Xiangyu Gao, Weidong Yang^*, Hongxuan Xian, Xiyuan Tu, Yuanyuang Wang^*

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.1, pp. 227-241, 2020, DOI:10.32604/cmes.2020.09923

Abstract This paper studies the binder droplet injection process in the 3DP technique. The mathematical model of the binder penetration process for multi-nozzle and multi-layer in 3DP technique is established, by using the conservation Level set method. According to the two-dimensional plane model of three-dimensional spatial structure of sand bed, the construction method of an equivalent cylindrical mapping infiltration model is proposed to represent the porosity of the model in the two-dimensional plane, which is exactly the same as that in the three-dimensional space, as well as closer to the arrangement of the three-dimensional space, and to realize the differentiation between… More >

Chen Yu¹, Qifu Wang^{1, ∗}, Chao Mei¹, Zhaohui Xia¹

CMES-Computer Modeling in Engineering & Sciences, Vol.122, No.3, pp. 779-803, 2020, DOI:10.32604/cmes.2020.09363

Abstract This paper proposes a multiscale isogeometric topology optimization (ITO) method where the configuration and layout of microstructures are optimized simultaneously. At micro scale, a shape deformation method is presented to transform a prototype microstructure (PM) for obtaining a series of graded microstructures (GMs), where microstructural skeleton based on the level set framework is applied to retain more topology features and improve the connectability. For the macro scale calculation, the effective mechanical properties can be estimated by means of the numerical homogenization method. By adopting identical non-uniform rational basis splines (NURBS) as basis functions for both parameterized level set model and… More >

Hans Mühlhaus¹, Laurent Bourgouin¹, Alina Hale¹

The International Conference on Computational & Experimental Engineering and Sciences, Vol.3, No.4, pp. 225-232, 2007, DOI:10.3970/icces.2007.003.225

Abstract We use a finite element formulation of the level set method to model the evolution of the free surface of axi-symmetric spreading flows of highly viscous media on a horizontal plane. We consider specifically the growth of a lava dome as an example however similar problems also occur in flows involving the spreading of molten metals or ceramics. Here we restrict ourselves on constant viscosity fluids for simplicity. In real lavas or melts the viscosity is highly temperature dependent. This manifests itself in the formation of thin predominantly elastic-plastic boundary layers along the free (cold) surfaces of the spreading flows.… More >

Jia Dongyao^1,2, Zhu Huaihua¹, Ai Yanke¹, Zou Shengxiong¹

CMES-Computer Modeling in Engineering & Sciences, Vol.103, No.6, pp. 411-427, 2014, DOI:10.3970/cmes.2014.103.411

Abstract The existing study on the image segmentation methods based on the image of vehicle lights is insufficient both at home and abroad, and its segmentation efficiency and accuracy is low as well. On the basis of the analysis of the regional characteristics of vehicle lights and a level set model, an image segmentation method for complex vehicle lights based on adaptive significance level set contour model is proposed in this paper. Adaptive positioning algorithm of the significant initial contour curve based on two-dimensional convex hull is designed to obtain the initial position of evolution curve, thus the adaptive ability of… More >

Shaohua Zhang^1,2, Pei Li¹, Yongteng Zhong¹, Jiawei Xiang^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.101, No.1, pp. 17-31, 2014, DOI:10.3970/cmes.2014.101.017

Abstract In order to obtain smooth boundary and improve computational efficiency, a new topology optimization scheme based on the level set method is presented. Using the level set function as design variable and the volume ratio of the solid material as volume constraint, respectively, this scheme can easily implement compliance minimization structure topology optimization in associated with the reaction-diffusion equation in commercial software COMSOL. Compared with the results of solid isotropic material with penalization (SIMP) and traditional level set method, this scheme obtained a smooth geometry boundary. In the present computational scheme, the computational cost could be enormously saved without solving… More >

Ashraf Balabel¹

CMES-Computer Modeling in Engineering & Sciences, Vol.95, No.4, pp. 283-302, 2013, DOI:10.3970/cmes.2013.095.283

Abstract This paper presents the numerical results obtained from the numerical simulation of turbulent liquid jet atomization due to three distinctly different types of liquid jets/air orientations; namely, coflow jet, coaxial jet and the combined coflow-coaxial jet. The applied numerical method, developed by the present authors, is based on the solution of the Reynolds-Averaged Navier Stokes (RANS) equations for time-dependent, axisymmetric and incompressible two-phase flow in both phases separately and on regular and structured cell-centered collocated grids using the control volume approach. The transition from one phase to another is performed through a consistent balance of the interfacial dynamic and kinematic… More >

Qiang Li¹

CMES-Computer Modeling in Engineering & Sciences, Vol.94, No.3, pp. 207-224, 2013, DOI:10.32604/cmes.2013.094.207

Abstract In this paper, an immersed boundary method (IBM) has been developed to simulate three-dimensional (3D) complex flows in the injection molding process, in which the irregular boundary of mould is treated by a level set function. The melt front (melt-air interface) is captured and treated using the coupled level set and volume of fluid (CLSVOF) method. The finite volume method on the nonstaggered meshes is implemented to solve the governing equations, and the melt filling process is simulated in a rectangular mould with both thick- and thin-wall sections. The numerical result shows good agreement with the available data. Finally, the… More >

Ashraf Balabel¹,

CMES-Computer Modeling in Engineering & Sciences, Vol.89, No.4, pp. 283-301, 2012, DOI:10.3970/cmes.2012.089.283

Abstract This paper presents a novel numerical method for solving the twophase flow problems with moving interfaces in either laminar or turbulent flow regimes. The developed numerical method is based on the solution of the Reynolds- Averaged Navier Stokes equations in both phases separately with appropriate boundary conditions located at the interface separating the two fluids. The solution algorithm is performed on a regular and structured two-dimensional computational grid using the control volume approach. The complex shapes as well as the geometrical quantities of the interface are determined via the level set method. The numerical method is firstly validated against the… More >

Hokyung Shim¹, Vinh Thuy Tran Ho^1,,Semyung Wang^1,2, Daniel A. Tortorelli³

CMES-Computer Modeling in Engineering & Sciences, Vol.37, No.2, pp. 175-202, 2008, DOI:10.3970/cmes.2008.037.175

Abstract This paper presents a topological shape optimization technique for electromagnetic problems using a level set method and radial basis functions. The proposed technique is a level set (LS) based optimization dealing with geometrical shape derivatives and topological design. The shape derivative is computed by an adjoint variable method to avoid numerous sensitivity evaluations. A level set model embedded into the scalar function of higher dimensions is propagated to represent the design boundary of a domain. The level set function interpolated into a fixed initial domain is evolved by using the Hamilton-Jacobi equation. The moving free boundaries (dynamic interfaces) represented in… More >

S.Y. Wang^1,2, M.Y. Wang³

CMES-Computer Modeling in Engineering & Sciences, Vol.13, No.2, pp. 119-148, 2006, DOI:10.3970/cmes.2006.013.119

Abstract In this paper, an implicit free boundary parametrization method is presented as an effective approach for simultaneous shape and topology optimization of structures. The moving free boundary of a structure is embedded as a zero level set of a higher dimensional implicit level set function. The radial basis functions (RBFs) are introduced to parametrize the implicit function with a high level of accuracy and smoothness. The motion of the free boundary is thus governed by a mathematically more convenient ordinary differential equation (ODE). Eigenvalue stability can be guaranteed due to the use of inverse multiquadric RBF splines. To perform both… More >