FSI Method Research Articles

Numerical Simulations of 122 mm M-21OF Missile Fragments Propulsion

This paper presents numerical simulations of 122 mm M-21OF rocket fragments propulsion. A simplified geometry of the rocket was constructed and analysed with two main numerical FE approaches: a mesh-based lagrangian-eulerian FSI method and a coupled meshless SPH–lagrangian approach. The resulting fragment velocities were compared with those obtained from an analytical approach (Gurney formula). The shell fragmentation process was also successfully depicted. Both numerical approaches differed from the analytical velocity results to a comparable degree. Considering that the Gurney energy of a high-explosive is obtained from cylinder expansion tests, results obtained with the Gurney method can be treated as a reference point and validation method for natural fragmentation warhead models.

Analysis of fluid-structure interaction in diaphragm plug valves for filling electrolyte in lithium-ion battery cells

In this paper, the stress and the local liquid residue of the diaphragm plug valve were simulated. Simulation of the diaphragm plug valve opening process was performed by using a bidirectional fluid-structure interaction based on dynamic mesh technique. The pressure and velocity distribution of the internal flow were obtained with boundary conditions for the fluid–structure interaction during the opening process. The finite element method was used to compare the equivalent stress with FSI method. The results indicate that mechanical tensile stress plays a prominent role in determining the equivalent stress of the diaphragm, with the highest stress concentration occurring in the root region. The electrolyte flow in the valve tends to be stable when reaching an opening degree of 56.6 %. Crystallization accumulation will occur due to the existence of vortices in the flow field around the diaphragm which affects the fluidity of the fluid, this area needs to be focused on.

Impact of palatopharyngeal sizes changing on pharyngeal airflow fluctuation and airway vibration in a pediatric airway

Snoring is common in children and is associated with many adverse consequences. One must study the relationships between pharyngeal morphology and snoring physics to understand snoring progression. Although some model studies have provided fluid–structure interaction dynamic descriptions for the correlation between airway size and snoring physics, the descriptions still need to be further investigated in patient-specific airway models. Fluid-structure interaction studies using patient-specific airway structures complement the above model studies. Based on reported cephalometric measurement methods, this study quantified and preset the size of the palatopharynx airway in a patient-specific airway and investigated how the palatopharynx size affects the pharyngeal airflow fluctuation, soft palate vibration, and glossopharynx vibration with the help of a verified FSI method. The results showed that the stenosis anterior airway of the soft palate increased airway resistance and airway resistance fluctuations, which can lead to increased sleep effort and frequent snoring. Widening of the anterior airway can reduce airflow resistance and avoid obstructing the anterior airway by the soft palate vibration. The pharyngeal airflow resistance, mouth inflow proportion, and soft palate apex displacement have components at the same frequencies in all airway models, and the glossopharynx vibration and instantaneous inflow rate have components at the same frequencies, too. The mechanism of this same frequency fluctuation phenomenon can be explained by the fluid–structure interaction dynamics of an ideal coupled model consisting of a flexible plate model and a collapsible tube model. The results of this study demonstrate the potential of FSI in studying snoring physics and clarify to some degree the mechanism of airway morphology affecting airway vibration physics.

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.

Would FSI Method Will Give More Details About AAA Rupture?

Would FSI Method Will Give More Details About AAA Rupture?

Investigation of the Effect of Hot Fluid on Deformation in T-Shaped Pipes by FSI Method Using Different Material

In this study, the high-temperature liquid water flow through the cross-section of a T pipe and the effect of the temperature of the liquid on the pipe material has been investigated. Pipe deformation caused by fluid temperature has been analyzed by the Fluid-structure interaction method. The effect of temperature distribution inside the pipe has been considered as thermal load in the structural analysis of the pipe body. The finite volume method has been used in the study with numerical methods. While k-ε is preferred as the turbulence model, the mesh file created to be used in the analysis contains 200,000 grid cells. For all calculations, the Reynolds number has been set to 3900 and kept constant. The geometry of the T pipe, the fluid passing through the pipe and used the boundary have been constant for the numerical analysis made in the study. The pipe material has been determined as the only parameter that changed. As different pipe materials magnesium, aluminum, copper, steel, concrete, cast iron, and titanium have been used. As a result of the study, thermal strain, total deformation, and directional deformation values have been determined. As a result, it has been determined that the greatest deformation under thermal load is in magnesium pipes, and the smallest deformation is in titanium pipes. It has been observed that the total amount of deformation of the pipe made of magnesium is three times higher than that of the titanium pipe.

Dynamic Response of Outer Windshield Structure in Different Schemes under Aerodynamic Load

With the increase in high-speed train (HST) operation speed, the light-weight design of the train body and component structure is pursued to reduce energy consumption during operation, but this seriously deteriorates the aerodynamic performance of the light-weight structure outside the train body under the effect of strong unsteady airflow, and the more obvious case is the frequently occurring problem of vibration, large deformation, and damage to the rubber exterior windshield at the connection position of HST carriages. We investigate the fluid–structure coupling mechanism of the interaction between the rubber external windshield and aerodynamic force, and compare the dynamic characteristics of windshield structure under different design parameters. A numerical simulation of three rubber outer windshield structure parameters (sidewall distance of U-shaped capsule, sidewall thickness, sidewall inclination angle) is carried out using FSI simulation of the two-way coupling method. The aerodynamic load, airflow dynamics around the windshield, and the nonlinear vibration and deformation form of the windshield is analyzed in detail. The results show that the aerodynamic response of the HST rubber external windshield analyzed by the FSI method is in good agreement with the full-scale test results. Additionally, the stiffness of the windshield can be improved by increasing the thickness of the windshield sidewall. When the distance between the sidewall of the windshield is increased, an insufficient thickness at the top of the arc causes a large local deformation at the top of the arc of the windshield. The method established and relevant research results can provide good support for the aerodynamic stability evaluation of HST windshields.

Numerical simulation for the control rod assembly drop time evaluation in a LFR

During scram, the Control Rod Assembly (CRA) is quickly dropped into the core and as well, if any of the operating limits are exceeded, the CRA is dropped into the core within a stipulated time to shut down the reactor power as soon as possible. In this study, the Computational Fluid Dynamics (CFD) approach was used to investigate the CRA drop dynamics of a lead-based research reactor. To simulate the flow field around the CRA in the guide tube, a 3-dimensional model of the CRA in the LBE-filled guide tube was developed and discretized; and the averaged Navier-Stokes equations coupled with the dynamic mesh method were adopted. Considering the large mesh deformation in the LBE coolant domain while the CRA drops, the recently developed FSI method in the CFX code, namely the rigid body approach, was adopted, which falls under the monolithic method. In this method, the translational CRA wall, which is partially immersed in the LBE, was set as a rigid body. It has the advantage of updating and improving the mesh quality through the mesh and re-meshing technique during the process of computation. Compared with the results of the work done in the available literature, the CFD model proved to be applicable and reliable. From the results, the inherent high density among the LBE flow characteristics had the most influence on the drop time. The mass of the CRA impacts its driving force so that the drop time reduces when the CRA mass is increased. In conclusion, the method used in this study can be applied to compute and predict significant parameters which can serve as a reference for a suitable design of the CRA and its drive mechanism in the case of modification for safety.

Numerical Investigation of the Trailing Edge Shape on the Added Damping of a Kaplan Turbine Runner

Hydraulic turbine runners experience high excitation forces in their daily operations, and these excitations may cause resonances to runners, which may induce high vibrations and shorten the runner's lifetimes. Increasing the added damping of runners in water can be helpful to reduce the vibration level during resonances. Some studies have shown that the modification of the trailing edge shape can be helpful to increase added damping of hydrofoils in water. However, the influence of blade trailing edge shape on the added damping of hydraulic turbine runners has been studied in a limited way before. Due to the difficulties to study this problem experimentally, the influence of blade trailing edge shape on a Kaplan turbine runner has been studied numerically in this paper and the one-way FSI method was implemented. The performances of three different turbulence models, including the k − ϵ , k − ω SST , and transition SST models, in the added damping simulation of the NACA 0009 hydrofoil were evaluated by comparing with the available results of the two-way FSI simulation in the references. Results show that, unlike the significantly different performances in the two-way FSI method, the performances of all the turbulence models are very close in the one-way FSI method. Then, the k − ϵ turbulence model was applied to the added damping simulation of a Kaplan turbine runner, and results show that the modification of the blade trailing edge shape can be helpful to increase the added damping to some extent.

Analisis Konstruksi Pipa Pompa Suction 112-JB

The 101-JTC condenser tank has excess steam condensate due to the addition of admission steam from 101-JT. Therefore, it is necessary to design a piping system that connects 101-JTC condenser tank with the 112-JB pump to drain the condensed excess steam. The designed piping system will encounter a dynamic response caused by fluid flow fluctuation over the time. This dynamic response causes the pipe to experience stress. To find out the resulting voltage which will not cause damage or failure, it is necessary to estimate the safety factor in a piping system that has been given static and dynamic loading. This research uses the fluid structure interaction or FSI method with the help of ANSYS software as a simulation tool. The results of this study are, the flow in the pipe causes an impact load which makes the structure vibrate freely damped. The resulting dynamic response describes, the structure displacement amplitude decreases with increasing time. This indicates a stable vibration. Finally, when viewed from the value of stress against time, the fatigue that occurs in the pipe structure induce a stress below the stress limit on Goodman diagram. It can be estimated that the structure has no service life limit. The fatigue safety factor is 7.1.

An immersed boundary fluid–structure interaction method for thin, highly compliant shell structures

A parallel computational method for simulating fluid–structure interaction problems involving large, geometrically nonlinear deformations of thin shell structures is presented and validated. A compressible Navier-Stokes solver utilizing a higher-order finite difference immersed boundary method is coupled with a geometrically nonlinear computational structural dynamics solver employing the mixed interpolation of tensorial components formulation for thin triangular shell elements. A weak fluid–structure coupling strategy is used to advance the numerical solution in time. The thin shell structures are represented in the fluid domain by a geometry mesh with a finite thickness at or below the size of the local grid spacing in the fluid domain. The methodologies for load and displacement transfer between the disparate geometry and structural meshes are detailed considering a parallel computing environment. The coupled method is validated for canonical simulation-based test cases and experimental fluid–structure interaction problems considering large deformations of thin shell structures, including a shock impinging on a cantilever plate, a fixed cylinder with a flexible trailing filament in channel flow, a thin, clamped plate in wall-bounded flow, and a flag waving in viscous crossflow. The FSI method is then demonstrated on a compliant circular sheet with a clamped center exposed to crossflow and finally applied to the inflation of a spacecraft disk-gap-band parachute inflating in supersonic flow conditions resembling the upper Martian atmosphere, where comparison with experimental data is provided.

基于流固耦合方法的球形阻隔防爆材料结构受力及阻流分析

基于流固耦合方法的球形阻隔防爆材料结构受力及阻流分析

Design and Implementation of FS-I Method to Improve Effectiveness of Product Advertising using Social Media, Based on Quality Function Deployment and Fuzzy Servqual

The development of advertising, many companies use social media as an alternative online advertising. It is more interactive to promote their product. The purpose of study is to determine the comparison of strategies to improve the quality of advertising services on several social media. The results of the validity and reliability test showed that the items of questions for the questionnaire were all valid and reliable. The method used in this study is fuzzy servqual and quality function deployment. The fuzzy logic integration aims to calculate the total weight, average, and gap values of the subjectivity of the results of the servqual method. The proposed improvement in this research is based on data processing using the quality function deployment method. The main target of the proposed improvement by making the most popular company advertisements, providing up-to-date information, lots of promotions, the most interesting features, and many customer interests.

Numerical investigation on the relationship of cavitation initiation in bileaflet mechanical heart valves (BMHVs) with the aortic root geometry and valve’s implantation rotation angle

Thromboembolism remains a major concern associated with the use of BMHVs, and one of its leading causes could be cavitation, which has been reported to occur due to rapid closing of BMHV leaflets and consequent pressure drop. The aortic root geometry and the implantation rotation of BMHV significantly affect the leaflet kinematics and associated hemodynamics of BMHV and, consequently, may also initiate cavitation which has been investigated in this study. Two aortic roots, straight and bulged, were modelled, while three implantation rotation angles of BMHV were modelled, differing by 45°. ALE was employed as the FSI method, and blood was modelled as non-Newtonian. The results show that the closing velocity of one of the leaflets of a 0° rotated BMHV was 15% higher in bulged aorta as compared to straight aorta. The maximum closing velocity of fast closing leaflet was found to increase with the increasing implantation rotation of BMHV in bulged aorta, being, respectively, 8% and 19% higher for 45° and 90° rotated BMHV as compared to a 0° rotated BMHV. Consequently, it was observed that the pressure dropped below the vapour pressure for all the modelled implantation rotation angles of BMHV in bulged aorta near the leaflet tip. The maximum pressure drop across BMHV also increased with the increasing implantation rotation of BMHV in bulged aorta, being, respectively, 20% and 44% higher for 45° and 90° rotated BMHV as compared to a 0° rotated BMHV. The leaflet kinematics have been found liable to initiate cavitation.

The analysis of the dimple arrangement of the artificial hip joint to the performance of lubrication

Artificial hip joint surgery is one of the most successful methods used to restore the functioning of damaged hip bones. But there are obstacles to the use of artificial hip bone, which is the amount of friction occurring and wears. To overcome these obstacles, a surface of the artificial hip joint is modified by adding dimples in order to minimize the contact pressure of solid and to reduce friction and wear. The purpose of this study is to determine a better of lubrication performance with the variations of the dimple arrangements under the normal walking condition. Simulation results have already exited the point of convergence studies, and the obtained results are such as hydrodynamic pressure, contact pressure, and the film thickness of the lubricant with the variations of the number and pitch dimples. The results of the CSM method under dry condition, it shows that the addition of surface with dimples has a positive effect to reduce the contact pressure and indirectly reduce wear. The maximum surface contact pressure is 54.84 MPa with dimple and 94.22 MPa without a dimple. The results of the FSI method under lubrication condition, it was found that the variation of 7 dimples with a dimple pitch of 500 μm has the best lubrication performance. The hydrodynamic pressure is 0.73 Pa, the contact pressure is 0.42 Pa, and the film thickness of the lubricant is 29.59 μm. The increase of film thickness that occurs due to hydrodynamic pressure will cause the fluid lift force to withstand the loading of the solid structure.

Fluid structure interaction with a finite rate chemistry model for simulation of gaseous detonation metal-forming

Numerical simulation of metal-forming by gaseous detonation in a stoichiometric mixture of H2-O2 is performed in this paper, utilizing the Space-Time Conservation Element and Solution Element (CESE) method. We employ the CESE method to solve the reacting flow equations, including realistic finite-rate chemistry model. The detonation mechanism is considered by a detailed mechanism of the seven species and sixteen reactions for H2-O2 mixture. The fluid-structure interface treatments smoothly handle between detonation wave and work piece by using the immersed boundary method (IBM). To accurately predict the behavior of the work piece, the fluid (CESE) solver was coupled with the LS-DYNA® FEM structural solver.The fluid solver applies the fluid pressure on the structural elements as external boundary conditions and feeds back the displacements and velocity of the interface from the structural solver as its new boundary, while the chemistry solver preparing all source terms in the conservation equation for fluid solver.Our purpose is to evaluate the accuracy of CESE-IBM FSI method to handle the gaseous detonation metal-forming, which is a very complex FSI problem with chemistry. After a description of CESE-IBM FSI method, finite-rate chemistry model and experimental test set-up, a comparison is performed through the detonation characteristics, midpoint deflection of the work piece, and effect of initial pressure and temperature of the gas mixture. A good agreement is obtained between numerical results and empirical data.

유체-구조 연성 해석 기반 해저케이블 위해인자에 대한 수치 시뮬레이션에 미치는 오일러 영역 모델링의 부피와 메시 크기의 영향

The damaged subsea cable causes social and economic losses as well as high repair cost. Various types of facilities protecting the subsea cable from hazard apparatus such as anchor have been developed. Previous studies related to subsea cable protection facilities have not fully considered the actual underwater conditions. In this study, numerical analyses were carried out to simulate the underwater drop of stock anchor which is one of the biggest risk factors for subsea cable failure. The numerical simulations of the underwater drop of the stock anchor applied fluid-structure interaction analysis based on the three-dimensional coupled Euler-Lagrange method to take into account the actual underwater conditions. Since the numerical computation cost of the 3-D FSI method is very high, we evaluated the parameter influence on the Euler domain in order to realize reasonable modeling related to the simulation. The numerical simulation results were validated by comparing with the results of the theoretical solutions. The numerical simulation cost according to the parameter change was also reviewed, and reasonable Euler domain modeling parameters were determined.

Analysis of Fire Water Monitor Jet Reaction Forces and Their Influences on the Roll Stabilities of Urban Firefighting Vehicle

Urban main fire fighting vehicle is the most important item of firefighting equipment. The stability and safety of these vehicles need to be assured to avoid fire extinguishing accidents due to vehicle stability or safety problems, especially when firefighting under complex working conditions. Jet reaction force is produced by the stationary nozzle, and its direction is opposite of the jet direction. Consequently, the jet reaction force has a negative effect on the stability of the fire fighting vehicle during the firefighting process. Thus, this paper explores the relationship of jet reaction forces from a fire water monitor under different flow rate operating conditions by using finite element simulations (Fluent and Fluid-Structure Interaction simulations) and experimental research. The FSI method is proposed as a new simulation approach in this study to analyze the fire water monitor jet reaction force under different working conditions. Furthermore, the jet reaction forces are used to analyze the roll stability of urban firefighting vehicle by combining virtual prototype technology, which has not been studied in past publications. The firefighting vehicle rollover angle is 33.8 $$^\circ$$ when the fire water monitor is not in operation, and the angles decrease from 8.5% to 39.2% when the flow rate increases from 30 L/s to 120 L/s, respectively, compared with a flow rate equal to 0 L/s. Thus, these findings facilitate analyze of jet reaction forces under different flow rates to improve the safety performance of fire fighting vehicles.

Effect of perturbation amplitudes on water film stiffness coefficients of water-lubricated plain journal bearings based on CFD–FSI methods

A numerical three-dimensional computational fluid dynamics-fluid structure interaction (CFD-FSI) model including lining deformation and cavitation is developed to evaluate the effect of perturbatio...

STUDY OF MINIMAL EFFECTIVE REEFING RATIO BASED ON AN EMPIRICAL FORMULA AND FLUID-STRUCTURE-INTERACTION METHOD

The reefing ratio for the first stage of a parachute limits the reefing ratio for the subsequent stages, so its minimal effective value is very important. In this paper, an empirical formula is derived to calculate the minimal effective reefing ratio. The empirical parameters are obtained by the arbitrary Lagrangian–Eulerian/fluid–structure interaction (ALE/FSI) method. By using the FSI method, the typical flow and structure fields of effective and ineffective reefed parachutes are revealed. The numerical results including drag characteristics and final shape are very consistent with wind tunnel tests. The curves of the empirical parameters with reefing ratios are obtained. The minimal effective reefing ratio obtained by the empirical formula is consistent with that of the numerical results, which shows that the empirical formula has high accuracy.