유체-고체 상호작용 해석을 위한 계면요소의 개발

김현규(Hyun-Gyu Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.11

This paper presents a new approach to simulate fluid-solid interaction problems involving non-matching interfaces. The coupling between fluid and solid domains with dissimilar finite element meshes consisting of 4-node quadrilateral elements is achieved by using the interface element method (IEM). Conditions of compatibility between fluid and solid meshes are satisfied exactly by introducing the interface elements defined on interfacing regions. Importantly, a consistent transfer of loads through matching interface element meshes guarantees the present method to be an efficient approach of the solution strategy to fluid-solid interaction problems. An arbitrary Lagrangian-Eulerian (ALE) description is adopted for the fluid domain, while for the solid domain an updated Lagrangian formulation is considered to accommodate finite deformations of an elastic structure. The stabilized equal order velocity-pressure elements for incompressible flows are used in the motion of fluids. Fully coupled equations are solved simultaneously in a single computational domain. Numerical results are presented for fluid-solid interaction problems involving nonmatching interfaces to demonstrate the effectiveness of the methodology.

Study on bidirectional fluid-solid coupling characteristics of reactor coolant pump under steady-state condition

Xiuli Wang,Yonggang Lu,Rongsheng Zhu,Qiang Fu,Haoqian Yu,Yiming Chen 한국원자력학회 2019 Nuclear Engineering and Technology Vol.51 No.7

The AP1000 reactor coolant pump is a vertical shielded-mixed flow pump, is the most important coolant power supply and energy exchange equipment in nuclear reactor primary circuit system, whose steady-state and transient performance affect the safety of the whole nuclear island. Moreover, safety demonstration of reactor coolant pump is the most important step to judge whether it can be practiced, among which software simulation is the first step of theoretical verification. This paper mainly introduces the fluid-solid coupling simulation method applied to reactor coolant pump, studying the feasibility of simulation results based on workbench fluid-solid coupling technology. The study found that: for the unsteady calculations of the pure liquid media, the average head of the reactor coolant pump with bidirectional fluid-solid coupling decreases to a certain extent. And the coupling result is closer to the real experimental value. The large stress and deformation of rotor under different flow conditions are mainly distributed on impeller and idler, and the stress concentration mainly occurs at the junction of front cover plate and blade outlet. Among the factors that affect the dynamic stress change of rotor, the pressure load takes a dominant position.

Research on air diversion channel of air-cooled gasoline engine cylinder head and simulation of fluid- solid coupling heat transfer

Du B. C.,Tang G. Z.,Zhang L.,Zhong L.,Deng T.,Yi Y. L. 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.11

In view of the problem that local temperature of the original cylinder head is on the high side, an innovative cooling air diversion channel is proposed. The cooling air diversion channel introduces cool air into the cylinder head to forcedly cool the cylinder head. Furthermore, the multiple guide plates are set to reasonably distribute cold air in the air diversion channel. In addition, appropriately increase the length of the fins to cooling the whole cylinder head. The fluid-solid coupling three-dimensional simulation technology is adopted to analyze the impact of the new air diversion channel on the heat dissipation of cylinder head. Finally, the optimal scheme is defined to fabricate the prototype. Simulations results show that the above improvements make the temperature in the high temperature region effectively decrease, and the cooling performance of whole cylinder head is enhanced. In the optimal improvement scheme, the highest temperature of cylinder head decrease by 23 K. Furthermore, the prototype was fabricated according to the optimal scheme. The experimental results show that the temperature of the improved cylinder head decreased effectively, and the highest temperature decreased by 20.4 K. The simulation results are in agreement with the experimental results, and the maximum error is less than 5 percent.

2D time-domain acoustic-elastic coupled modeling: a cell-based finite-difference method

이호용,Seung-Chul Lim,Dong-Joo Min,Byung-Doo Kwon,Minkyu Park 한국지질과학협의회 2009 Geosciences Journal Vol.13 No.4

To describe wave propagation in a fluid-solid environment which is usually encountered during marine seismic exploration, we design a time-domain acoustic-elastic coupled modeling algorithm based on the cell-based finite-difference method. The cell-based method has proven to delineate stress-free conditions correctly at the free surface with just changes in the material properties, which indicates that it can also properly deal with subsurface interface boundaries. In the acoustic-elastic coupled modeling, we first compose finite differences individually for the acoustic and elastic media; we then combine the differences using fluid-solid interface boundary conditions. Numerical experiments show that the cell-based coupled modeling algorithm gives solutions compatible with analytic solutions and that it properly describes S- and converted waves as well as P-waves. Applying the cell-based coupled modeling algorithm to a slope model, we confirm that our coupled modeling algorithm describes irregular interfaces properly, although it employs a staircase approximation of them.

Temperature Effect of Concrete Hydration Heat under Atmospheric Wind Based on Fluid-Solid Coupling

Moyan Zhang,Hong Xiao,Meng Wang,Mahantesh M. Nadakatti,Peng Chen 대한토목학회 2022 KSCE JOURNAL OF CIVIL ENGINEERING Vol.26 No.3

Concrete inevitably gets subjected to the effects of atmospheric wind during pouring. It is a significant factor to predict the temperature stress and gradient of concrete structure during pouring. In this paper, the Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) were used to analyze the temperature and stress generated by temperature gradient of mass cap concrete under the wind environment. Then, the reliability of the temperature value was verified by the field test. The analysis shows that the use of the fluid-solid coupling method allows considering not only the thermal movement and thermodynamic properties of wind (given by CFD), but also the thermal expansion and stress of the concrete structure (given by FEM). Because of the wind, temperature of the windward side of the concrete is lower than that of the leeward side. Highest temperature is located at the center biased towards the leeward side. Increase in the wind speed increases the temperature difference and the maximum principal tensile stress. However, the study shows that change in the wind direction has limited effect on the concrete temperature stress.

Mechanical properties and cushioning mechanism of shear thickening fluid

Peng Zhao,Qian Chen,Xue Gao,Zhaoyong Wu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11

Shear thickening fluid (STF) is one type of dispersed system with rapidly changing rheological properties under an impulse load. The apparent viscosity of such a suspension system changes dramatically under high-speed impact, and the system can even change from suspension to quasi-solid. Once the load is removed, the STF will quickly return to its original state. In this paper, a mechanical model based on a particle-jammed model and added mass was proposed by calculating the acceleration response of the impact bar, and the local hardening phenomenon of STF in the low-speed impact test was interpreted. Then with the low-speed impact test, the rheological properties of STF in the cushioning process were recorded by a high-speed camera. Meanwhile, a comparison was made with the cushioning efficiency of AV-200, a closed-cell foam material, by using the force-displacement curve. Finally, based on the constitutive relation of STF and by using the fluid-solid coupling method in the FEM, the lowspeed impact test of STF was analyzed to obtain more comprehensive dynamic characteristics. The acceleration response obtained in the test was consistent with the theoretical results, which further verified the rationality and effectiveness of the theoretical model. Compared with AV-200, STF has a cushioning efficiency of 50 %-60 %, and its cushioning performance was superior to AV-200. Starting with the rheological cloud map of STF and the acceleration response of the impact bar by the numerical model, a comparison was made with the results of low-speed impact test, and a good agreement is observed.

Improved Vibration Suppression Modeling for Reinforcement Clamping by Eco-friendly Magnetorheological Fluid During Milling of Annular Thin-Walled Workpiece

Xiaohui Jiang,Kun Wu,Yong Zhang,Shirong He 한국정밀공학회 2022 International Journal of Precision Engineering and Vol.9 No.6

Milling vibration will greatly affect the milling accuracy and surface quality of thin-walled workpiece. Considering that the characteristics of instant curing high-efficiently under the action of magnetic field and can be recycled without wasted of magnetorheological fluid (MRF), a MRF composite clamping to suppress milling vibration is proposed in this paper. Based on the fluid–solid coupling dynamics theory, the dynamics modal of the MRF clamping is established. On this basis, considering the influences of the filling volume of MRF to processing vibration, the suppression effect of MRF on milling vibration is analyzed in time domain and frequency domain, respectively. A series of simulations and experiments are carried out on typical annular thin-walled workpiece, the result shows that the maximum increase of natural frequency of thin-walled workpiece is 53.1% while filling with MRF, and Ra, Rz, Rq decreased by 36.1%, 14.8% and 16.7%, respectively. The consequence verified the reliability and effectiveness of the proposed method in the whole milling process.

Analysis on Geo-stress and casing damage based on fluid-solid coupling for Q9G3 block in Jibei oil field

Ji, Youjun,Li, Xiaoyu Techno-Press 2018 Geomechanics & engineering Vol.15 No.1

Aimed at serious casing damage problem during the process of oilfield development by injecting water, based on seepage mechanics, fluid mechanics and the theory of rock mechanics, the multi-physics coupling theory was also taken into account, the mathematical model for production of petroleum with water flooding was established, and the method to solve the coupling model was presented by combination of Abaqus and Eclipse software. The Q9G3 block in Jibei oilfield was taken for instance, the well log data and geological survey data were employed to build the numerical model of Q9G3 block, the method established above was applied to simulate the evolution of seepage and stress. The production data was imported into the model to conduct the history match work of the model, and the fitting accuracy of the model was quite good. The main mechanism of casing damage of the block was analyzed, and some wells with probable casing damage problem were pointed out, the displacement of the well wall matched very well with testing data of the filed. Finally, according to the simulation results, some useful measures for preventing casing damage in Jibei oilfield was proposed.

Analysis of the fluid-solid-thermal coupling of a pressurizer surge line under ocean conditions

Yu Hang,Zhao Xinwen,Fu Shengwei,Zhu Kang 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

To investigate the effects of ocean conditions on the thermal stress and deformation caused by thermal stratification of a pressurizer surge line in a floating nuclear power plant (FNPP), the finite element simulation platform ANSYS Workbench is utilized to conduct the fluid-solid-thermal coupling transient analysis of the surge line under normal “wave-out” condition (no motion) and under ocean conditions (rolling and pitching), generating the transient response characteristics of temperature distribution, thermal stress and thermal deformation inside the surge line. By comparing the calculated results for the three motion conditions, it is found that ocean conditions can significantly improve the thermal stratification phenomenon within the surge line, but may also result in periodic oscillations in the temperature, thermal stress, and thermal deformation of the surge line. Parts of the surge line that are more susceptible to thermal fatigue damage or failure are determined. According to calculation results, the improvements are recommended for pipeline structure to reduce the effects of thermal oscillation caused by ocean conditions. The analysis method used in this study is beneficial for designing and optimizing the pipeline structure of a floating nuclear power plant, as well as for increasing its safety.

Morphology characterization of micro-gap oil film of tilting pad hydrostatic bearing under extreme working conditions

Xiaodong Yu,Yanan Feng,Yan Zhao,Dianbin Huang,Jianhua Jiao 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.12

Taking the hydrostatic support of the tiltable oil pad double rectangular cavity as the object, the fluid-thermal-solid coupling deformation analysis of the friction pair is carried out, and the three-dimensional morphology of the micro-gap oil film is obtained. An oil film thickness test device is built to verify the rationality of the numerical simulation method. It is found that the elastic deformations of rotational workbench and base under extreme loads are both concave deformations, the thermal deformations are both convex deformations, and the maximum thermal deformation is mainly concentrated on the outer oil sealing edge. The deformation of the downstream side oil sealing edge is higher than that of the reverse side oil sealing edge. The minimum oil film thickness is the minimum distance between the downstream side oil sealing edge and the lower surface of the hydrostatic guideway of the rotational workbench, where tribological failure is prone to occur.