A. Kidess¹, N. Armour¹, S. Dost^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.7, No.1, pp. 29-56, 2011, DOI:10.3970/fdmp.2011.007.029

Abstract When a metallic liquid is subject to strong magnetic body forces, the issues of convergence and numerical stability may arise in numerical simulations. Handling of magnetic body force terms needs care. In this work we have studied two open codes and discussed the related issues. Magnetic force and mass transport terms were added to these codes. Handling the stability issues was discussed. The developed systems were validated by two benchmark cases. Then, the dissolution process of silicon into the germanium melt was selected as an application. The objective was the numerical study of the dissolution More >

Zone-Ching Lin¹and Ren-Yuan Wang¹

CMC-Computers, Materials & Continua, Vol.16, No.3, pp. 247-272, 2010, DOI:10.3970/cmc.2010.016.247

Abstract The paper establishes a new three-dimensional quasi-steady molecular statics nanoscale abrasive cutting model to investigate the abrasive cutting behavior in the downpressing and abrasive cutting process of a workpiece in chemical mechanical polishing (CMP) process. The downpressing and abrasive cutting process is a continuous process. The abrasive cutting process is done after the single abrasive particle has downpressed and penetrated a workpiece to a certain depth of a workpiece. The paper analyzes the effects of the abrasive particles with different diameters on action force. It also analyzes the action force change of abrasive particles with… More >

Youngmin Lee, Jae Shin Park, Seyoung Im

The International Conference on Computational & Experimental Engineering and Sciences, Vol.10, No.2, pp. 51-52, 2009, DOI:10.3970/icces.2009.010.051

Abstract We study energetics and mobility of dislocations in silicon crystal in atomistic scale. The electronic structure of silicon affects its dynamics, so that it is analyzed with tight-binding method for high accuracy, emerged as a useful method for studying structural and dynamical properties of covalent systems. The tight biding potential used for silicon crystalline is the one of GSP known as a transferable potential. Due to the nature of rare events, the analysis is executed by action-derived molecular dynamics (ADMD) calculations. The changes of the system energy due to dislocation glide are explored with a More >

Tai-Ming Chang¹, Chien-Chou Weng¹, Mei-Jiau Huang^1,2, Chun-KaiLiu², Chih-Kuang Yu²

CMES-Computer Modeling in Engineering & Sciences, Vol.50, No.1, pp. 47-66, 2009, DOI:10.3970/cmes.2009.050.047

Abstract We employ the non-equilibrium molecular dynamics (NEMD) simulation to calculate the in-plane thermal conductivity of silicon thin films of thickness 2.2nm and 11nm. To eliminate the finite-size effect, samples of various lengths are simulated and an extrapolation technique is applied. To perform the quantum correction which is necessary as the MD simulation temperature is lower than Debye temperature, the confined phonon spectra are obtained in advance via the EMD simulations. The investigation shows the thermal conductivities corrected based on the bulk and thin-film phonon densities of states are very close and they agree excellently with More >

N. Armour¹, S. Dost^1,2

FDMP-Fluid Dynamics & Materials Processing, Vol.5, No.4, pp. 331-344, 2009, DOI:10.3970/fdmp.2009.005.331

Abstract A combined numerical and experimental investigation has been undertaken to explore the benefits of an applied static magnetic field on Silicon transport into a Germanium melt. This work utilized a similar material configuration to that used in the Liquid Phase Diffusion (LPD) and Melt-Replenishment Czochralski (Cz) growth systems. The measured concentration profiles from the samples processed with and without the application of magnetic field showed very similar shape. The amount of silicon transport into the melt is slightly higher in the samples processed under magnetic field, and there is a substantial difference in dissolution interface… More >

Liming Xiong¹, Youping Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 203-214, 2008, DOI:10.3970/cmes.2008.024.203

Abstract This paper presents the application of an atomistic field theory (AFT) in modeling and simulation of boron- , boron/nitrogen and silicon/nitrogen-doped nanocrystalline silicon carbide (B-, BN-, SiN-SiC). Intergranular glassy films (IGFs) and nano-sized pores have been obtained in triple junctions of the grains in nanocrystalline SiC (nc-SiC). Residual tensile stress in the SiC grains and compressive stress in the grain boundaries (GBs) are observed. Under uniaxial tension, the constitutive responses of nanocrystalline SiC were reproduced from the simulations. It is found that the mechanical properties of nanocrystalline SiC are strongly dependent on the compositions of More >

T. J. Jaber¹, M. Z. Saghir¹

FDMP-Fluid Dynamics & Materials Processing, Vol.2, No.3, pp. 175-190, 2006, DOI:10.3970/fdmp.2006.002.175

Abstract The study deals with three-dimensional numerical simulations of fluid flow and heat transfer under the effect of a rotating magnetic field (RMF) during the growth of Ge_0.98Si_0.02 by the traveling solvent method (TSM). By using a RMF, an attempt is made to suppress buoyancy convection in the Ge_0.98Si_0.02 solution zone in order to get high quality and homogeneity with a flat growth interface. The full steady-state Navier-Stokes equations, as well as the energy, mass transport and continuity equations, are solved numerically using the finite element method. Different magnetic field intensities (B=2, 4, 10, 15 and 22 More >

Koichi Kakimoto, Lijun Liu

FDMP-Fluid Dynamics & Materials Processing, Vol.2, No.3, pp. 167-174, 2006, DOI:10.3970/fdmp.2006.002.167

Abstract This paper deals with the investigation of the flow instability of molten silicon in a magnetic field during crystal growth by means of the Czochralski method. The flow exhibits a three-dimensional structure due to a transverse non-axisymmetric pattern of the magnetic field. The melt-crystal interface is found to be nearly two-dimensional. The azimuthal non-uniformity of the temperature field is much weaker on the crystal and crucible sidewalls in the case of high rotation rates of crucible and crystal than in the case of non-rotating crucible and crystal. More >

C. W. Lan¹, B. C. Yeh

FDMP-Fluid Dynamics & Materials Processing, Vol.1, No.1, pp. 33-44, 2005, DOI:10.3970/fdmp.2005.001.033

Abstract The suppression of unstable Marangoni convection in floating-zone crystal growth by magnetic fields has enjoyed over recent years a widespread use as a reliable and useful strategy. A transversal direction of the field is particularly efficient, but asymmetric zone shapes and thus segregation are induced. Counter-rotation of the feed and of the crystal rods is a common way to improve dopant homogeneity. However, its effects under magnetic fields are complex and have not yet been studied in detail. In the present analysis, three-dimensional (3D) simulations based on a finite-volume/multigrid method are used to illustrate the More >

Selden B. Crary¹, Peter Cousseau², David Armstrong¹, David M. Woodcock³, Eva H. Mok¹, Olivier Dubochet⁴, Philippe Lerch⁴, Philippe Renaud²

CMES-Computer Modeling in Engineering & Sciences, Vol.1, No.1, pp. 127-140, 2000, DOI:10.3970/cmes.2000.001.127

Abstract We present a new and unique software capability for finding statistical optimal designs of deterministic experiments on continuous cuboidal regions. The objective function for the design optimization is the minimization of the expected integrated mean squared error of prediction of the metamodel that will be found, subsequent to the running of the computer simulations, using the best linear unbiased predictor (BLUP). The assumed response-model function includes an unknown, stochastic term, Z. We prove that this criterion, which we name I_Z-optimality, is equivalent to I-optimality for non-deterministic experiments, in the limit of zero correlations among the Z's for More >