Liang Yang^*, Tianle Xi, Zhixing Wang

FDMP-Fluid Dynamics & Materials Processing, Vol.19, No.6, pp. 1585-1608, 2023, DOI:10.32604/fdmp.2023.024987

Abstract The VOF method is used to simulate the dynamics of a droplet interacting with a structure consisting of an array of microcolumns mounted on a flat surface. Such a specific configuration is intended to mimic the typical properties of lotus leaves, which typically display regularly arranged micron-scale papillary structures. After setting the initial velocity of the simulated droplet on the basis of practical considerations, an analysis is conducted about the effect of the characteristic size of the microstructure on the apparent contact angle. The pressure variation in the microstructure caves is also examined. The simulation results show that the change… More >

Dehui Tong^1,2, Shunshun Qin^1,2,*, Quan Liu^1,2, Yuhan Li³, Jiewei Lin^2,3

FDMP-Fluid Dynamics & Materials Processing, Vol.18, No.6, pp. 1667-1682, 2022, DOI:10.32604/fdmp.2022.019768

Abstract Avoiding cavitation inside the water jacket is one of the most important issues regarding the proper design of a diesel engine’s cylinder liner. Using CFD simulations conducted in the frame of a mixture multiphase approach, a moving grid technology and near-wall cavitation model, in the present study the factors and fluid-dynamic patterns that influence cavitation are investigated from both macroscopic and mesoscopic perspectives. Several factors are examined, namely: wall vibration, water jacket width, initial cavitation bubble radius, coolant temperature, and number of bubbles. The results show that reducing the cylinder liner vibration intensity can significantly weaken the cavitation. Similarly, increasing… More >

Lei Liu^*, Chuanhui Huang, Xinghua Lu, Ping Yu, Longhai Li, Huafeng Guo

FDMP-Fluid Dynamics & Materials Processing, Vol.17, No.2, pp. 501-509, 2021, DOI:10.32604/fdmp.2021.015161

Abstract In order to study the effect of Al₂O₃ nanoparticles in the cavitation-based strengthening process of magnesium alloys, the impact of a micro-jet generated by bubble collapse has been considered. The strengthening mechanism is based on the transfer of the energy of cavitation due to bubble collapse to Al₂O₃ particles, which then undergo collision with the surface of the sample. The hardness, surface morphology, element content and chemical state of the strengthened samples have been analyzed by microhardness tests, SEM (scanning electron microscopy) and XPS (X-ray photoelectron spectroscopy) techniques. The results show that: after 5 min of strengthening, nanoparticles can be… More >

Yezhi Qin, Ying Wang, Zhikai Wang^*, Xiongliang Yao

CMES-Computer Modeling in Engineering & Sciences, Vol.126, No.3, pp. 1093-1123, 2021, DOI:10.32604/cmes.2021.012969

Abstract The shock wave of the underwater explosion can cause severe damage to the ship structure. The propagation characteristics of shock waves near the structure surface are complex, involving lots of complex phenomena such as reflection, transmission, diffraction, and cavitation. However, different structure surface boundaries have a significant effect on the propagation characteristics of pressure. This paper focuses on investigating the behavior of shock wave propagation and cavitation from underwater explosions near various structure surfaces. A coupled Runge–Kutta discontinuous Galerkin (RKDG) and finite element method (FEM) is utilized to solve the problem of the complex waves of fluids and structure dynamic… More >

Lei Liu^*, Ping Yu

FDMP-Fluid Dynamics & Materials Processing, Vol.16, No.2, pp. 211-224, 2020, DOI:10.32604/fdmp.2020.08168

Abstract High-flow hydraulic one-way valves in water pipes are typically used to mitigate conditions, which would otherwise cause vibration and cavitation erosion after long-term operation. To prevent cavitation and enhance the performance of hydraulic one-way valves, in the present work a dedicated experimental study has been conducted. The structural parameters relating to the pilot valve core, the main valve core, and the through-flow section of the considered flow channel have been changed to analyse reverse impact, and cavitation, characteristics. The results show that the control pressure has a weak effect on the cavitation characteristics, while changes in the structural parameters can… More >

Xu Liu¹, Xiaoyang Chen^{1, *}, Rongyu Kang¹, Xuejin Shen¹, Ben Ni²

CMES-Computer Modeling in Engineering & Sciences, Vol.123, No.1, pp. 129-152, 2020, DOI:10.32604/cmes.2020.07836

Abstract In this paper, the oscillatory oil squeeze film is taken as a research object, and a coupled cavitation model based on the theory of bubble dynamics and hydrodynamic lubrication is used and a specific method of numerical calculation is given. Then the parallel-plate squeeze film test apparatus is used to validate the coupled cavitation model. The pictures of the cavitation were captured by a high-speed camera and then processed to obtain the variation of the cavitation area in experiments. Compared with the experimental results, the model can successfully predict the process of generation and development of cavitation. At the same… More >

X. Liu, A. Scarpas¹

CMES-Computer Modeling in Engineering & Sciences, Vol.9, No.1, pp. 57-74, 2005, DOI:10.3970/cmes.2005.009.057

Abstract Numerical investigations of strain localization have been performed on 3D dense fully saturated sand specimens subjected to triaxial loading and simultaneous inflow or outflow conditions. The role of the water suction field on the formation and evolution of strain localization is addressed computationally. It has been shown that, in a porous medium, the fluid (water) phase plays indeed an important role in strain localization. The formation and evolution of strain localization are influenced both by the material behaviour of the solid component and the interaction between components. In this contribution, after a presentation of the incremental formulation of the coupled… More >

Fanghui Shi, Rohit Paranjpe¹

CMES-Computer Modeling in Engineering & Sciences, Vol.3, No.4, pp. 507-516, 2002, DOI:10.3970/cmes.2002.003.507

Abstract This paper describes an implicit finite element cavitation algorithm. The cavitation problem is formulated using the complementarity form. By using the complementarity formulation, the fluid pressure in the non-cavitation region and the density of the air/fluid mixture in the cavitation region are solved simultaneously. The stream-wise biasing approach is used to produce oscillation-free solution at the fluid film reformation boundary. Implicit scheme is implemented to yield stability for time marching. The algorithm is compared with the established finite volume methods, and the robustness and the correctness of the algorithm is verified. More >

D. Gawin¹, L. Sanavia²

CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.3, pp. 255-302, 2009, DOI:10.3970/cmes.2009.053.255

Abstract This paper presents a unified mathematical approach to model the hydro-thermo-mechanical behavior of saturated and partially saturated porous media by considering the effects of air dissolved in liquid water. The model equations are discretized by means of the Finite Element method. A correspondingly updated code is used to analyze two examples; the first one is the well known Liakopoulos test, i.e. the drainage of liquid water from a 1m column of sand, which is used to validate numerically the model here developed. As second example, a biaxial compression test of undrained dense sands where cavitation takes place at strain localization… More >

X.G. Yuan^1,2, H.W. Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.32, No.3, pp. 175-184, 2008, DOI:10.3970/cmes.2008.032.175

Abstract In this paper, a dynamic problem that describes void formation and motion in an incompressible hyperelastic solid sphere composed of a transversely isotropic Valanis-Landel material is examined, where the sphere is subjected to a class of periodic step tensile loads on its surface. A motion equation of void is derived. On analyzing the dynamical properties of the motion equation and examining the effect of material anisotropy on void formation and motion in the sphere, we obtain some new and interesting results. Firstly, under a constant surface tensile load, it is proved that a void would form in the sphere as… More >