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【期刊论文】Marangoni convection in model of floating zone under microgravity
曾忠, Z. Zenga, *, H. Mizusekia, K. Shimamuraa, K. Higashinob, T. Fukudaa, Y. Kawazoea
Journal of Crystal Growth 229(2001)601-604,-0001,():
-1年11月30日
Marangoni convection in a half-zone model, a simplification of the floating zone model, is steady and axisymmetric for Marangoni number Ma5Mac, but the azimuthal flow after instability (Ma>Mac) breaks the axial-symmetry, and m-foldsymmetry of the flow pattern is observed. The symmetry number m (azimuthal wave number) depends strongly on the aspect ratio, As (As=height/radius), of the half-zone. Based on the results of numerical simulation, the nature of the correlation between m and As is investigated.
A1., Convection, A1., Fluidflows, A1., Heat transfer, A2., Floating zone technique
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【期刊论文】Direct numerical simulation of oscillatory Marangoni convection in cylindrical liquid bridges
曾忠, Z. Zenga, *, H. Mizusekia, K. Higashinob, Y. Kawazoea
Journal of Crystal Growth 204(1999)395-404,-0001,():
-1年11月30日
A three-dimensional oscillatory Marangoni (thermocapillary) convection with Prandtl number Pr=16.0849 and Marangoni number Ma"3.30508]104 in a large aspect ratio (As=H/R) range, As=0.2-4, in a silicone oil liquid bridge with a non-deformable cylindrical surface is investigated by the anite volume method. The azimuthal wave numbers 1, 2, 3, 4, 5, 6, 10 and 16 are obtained for different aspect ratios, As. The dimensionless main frequency f*p=fMa-1/2H2/k of periodic or quasi-periodic temperature oscillations strongly depends on aspect ratio, As. f*p increases with the increment of As with approximately a bi-linear relation, and its gradient for As=0.2-1 is less than that for As>1. The periodic and quasi-periodic oscillations are found to depend on aspect ratio, As, for fixed Pr and Ma.
Marangoni convection, Thermocapillary, Floating zone, Half-zone
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【期刊论文】NUMERICAL SIMULATION OF CONVECTION DEPTH IN SHEAR CELL UNDER MICROGRAVITY
曾忠, Z. Zeng, H. Mizuseki, K. Ichinoseki, K. Higashino, and Y. Kawazoe
Adv. Space Rex Vol. 24, No.10, pp. 1321-1324, 199,-0001,():
-1年11月30日
By applying the idea of an isotope trace experiment, the concept of isotope trace in hydrodynamics simulation is proposed. The isotope concentration is conceived as a numerical marker to trace the convection and estimate numerically the convection depth due to shearing in shear cell under microgravity. Two different shearing rates, 2mm/s and 20mm/s, are investigated, and results demonstrate that the isotope depths are same for both cases at the termination of shearing, but the effect of residual flow field after shearing is different.
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曾忠, Yong Guo a, c, ∗, Jun-Qiang Lu b, Zhong Zeng c, Qian Wang c, Bing-Lin Gu a, Yoshiyuki Kawazoe c
Physics Letters A 284(2001)205-215,-0001,():
-1年11月30日
We present tight-binding Green's function investigations of the influence of quantum sizes and the temperature on spin tunneling transport through a tunable ZnSe/Zn1-xMnxSe multilayers under an external electric field. It is found that the degree of polarization can be significantly induced by the size of the corresponding structure. As the size of the multilayers is increasing, both the transmission spectra and the current density spectra become more complicated and the degree of spin polarization is higher. It is also found that the degree of the spin polarization is drastically reduced as the temperature is increasing.
Spin polarization, Tunneling, Heterojunctions, Semimagnetic semiconductor
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【期刊论文】Electron-spin polarization in magnetically modulated quantum structures
曾忠, Yong Guo, Bing-Lin Gu, Zhong Zeng, Jing-Zhi Yu, and Yoshiyuki Kawazoe
PHYSICAL REVIEW B VOLUME 62, NUMBER 4 15 JULY 2000-II,-0001,():
-1年11月30日
The spin-dependent electron resonant tunneling through magnetically modulated quantum structures has been investigated with and without an external electric field. The spin polarization is found to be strongly dependent on the magnetic configuration, the applied bias, the incident electron energy, and the incident wave vector. It is shown that an unpolarized beam of conducting electrons can be strongly polarized for an electron tunneling through magnetic-barrier structures, which is an arrangement with unidentical magnetic barriers and wells. The external electric field greatly changes the spin polarization of electrons for small electronic energies, where the electron-spin polarization exhibits considerable wave-vector-dependent features.
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