Tengfei Sun¹, Deli Gao^1,2, Hui Zhang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.1, pp. 37-46, 2013, DOI:10.3970/cmes.2013.090.037

Abstract Well profile design is one of the critical technologies in extended reach drilling (ERD), because an optimum well profile is an effective means for reducing the torque, drag and cost. This paper proposes a new well profile based on an inverse proportional function, and the new profile design method is analyzed in detail. The new well profile is also compared with other existing well profiles in many aspects such as the hook load, the maximum well curvature, the well length, the torque and so on. The results show that the well profile design based on More >

Deli Gao¹, Fengwu Liu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.1, pp. 17-36, 2013, DOI:10.3970/cmes.2013.090.017

Abstract A down-hole tubular string in an inclined wellbore, under variable axial and torsional loading, may simultaneously undergo a sinusoidal as well as helical buckling, at different sections. In this paper, the buckling equation for a tubular string, in an inclined wellbore, subjected to axial and torsional loading, is established by an equilibrium method. The analytical solutions for the buckling equations, for sinusoidal and helical configurations of buckled tubular string, are obtained by Galerkin and nonlinear scaling methods. Methods for computing the contact forces between the buckled tubular string and wellbore, are developed. The analytical solutions More >

Xuejun Hou^1,2, Deli Gao^1,3, Zhonghou Shen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.1, pp. 1-16, 2013, DOI:10.3970/cmes.2013.090.001

Abstract Diesel tail gas drilling (DTGD) is a type of gas drilling, which uses diesel tail gas (DTG) as a circulating medium. Its cost is slightly higher than that of air drilling, but is cheaper than those of nitrogen drilling and natural gas drilling. When the reservoir is drilled with DTG, just as nitrogen and natural gas, the DTG will prevent the burning and blasting of oil and gas in the bottom hole. In order to reduce costs, the DTG is often used in drilling the reservoir, to prevent the underground explosion. This paper analyzes the… More >

Harijono Djojodihardjo¹, Irtan Safari²

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.3, pp. 205-234, 2013, DOI:10.3970/cmes.2013.091.205

Abstract A series of work has been carried out to develop the foundation for the computational scheme for the calculation of the influence of the acoustic disturbance to the aeroelastic stability of the structure. The generic approach consists of three parts. The first is the formulation of the acoustic wave propagation governed by the Helmholtz equation by using boundary element approach, which then allows the calculation of the acoustic pressure on the acoustic-structure boundaries. The structural dynamic problem is formulated using finite element approach. The third part involves the calculation of the unsteady aerodynamics loading on More >

S.M. Moussavinezhad¹, Farzad Shahabian¹, Seyed Mahmoud Hosseini^2,3

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.3, pp. 177-204, 2013, DOI:10.3970/cmes.2013.091.177

Abstract In this article, the propagation of elastic wave is studied in two dimensional functionally graded thick hollow cylinder with finite length subjected to mechanical shock loading, considering two dimensional variations for mechanical properties. The meshless local Petrov-Galerkin (MLPG) method is developed to solve the boundary value problem. The Newmark finite difference method is used to treat the time dependence of the variables for transient problems. The FG cylinder is considered to be under axisymmetric conditions. The mechanical properties of FG cylinder are assumed to vary across thickness and length of FG cylinder in terms of… More >

António Tadeu^1,2, Julieta António¹, Patrícia Ferreira³

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.3, pp. 153-176, 2013, DOI:10.3970/cmes.2013.091.153

Abstract This paper presents an iterative coupling between a formulation based on the normal derivative of the integral equation (TBEM) and the method of fundamental solutions (MFS) for the transient analysis of acoustic wave propagation problems in the presence of multiple inclusions. The proposed formulation overcomes the individual limitations of each method, requires less computer memory and may use less CPU time than a full direct coupling formulation scheme. In the proposed formulation each inclusion is solved individually, successively, using the TBEM or the MFS and scatters a field that it is seen as an incident… More >

Po-Jen Su¹, Cha’o-Kung Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 135-151, 2013, DOI:10.3970/cmes.2013.091.135

Abstract The residual correction method is used to predict the temperature distribution of non-Fourier heat transfer with time-dependent boundary condition. The approximate solution of temperature field is obtained by the residual correction method based on the maximum principle in combination with the finite difference method, making it easier and faster to obtain upper and lower approximations of exact solutions, and even can provide clear definitions of the maximum error bounds of the approximate solutions. The proposed method is found to be an effective numerical method with satisfactory accuracy. More >

Souli, M.¹, Aquelet, N.², Al-Bahkali, E.³, Moatamedi, M.⁴

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 119-133, 2013, DOI:10.3970/cmes.2013.091.119

Abstract To simulate accurately a pressure wave propagation problem, a fine mesh is required in order to capture peak pressures accurately. This may require a very large size problem with several millions of elements. To reduce CPU time and prevent high mesh distortion, a two-dimensional problem for blast ignition and pressure propagation is performed first on a fixed Eulerian mesh. When the pressure wave gets closer to the structure, a three dimensional ALE simulation follows, where the fluid mesh and structure mesh at the fluid structure interface are coincident. The three dimensional problem is performed after… More >

J.H. Lv¹, Y. Miao^1,2, H.P. Zhu¹

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 101-117, 2013, DOI:10.3970/cmes.2013.091.101

Abstract The accurate and efficient evaluation of nearly singular integrals is one of the major concerned problems in the implementation of the boundary element method (BEM). Among the various commonly used nonlinear transformation methods, the distance transformation technique seems to be a promising method to deal with various orders of nearly singular integrals both in potential and elasticity problems. In this paper, some drawbacks of the conventional distance transformation, such as the sensitivity to the position of projection point, are investigated by numerical tests. A general distance transformation technique is developed to circumvent these drawbacks, which More >

Banghua Yao^1,2, Jianping Wei¹, Dengke Wang¹, Dan Ma^2,3, Zhanqing Chen²

CMES-Computer Modeling in Engineering & Sciences, Vol.91, No.2, pp. 81-100, 2013, DOI:10.3970/cmes.2013.091.081

Abstract Presently, there is an increasing number of water outburst accidents in China as mining activity continues to develop to deeper ground. In these accidents, water outburst caused by karst collapse columns often results in serious damage, involving both the loss of lives and significant economic loss. Therefore, it is of utmost importance to study the seepage property and water outburst mechanism of karst collapse columns. In this paper, based on the seepage theory and the groundwater dynamic theory of porous media, a fluid-solid coupling model for karst collapse columns was built and then imported into… More >