-way weakly coupled fluid-structure interaction simulations. The arterial wall was modelled as isotropic hyperelastic monolayer, and non-Newtonian behaviour was introduced for the fluid. Realistic boundary conditions of the pulsatile blood flow were used on the basis of experiments in literature and their time shift was tailored to the pulse wave velocity in the model to obtain physiological wave shapes. Eighteen idealized and one patient-specific geometries of human aortic tree with common iliac and renal arteries were considered with different angles between abdominal aorta (AA) and both iliac arteries and different area ratios (AR) of iliac and aortic luminal cross ***: Peak wall stress (PWS) and systolic blood pressure (SBP) were insensitive to the aorto-iliac angles but sensitive to the AR: when AR decreased by 50%, the PWS and SBP increased by up to 18.4% and 18.8%, ***: Lower AR (as a result of the iliac stenosis or aging), rather than the aorto-iliac angles increases the BP in the AA and may be thus a risk factor for the AAA development.

关键词： Aortic bifurcation fluid-structure interaction Abdominal aortic aneurysm Atherosclerosis Aorto-iliac ratio Aorto-iliac angles

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Effect of TAVR commissural alignment on coronary flow: A fluid-structure interaction analysis

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COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2023年 242卷 107818-107818页

作者： Oks, David Houzeaux, Guillaume Vazquez, Mariano Neidlin, Michael Samaniego, Cristobal Barcelona Supercomp Ctr Comp Applicat Sci & Engn Placa Eusebi Guell 1-3 Barcelona 08034 Spain ELEM Biotech SL Placa Pau Vila1 Bloc APlanta 3Porta 3A1 Barcelona 08003 Spain Rhein Westfal TH Aachen Med Fac Inst Appl Med Engn Dept Cardiovasc Engn Pauwelstr 20 D-52074 Aachen Germany

Background and Objectives: Coronary obstruction is a complication that may affect patients receiving Transcatheter Aortic Valve Replacement (TAVR), with catastrophic consequences and long-term negative effects. To enable healthy coronary perfusion, it is fundamental to appropriately position the device with respect to the coronary ostia. Nonetheless, most TAVR delivery systems do not control commissural alignment to do so. Moreover, no in silico study has directly assessed the effect of commissural alignment on coronary perfusion. This work aims to evaluate the effect of TAVR commissural alignment on coronary perfusion and device ***: A two-way computational fluid-structure interaction model is used to predict coronary perfusion at different commissural alignments. Moreover, in each scenario, hemodynamic biomarkers are evaluated to assess device ***: Commissural misalignment is shown to reduce the total coronary perfusion by -3.2% and the flow rate to a single coronary branch by -6.8%. It is also observed to impair valvular function by reducing the systolic geometric orifice area by -2.5% and increasing the systolic transvalvular pressure gradients by +5.3% and the diastolic leaflet stresses by +16.0%.Conclusions: The present TAVR patient model indicates that coronary perfusion, hemodynamic and structural performance are minimized when the prosthesis commissures are fully misaligned with the native ones. These results support the importance of enabling axial control in new TAVR delivery catheter systems and defining recommended values of commissural alignment in upcoming clinical treatment guidelines.

关键词： TAVR Coronary flow fluid-structure interaction In silico High-performance computing Hemodynamics

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Neural-network-based fluid-structure interaction applied to vortex-induced vibration

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JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS 2023年 428卷

作者： Bublik, Ondrej Heidler, Vaclav Pecka, Ales Vimmr, Jan Univ West Bohemia Fac Appl Sci NTIS New Technol Informat Soc Tech 8 Plzen 30100 Czech Republic Univ West Bohemia Fac Appl Sci Dept Mech Tech 8 Plzen 30100 Czech Republic

In this paper, a fluid-structure interaction (FSI) solver with neural-network-based fluid -flow prediction is proposed. This concept is applied to the problem of vortex-induced vibration of a cylinder. The majority of studies that are concerned with fluid-flow prediction using neural networks solve problems with fixed boundary. In this paper, a convolutional neural network (CNN) is used to predict unsteady incompressible laminar flow with moving boundary. A deformable non-Cartesian grid, which traces the boundary of the fluid domain, is used in this paper. The CNN is trained for oscillating cylinder with various frequencies and amplitudes. The dynamics of the elastically -mounted cylinder is modelled using a linear spring-mass-damper model and solved by an implicit differential scheme. The results show that the CNN-based FSI solver is capable of capturing the so-called lock-in phenomenon for the problem of vortex -induced vibration of a cylinder and the quantitative behaviour is similar to the results of the CFD-based FSI solver. Moreover, the CNN-based FSI solver is two orders of magnitude faster than the CFD-based FSI solver and the speedup is expected to be even greater on larger problems. (c) 2023 Elsevier B.V. All rights reserved.

关键词： Convolution neural network Unsteady fluid flow Vortex -induced vibration fluid-structure interaction

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Study on fluid-structure interaction characteristics for coaxial cylindrical shells with liquid in the annular gap

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ANNALS OF NUCLEAR ENERGY 2023年 182卷

作者： Li, Donghao Lu, Daogang Zhu, Yuxuan Liu, Yu Zhang, Chaofan Duan, Dexuan North China Elect Power Univ Sch Nucl Sci & Engn Beijing 102206 Peoples R China Beijing Key Lab Pass Safety Technol Nucl Energy Beijing 102206 Peoples R China

There are many coaxial cylindrical thin-wall structures with narrow fluid gaps in the reactor vessel of the pooltype fast reactor. The fluid-structure interaction characteristics of such structures are important for the reactor's safety in an earthquake. However, the fluid-structure interaction characteristics of coaxial cylindrical shells with different boundary conditions and the inner-outer-shell coupling remains to be explored. In this paper, we study the added mass for the shell-type vibration of single-end-fixed coaxial cylindrical shells by vibration experiments and the finite element method (FEM). Then, we study the influence of the outer shell's rigidity and different boundary conditions (single-end-fixed and double-end-fixed cylinder) on the modal frequency and the added mass by the FEM. It shows that different boundary conditions cause a 50% difference in the added mass with modes with small circumferential wave numbers. This work provides a benchmark for strong fluid-structure interaction for flexible double shells with small fluid gaps.

关键词： fluid-structure interaction Added mass Vibration experiments Coaxial thin-wall shell Shell model

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Thermo-Mechanical fluid-structure interaction Numerical Modelling and Experimental Validation of MEMS Electrothermal Actuators for Aqueous Biomedical Applications

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MICROMACHINES 2023年第6期14卷 1264-1264页

作者： Sciberras, Thomas Demicoli, Marija Grech, Ivan Mallia, Bertram Mollicone, Pierluigi Sammut, Nicholas Univ Malta Fac Engn Dept Mech Engn Msida MSD 2080 Malta Univ Malta Inst Sustainable Energy Marsaxlokk MXK 1531 Malta Univ Malta Fac Informat & Commun Technol Dept Microelect & Nanoelect Msida MSD 2080 Malta Univ Malta Fac Engn Dept Met & Mat Engn Msida MSD 2080 Malta

Recent developments in MEMS technologies have made such devices attractive for use in applications that involve precision engineering and scalability. In the biomedical industry, MEMS devices have gained popularity in recent years for use as single-cell manipulation and characterisation tools. A niche application is the mechanical characterisation of single human red blood cells, which may exhibit certain pathological conditions that impart biomarkers of quantifiable magnitude that are potentially detectable via MEMS devices. Such applications come with stringent thermal and structural specifications wherein the potential device candidates must be able to function with no exceptions. This work presents a state-of-the-art numerical modelling methodology that is capable of accurately predicting MEMS device performance in various media, including aqueous ones. The method is strongly coupled in nature, whereby thermal as well as structural degrees of freedom are transferred to and from finite element and finite volume solvers at every iteration. This method therefore provides MEMS design engineers with a reliable tool that can be used in design and development stages and helps to avoid total reliability on experimental testing. The proposed numerical model is validated via a series of physical experiments. Four MEMS electrothermal actuators with cascaded V-shaped drivers are presented. With the use of the newly proposed numerical model as well as the experimental testing, the MEMS devices' suitability for biomedical applications is confirmed.

关键词： numerical modelling electrothermal actuator (ETA) V-shaped driver microelectromechanical system (MEMS) fluid-structure interaction finite element finite volume submerged underwater aqueous

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The fluid-structure interaction lubrication performances of a novel bearing: Experimental and numerical study

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TRIBOLOGY INTERNATIONAL 2023年 179卷

作者： Xie, Zhongliang Jiao, Jian Wrona, Stanislaw Northwestern Polytech Univ Dept Engn Mech Xian 710072 Peoples R China Northwestern Polytech Univ Shenzhen Res & Dev Inst Shenzhen 518057 Peoples R China Xidian Univ Sch Mech Elect Engn Xian 710071 Peoples R China Silesian Tech Univ Dept Measurements & Control Syst Gliwice Poland Northwestern Polytech Univ Dept Engn Mech Xian 710072 Peoples R China

This paper proposes a novel double-liner bearing in order to overcome the disadvantages of traditional water -lubricated single-liner bearings. It is expected to achieve a new breakthrough in the performances of high -load, low-resistance, vibration-attenuation and noise-reduction. The fluid-structure interaction dynamic model of sandwich liner bearing is established. Turbulent effect is taken into account. The influences of eccentricity ratios and liner thickness on the lubrication performance are studied. The evolution mechanisms of liner thickness on lubrication performances are revealed. The results show that there are superior lubrication be-haviors in sandwich liner bearing. The present study enriches the theoretical systems of the lubrication. It provides new ideas and ways for the design and R&D of the bearing, which is of great significance.

关键词： Water-lubricated bearing fluid-structure interaction Nonlinear dynamic behaviors Sandwich-liner

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A fluid-structure interaction Tool Using a Van der Pol-Based Reduced-Order Model for Buffet and Nonsynchronous Vibrations

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JOURNAL OF TURBOMACHINERY-TRANSACTIONS OF THE ASME 2023年第1期145卷 011009-011009页

作者： Hollenbach, Richard Kielb, Robert Hall, Kenneth Duke Univ Pratt Sch Engn Thomas Lord Dept Mech Engn Durham NC 27703 USA Duke Univ Pratt Sch Engn Thomas Lord Dept Mech Engn Durham NC 27708 USA

This paper builds upon a two-degree-of-freedom Van der Pol oscillator-based reduced-order model for studying the mechanisms around nonsynchronous vibrations (NSV) in turbomachinery. One degree tracks the fluid motion utilizing a combination of a traditional Van der Pol oscillator and a Duffing oscillator;the other degree of freedom is a mass on a spring and a damper, in this case, a cylinder. Thus, this model can be considered one of fluid-structure interaction. The cubic stiffening from the Duffing oscillator proved to improve the match to experimental data. Using this model to study the time history of the fluid and the structure oscillation, additional parameters are extracted to understand the underlying mechanisms of frequency lock-in and limit cycle oscillation. First, the phase shift between the vortex shedding and the structural motion is calculated when it locks-in and then unlocks. Second, the work done per cycle is analyzed from the contributions of the mass, spring, and damping forces to determine the dominant contributor when locking-in versus unlocking. Third, the phase portrait is plotted on a Poincare map to further study the locked-in versus unlocked responses. This model is then validated against not only experimental data but also computational simulation results and previous reduced-order models. The finalized model can now serve as a preliminary design tool for turbomachinery applications. For more realistic and accurate modeling, the third degree of freedom in the form of an airfoil pitching motion will be added in a separate paper as well.

关键词： nonsynchronous vibrations Van der Pol fluid-structure interaction reduced order model computational fluid dynamics (CFD) fan compressor turbine aerodynamic design

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