Syeda Humaira Tasnim^a,*, Shohel Mahmud^b, Roydon Andrew Fraser^a

Frontiers in Heat and Mass Transfer, Vol.2, No.1, pp. 1-10, 2011, DOI:10.5098/hmt.v2.1.3006

Abstract In this paper, we experimentally measure the temperature fields at different locations on the stack plate and in the surrounding working fluid in a standing wave thermoacoustic device. The temperature measurements at the stack extremities and at the neighboring gas show axial heat transfer at the stack extremities, as opposed to the hypothesis of a perfectly isolated stack used in the linear thermoacoustic theory. Four different mechanisms of heat transfer are identified at the stack extremities in the present study. This information is necessary for the optimization of the performances of practical thermoacoustic engines. For More >

Lin LU, Bin TENG, Bing CHEN

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 133-134, 2011, DOI:10.3970/icces.2011.019.133

Abstract This work describes the numerical implements of a two-dimensional viscous numerical wave flume, which is based on the Finite Element Method (FEM), Computational lagrangian-Eulerian Advection Remap Volume of Fluid Method (CLEAR-VOF), internal wave generation and artificial wave damping technique. Owning to the inherent consistence of CLEAR-VOF with FEM, the present numerical model allows the simulations of wave propagation and interaction with structures to be simulated with irregular mesh partition. The present numerical wave flume is validated by several applications in comparisons with available experimental data and numerical results, including the problems of standing wave trains More >

Takahide Nakamura

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.4, pp. 115-116, 2011, DOI:10.3970/icces.2011.019.115

Abstract No limitation exists virtually in target size for the classical simulation of atoms with the O(N) algorithms on parallel machines. On the other hand, the time step cannot be changed and hence the total simulation time still remains short. It is meaningful to increase the time step by the coarse-graining the atomic system. The coarse-grained particle (CGP) method has been proposed for such purposes, but it is applicable only to crystalline solids at zero-temperature limit [1,2]. The total energy of the CGP system is defined as the statistical ensemble average of the atomistic Hamiltonian under… More >

Weiqiu CHEN

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.4, pp. 125-126, 2011, DOI:10.3970/icces.2011.018.125

Abstract We will report a theory of surface piezoelectricity which governs a plane surface of a piezoelectric body. The piezoelectric surface may be endowed with different properties from the bulk material, and can account for the well-known surface effect which becomes increasingly important in micro- or nano-sized structures. In this study, the surface is treated as a piezoelectric thin layer of thickness h, and the state-space formulism is adopted to obtain the transfer relation between the state vectors at the top and bottom surfaces of the layer. The power series of the transfer matrix is then More >

Jinyou Xiao, Wenjing Ye

The International Conference on Computational & Experimental Engineering and Sciences, Vol.18, No.4, pp. 101-102, 2011, DOI:10.3970/icces.2011.018.101

Abstract Traditional boundary element methods (BEMs) suffer from densely populated system matrices. In recent years, acceleration techniques like the wavelet BEM (WBEM) have been developed which reduce the complexity considerably. In WBEM, one uses appropriate wavelet bases for the discretization, yielding numerically sparse matrices which result in extremely fast matrix-vector multiplications. However, in conventional WBEM the wavelets are constructed by uniform refinement of parametrically described patches. Such approaches have difficulties in dealing with practical problems with complicated geometries because patch-wise surface parameterization is generally not available. To avoid this limitation, Tausch proposed a method in [1]… More >

Younho Cho, Weibin Li, Bin Yang

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.2, pp. 49-50, 2011, DOI:10.3970/icces.2011.017.049

Abstract This paper aims at an experimental method for detecting thermal-damages in a tube-like structure using acoustic nonlinear parameter of ultrasonic guided waves. The material nonlinearity of aluminum pipe specimens, which have been subjected to different heat-loading cycles, is measured to characterize the micro-damages. Flexible Polyvinylidene Fluoride (PVDF) comb transducers are used to generate and receive the fundamental and second harmonic waves. The amplitude of the second harmonic wave is extracted from the Fast Fourier Transform (FFT) spectrum of a received signal. The measured relative nonlinear parameter increases monotonically as a function of the propagation distance, More >

LIN Xiao-Ping, LEI Zhen-Kun, LIU Zeng-Hua, WU Zhan-Jun

The International Conference on Computational & Experimental Engineering and Sciences, Vol.17, No.1, pp. 29-30, 2011, DOI:10.3970/icces.2011.017.029

Abstract Recently, a technology named ultrasonic guided wave has a rapid development and wide application. It is more and more popular for the advantage compared with traditional detection. An enormous amount of work has contributed to our current understanding of wave propagation. The case of a hollow cylinder loaded by the outside liquid has been considered by Rose et al. Kwun investigated the propagation of guided waves in water filled pipes. C. Aristegui discussed propagation of guided waves in fluid-filled pipe surrounded by different fluids. Lafleur and Shields have studied the propagation of low frequency modes… More >

Lifeng Wang, Haiyan Hu, Wanlin Guo

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.1, pp. 15-16, 2011, DOI:10.3970/icces.2011.020.015

Abstract The wave dispersions of longitudinal and flexural wave propagations in single-walled and multi-walled carbon nanotubes are studied in the frame of continuum mechanics and molecular dynamics simulation. The dispersion relations between the phase velocity, group velocity and the wave number for the flexural and longitudinal waves, described by a beam model and a cylindrical shell model, are established for both single- and multi-walled carbon nanotubes. The effect of micro-structures in carbon nanotubes on the wave dispersion is revealed through the non-local elastic models of beam and cylindrical shell including the second order gradient of strain… More >

Peter Hess, Alexey M. Lomonosov, AndrAC Moura, Peter V. Grigoriev

The International Conference on Computational & Experimental Engineering and Sciences, Vol.20, No.1, pp. 3-4, 2011, DOI:10.3970/icces.2011.020.003

Abstract Crack generation by the steep shock fronts of laser-induced nonlinear surface acoustic wave (SAW) pulses and their nondestructive evaluation (NDE) by short linear SAW pulses was studied experimentally and theoretically. With the contactfree laser-based photoacoustic pump-probe technique, nondestructive testing could be extended to the characterization of elastic-shock-generated partially closed microcracks in the range of tens of micrometers.

By numerical simulations the propagation of thermoelastically launched broadband SAW pulses in nonlinear media and the initiation of crack growth is described. The characteristic features of SAW profiles in linear media, nonlinear media with quadratic nonlinearity, and nonlinear… More >

Q.W. Ma

The International Conference on Computational & Experimental Engineering and Sciences, Vol.19, No.1, pp. 15-16, 2011, DOI:10.3970/icces.2011.019.015

Abstract Over the past several years, the research group led by the author has extended the MPLG (Meshless Local Petrov-Galerkin) method developed by Prof. Atluri and his group to model nonlinear water waves; and then made further development to produce a method called MLPG_R (Meshless Local Petrov-Galerkin method based on Rankine source solution) method. In order to improve the computational efficiency of the method for modelling nonlinear water waves, several techniques have been developed. They include (1) introduction of a weak form of governing equation that does not contain derivatives of unknown functions; (2) a new More >