Browsing by Author "CHIEN, CH"

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SPATIOTEMPORAL SOLITARY PULSES IN GRADED-INDEX MATERIALS WITH KERR NONLINEARITY
(1995-08-15)
YU, SS
;
CHIEN, CH
;
LAI, YC
;
WANG, YP
;
光電工程學系
We analyze spatio-temporal pulse propagation in graded-index Kerr materials with the variational method, and find that if the path of propagation provides negative group-velocity dispersion, stable solitary pulses exist for pulse energy smaller than a critical value, Spatial and temporal degrees of freedom cannot be analyzed separately due to their coupling through the Kerr nonlinarity. Our unified analysis not only elucidates the hidden coupling, but also clarifies relations between parameters of the solitary pulse. The analysis is verified by direct numerical simulation of the paraxial wave equation.
STABLE 4-DIMENSIONAL SOLITONS IN GRADED-INDEX MATERIALS WITH KERR NONLINEARITY
(1994)
LAI, YC
;
CHIEN, CH
;
WANG, JP
;
光電工程學系
;
Department of Photonics
UNSTEADY THERMOSOLUTAL OPPOSING CONVECTION OF A LIQUID WATER MIXTURE IN A SQUARE CAVITY .1. FLOW FORMATION AND HEAT AND MASS-TRANSFER CHARACTERISTICS
(1993-03-01)
CHANG, J
;
LIN, TF
;
CHIEN, CH
;
交大名義發表
;
機械工程學系
Transient thermosolutal opposing convection of a liquid- water mixture in a square cavity subject to horizontal temperature and concentration gradients is numerically investigated by a third-order upwind finite-difference scheme. Results are particularly presented to illustrate the effects of the Lewis and Grashof numbers on the evolution of flow patterns and the associated heat and mass transfer characteristics for solutally dominant situations. Results for Le = 100 clearly show the double-diffusive nature of the convection. In the initial stage the flow is dominated by the interface velocities at the vertical side walls driven by the concentration gradients there. Later, the flow is governed by the thermal buoyancy. At a much later time, the solutal buoyancy set in inducing new recirculating cells along the side walls. These cells gradually grow and squeeze the thermally driven cell in the core region. Multilayer flow structure is finally formed. The counterrotating cells resulting from the opposing thermal and solutal buoyancies cause significant velocity, temperature and concentration oscillations with time at high Grashof numbers.