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 the structure using generic unsteady… More >

Sushil Mohan Ratnaker¹, Sanjay Mittal^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.80, No.3&4, pp. 179-200, 2011, DOI:10.3970/cmes.2011.080.179

Abstract Flow past a circular cylinder looses stability at Re ~ 47 via Hopf bifurcation. The eigenmode responsible for the instability leads to the von Kármán vortex shedding. In this work the linear stability of the flow to other modes, near the critical Re, is investigated. In particular, the study explores the possibility of modes other than the Kármán mode having the largest growth rate for Re < Re_cr. To this extent, global linear stability analysis (LSA) of the steady flow past a circular cylinder is carried out for Re = 45 and 48. In addition to the Kármán modes, two… More >

Chun-Lang Yeh¹

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.3, pp. 175-210, 2010, DOI:10.3970/cmes.2010.067.175

Abstract Previous studies of nano-scale liquid threads have almost entirely been devoted to the investigation of a single liquid thread in a periodic fundamental cell. This paper is the first to study the vaporization process of two nano-scale liquid threads coexisting in a periodic fundamental cell by molecular dynamics (MD) simulation. Because of the interaction between the two liquid threads, the vaporization process is different from that of a single liquid thread in a periodic fundamental cell. This study discusses the influences of the liquid thread radius, fundamental cell length, and relative position of the two threads. Snapshots of molecules, the… More >

Xie Ming-Liang^1,2, Chan Tat-Leung², Yao Fu-Yuan³

CMES-Computer Modeling in Engineering & Sciences, Vol.67, No.1, pp. 39-54, 2010, DOI:10.3970/cmes.2010.067.039

Abstract A Fourier-Chebyshev Petrov-Galerkin spectral method is described for computation of temporal linear stability in a circular jet. The outer boundary of unbounded domains is truncated by large enough diameter. The mathematical formulation is presented in detail focusing on the analyticity of solenoidal vector field used for the approximation of the flow. The scheme provides spectral accuracy in the present cases studied and the numerical results are in agreement with former works. More >

Caibin Zeng¹, Qigui Yang¹

CMES-Computer Modeling in Engineering & Sciences, Vol.59, No.1, pp. 65-78, 2010, DOI:10.3970/cmes.2010.059.065

Abstract In this paper, a fractional order model is established to describe HIV internal viral dynamics involving HAART effect. First, the model is proved to possess non-negative solutions as desired in any population dynamics. Then, a detailed analysis is carried out to study the stability of equilibrium points. Numerical simulations are presented to illustrate the stability analysis. More >

Hua Li¹, Shantanu S. Mulay¹, Simon See²

CMES-Computer Modeling in Engineering & Sciences, Vol.54, No.2, pp. 147-200, 2009, DOI:10.3970/cmes.2009.054.147

Abstract In this paper, the stability characteristics of a novel strong-form meshless method, called the random differential quadrature (RDQ), are studied using the location of zeros or roots of its characteristic polynomials with respect to unit circle in complex plane by discretizing the domain with the uniform or random field nodes. This is achieved by carrying out the RDQ method stability analysis for the 1st-order wave, transient heat conduction and transverse beam deflection equations using both the analytical and numerical approaches. The RDQ method extends the applicability of the differential quadrature (DQ) method over irregular domain, discretized by randomly or uniformly… More >

A. Carpinteri¹, M. Paggi^1,2, G. Zavarise³

CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.3, pp. 303-326, 2009, DOI:10.3970/cmes.2009.053.303

Abstract The stick-slip instability is a typical manifestation of the nonlinearity of the frictional response of rough surfaces. As recently demonstrated by several researchers, the problem of contact loss is also inherently connected to the stick-slip instability and it has been detected both in elastically soft materials, such as rubber or gelatine, and in elastic stiff materials, such as for earthquake faults. Treating the problem of tangential contact in the framework of micromechanical contact models, the effect of the phenomenon of contact loss on the micro-slip behavior of rough surfaces is herein investigated. To this aim, the stick and slip components… More >

Bhaskar Kumar¹, Sanjay Mittal^1,2

CMES-Computer Modeling in Engineering & Sciences, Vol.53, No.2, pp. 95-122, 2009, DOI:10.3970/cmes.2009.053.095

Abstract The steady flow past a circular cylinder is investigated. Symmetry conditions are imposed along the centerline of the flow field. The variation of the structure of the recirculation zone with the Reynolds number is studied. The effect of the location of lateral boundary on the flow is analyzed and compared with results from earlier studies. The eddy length varies linearly with Re. Three kinds of solutions, based on eddy structure, are found for different location of the lateral boundary. Global linear stability analysis has been carried out in a translating frame to determine the convective modes for flow past a… More >

Rubén Avila¹, Eduardo Ramos², S. N. Atluri³

CMES-Computer Modeling in Engineering & Sciences, Vol.51, No.1, pp. 73-92, 2009, DOI:10.3970/cmes.2009.051.073

Abstract A Chebyshev Tau numerical algorithm is presented to solve the perturbation equations that result from the linear stability analysis of the convective motion of a fluid layer that appears when an unconfined solid melts in the presence of gravity. The system of equations that describe the phenomenon constitute an eigenvalue problem whose accurate solution requires a robust method. We solve the equations with our method and briefly describe examples of the results. In the limit where the liquid-solid interface recedes at zero velocity the Rayleigh-Bénard solution is recovered. We show that the critical Rayleigh number Ra_c and the critical wave… More >

Chun-Lang Yeh ¹

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.3, pp. 253-284, 2009, DOI:10.3970/cmes.2009.050.253

Abstract This paper investigates the instability of a liquid thread by molecular dynamics (MD) simulation. The influences of liquid thread radius, fundamental cell length, and temperature are discussed. Snapshots of molecules, number of liquid particles formed, and density field are analyzed. Two linear stability criteria, namely Rayleigh's stability criterion and Kim's stability criterion, are accessed for their validity in molecular scale. It is found that a liquid thread is more unstable and produces more liquid particles in the fundamental cell when it is thinner or at a higher temperature. In addition, a liquid thread with a longer fundamental cell length is… More >