Browsing by Author "TSUI, YY"

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A STUDY OF UPSTREAM-WEIGHTED HIGH-ORDER DIFFERENCING FOR APPROXIMATION TO FLOW CONVECTION
(1991-07-05)
TSUI, YY
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交大名義發表
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機械工程學系
;
National Chiao Tung University
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Department of Mechanical Engineering
This paper is concerned with a number of upstream-weighted second- and third-order difference schemes. Also considered are the conventional upwind and central difference schemes for comparison. It commences with a general difference equation which unifies all the given first-, second- and third-order schemes. The various schemes are evaluated through the use of the general equation. The unboundedness and accuracy of the solutions by the difference schemes are assessed via various analyses: examination of the coefficients of the difference equation, Taylor series truncation error analysis, study of the upstream connection to numerical diffusion, single-cell analysis. Finally, the difference schemes are tested on one- and two-dimensional model problems. It is shown that the high-order schemes suffer less from the problem of numerical diffusion than the first-order upwind difference scheme. However, unboundedness cannot be avoided in the solutions by these schemes. Among them the linear upwind difference scheme presents the best compromise between numerical diffusion and solution unboundedness.
CALCULATION OF TURBULENT-FLOW THROUGH ENGINE INLET PORTS
(1992-09-01)
TSUI, YY
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LEE, SY
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交大名義發表
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機械工程學系
;
National Chiao Tung University
The flow in an axisymmetric assembly of an engine intake port and valve is under investigation, using multidimensional analysis. The model is formulated in a curvilinear coordinate system and solved with nonstaggered grids. The turbulent effects are characterized by the k-epsilon model. The epsilon equation is modified to emphasize the effects of the normal stresses. The modification results in reduction of the turbulence and length scale in the valve passage and improves the computational accuracy for the cases considered.
FLOW MODELING IN TURBOFAN MIXING DUCT
(1994-08-01)
TSUI, YY
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WU, PW
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LIAO, CW
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機械工程學系
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Department of Mechanical Engineering
A computational procedure is described to study the mixing flow in a multilobe turbofan mixer. The predictions have been obtained using a finite volume method to solve the density-weighted lime-averaged Navier-Stokes equations. Turbulence is characterized by the k-epsilon eddy viscosity model. To fit the irregular boundaries of the flow field, the curvilinear nonorthogonal coordinates are employed. The robustness of the computational procedure is enhanced by making use of nonstaggered grids. Results shaw that the streamwise vortex generated at the exit of the lobes dominates the performance of the mixing process. Comparison with experimental data indicates that good predictions can be obtained provided that sufficient inlet conditions are given.