Browsing by Author "Hsu, KH"

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Development of a parallel Poisson's equation solver with adaptive mesh refinement and its application in field emission prediction
(2006-06-15)
Hsu, KH
;
Chen, PY
;
Hung, CT
;
Chen, LH
;
Wu, JS
A parallel electrostatic Poisson's equation solver coupled with parallel adaptive mesh refinement (PAMR) is developed in this paper. The three-dimensional Poisson's equation is discretized using the Galerkin finite element method using a tetrahedral mesh. The resulting matrix equation is then solved through the parallel conjugate gradient method using the non-overlapping subdomain-by-subdomain scheme. A PAMR module is coupled with this parallel Poisson's equation solver to adaptively refine the mesh where the variation of potentials is large. The parallel performance of the parallel Poisson's equation is studied by simulating the potential distribution of a CNT-based triode-type field emitter. Results with similar to 100 000 nodes show that a parallel efficiency of 84.2% is achieved in 32 processors of a PC-cluster system. The field emission properties of a single CNT triode- and tetrode-type field emitter in a periodic cell are computed to demonstrate their potential application in field emission prediction. (c) 2006 Elsevier B.V. All rights reserved.
Evaporation model of a single hydrocarbon fuel droplet due to ambient turbulence at intermediate Reynolds numbers
(2003-11-01)
Wu, JS
;
Hsu, KH
;
Kuo, PM
;
Sheen, HJ
;
機械工程學系
A general evaporation model of a single liquid fuel droplet under various ambient turbulence conditions at intermediate droplet Reynolds numbers is proposed combining the current and previous experimental results. Extensive evaporation experiments of single fuel droplets are conducted at room temperature in quasi-laminar and turbulent environments at Reynolds numbers in the range of 72-333. Tested hydrocarbon fuels include by pentane, hexane, heptane, octane and decane. Flow fields, behind a perforated plate or a circular disk in a vertical low-speed wind tunnel, provide the required ambient turbulent environments for droplet evaporation experiments. The ambient turbulence intensities vary in the range of 1-60% and the integral length scales in the range of 0.5-20 times of the initial droplet diameter. Results show that normalized evaporation rate (K/K-L) decreases with increasing effective Damkohler number (0.0001 < Da(v) < 0.1) and is approximately equal to unity with further increasing Damkohler number (0.1 < Da(v) < 1). (C) 2003 Elsevier Ltd. All rights reserved.