A.B. Tatomir^1,2, A.Szymkiewicz³, H. Class¹, R. Helmig¹

CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.2, pp. 81-112, 2011, DOI:10.3970/cmes.2011.077.081

Abstract We present a two phase flow conceptual model, the corresponding simulator (2pMINC) and a workflow for large-scale fractured reservoirs, based on a continuum fracture approach which uses the multiple interacting continua (MINC) method complemented with an improved upscaling technique. The complex transient behavior of the flow processes in fractured porous media is captured by subgridding the coarse blocks in nested volume elements which have effective properties calculated from the detailed representation of the fracture system. In this way, we keep a physically based approach, preserve the accuracy of the model, avoid the common use of… More >

Chein-Shan Liu¹, Chung-Lun Kuo²

CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.1, pp. 57-80, 2011, DOI:10.3970/cmes.2011.077.057

Abstract In this paper, the solutions of inverse Cauchy problems for quasi-linear elliptic equations are resorted to an unusual mixed group-preserving scheme (MGPS). The bottom of a finite rectangle is imposed by overspecified boundary data, and we seek unknown data on the top side. The spring-damping regularization method (SDRM) is introduced by converting the governing equation into a new one, which includes a spring term and a damping term. The SDRM can further stabilize the inverse Cauchy problems, such that we can apply a direct numerical integration method to solve them by using the MGPS. Several More >

Sheng Yan Li¹, Bin Gang Xu^1,2, Xiao Ming Tao¹, Hong Hu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.1, pp. 33-56, 2011, DOI:10.3970/cmes.2011.077.033

Abstract Slender yarn structure made from natural fibers, nano-fibers, carbon nanotubes or other types of fibrous materials is all formed by twisting an assembly of short or long fibers and its performance is significantly influenced by the physical behavior of these fibers in the slender yarn forming region - a small triangle area called spinning triangle. In this paper, a new generalized FEM model of spinning triangle has been developed to theoretically analyze the fiber structural and mechanical performance in fabrication of these slender yarn structures. In this proposed model, a geometrical model of spinning triangle More >

A. Rezaei Mojdehi^1,2, A. Darvizeh³, A. Basti²

CMES-Computer Modeling in Engineering & Sciences, Vol.77, No.1, pp. 1-32, 2011, DOI:10.3970/cmes.2011.077.001

Abstract In this paper, a meshless method based on the local petrov-galerkin approach is proposed for the three dimensional (3D) elasto-plastic problems. Galerkin weak-form formulation is applied to derive the discrete governing equations. A weak formulation for the set of governing equations is transformed into local integral equations on local sub-domains by using a unit test function. Nodal points are distributed in the 3D analyzed domain and each node is surrounded by a cubic sub-domain to which a local integral equation is applied. Three dimensional Moving Least-Square (MLS) approximation is used as shape function to approximate More >

W. A. El-Askary¹

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.3&4, pp. 203-232, 2011, DOI:10.3970/cmes.2011.074.203

Abstract Large eddy simulation (LES) is a viable and powerful tool to analyze unsteady three- dimensional turbulent flows. In this paper, the method of LES is used to compute a plane turbulent supersonic boundary layer subjected to different pressure gradients. The pressure gradients are generated by allowing the flow to pass in the vicinity of an expansion-compression ramp (inclined backward-facing step with leeward-face angle of 25 degrees) for an upstream Mach number of 2.9. The inflow boundary condition is the main problem for all turbulent wall-bounded flows. An approach to solve this problem is to extract… More >

Xiaowei Zeng¹

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.3&4, pp. 183-202, 2011, DOI:10.3970/cmes.2011.074.183

Abstract This paper presents an atomistic field theory and its application in modeling and simulation of nano/micro materials. Atomistic formulation and finite element implementation of the atomistic field theory is briefly introduced. Numerical simulations based on the field theory are performed to investigate the material behaviors of bcc iron at coarse-grained scale and we have obtained the mechanical strength and elastic modulus, which are in good agreement with results by first principles calculations. Also the nanoscale deformation and failure mechanism are revealed in bcc iron nanorods under simple tension. It is interesting to observe that under More >

Zhen Yang¹, Xingsheng Gu², Xiaoyi Liang^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.3&4, pp. 161-182, 2011, DOI:10.3970/cmes.2011.074.161

Abstract Mesoporous carbons are synthesized by organic-organic self-assembly of triblock copolymer F127 and a new type of carbon precursor as resorcinol-furfural oligomers. Some factors will impact the mesoporous carbons pore structure and properties were studied. The main factors, such as the ratio of triblock copolymer F127 and oligomers, degree of polymerizstry of resorcinol-furfural oligomers, the ratio of resorcinol-furfural oligomers - F/R, and their mutual relations were identified. Aimed at balancing the complex characteristic of mesoporous structure and adsorption properties, a classification and optimization model based on support vector machine is developed. The optimal operation conditions of More >

Xiao Zhao¹, Haitian Yang^1,2, Qiang Gao¹

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.2, pp. 139-160, 2011, DOI:10.3970/cmes.2011.074.139

Abstract A piecewised adaptive algorithm in the time domain is presented to solve the transient convection-diffusion heat transfer problem. By expanding all variables at a time interval, an initial and boundary value problem is decoupled into a series of recursive boundary value problems which can be solved by FEM or other well developed numerical schemes to deal with boundary value problems. A steady computing accuracy can be adaptively maintained via the power increase of the expansion, particularly when the step size varies in the whole computing process. Additionally for the nonlinear cases, there is no requirement More >

Yi W. Wan¹, Huan J. Keh²

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.2, pp. 109-138, 2011, DOI:10.3970/cmes.2011.074.109

Abstract The steady rotation of an axially symmetric particle about its axis of revolution normal to two plane walls at an arbitrary position between them in a viscous fluid is studied theoretically in the limit of small Reynolds number. The fluid is allowed to slip at the surface of the particle. A method of distribution of a set of spherical singularities along the axis of revolution inside a prolate particle or on the fundamental disk within an oblate particle is used to find the general solution for the fluid velocity distribution that satisfies the boundary conditions… More >

Gongsheng Li¹, De Yao², Hengyi Jiang³, Xianzheng Jia¹

CMES-Computer Modeling in Engineering & Sciences, Vol.74, No.2, pp. 83-108, 2011, DOI:10.3970/cmes.2011.074.083

Abstract This paper deals with an inverse problem of determining a time-depen -dent reaction coefficient arising from a disturbed soil-column infiltrating experiment based on measured breakthrough data. A purpose of doing such experiment is to simulate and study transport behaviors of contaminants when they vertically penetrating through the soils. Data compatibility of the inverse problem is discussed showing a sufficient condition to the solution's monotonicity and positivity with the help of an adjoint problem. Furthermore, an optimal perturbation regularization algorithm is applied to solve the inverse problem, and two typical numerical examples are presented to support More >