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曾忠

微重力空间实验和晶体生长方面的流体力学实际课题

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姓名：曾忠
目前身份：
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学位：
学术头衔：

博士生导师
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学科领域：

流体力学
研究兴趣：微重力空间实验和晶体生长方面的流体力学实际课题

个人简介

　曾忠，1993.7 硕士毕业于重庆大学工程力学系，2000.3 博士毕业于日本东北大学金属材料研究所，2000.4-2005.3 在日本东北大学金属材料研究所做研究工作。2004.9-现在在重庆大学任教授、博导。
　　近年来科研工作主要集中在微重力空间实验和晶体生长方面的流体力学实际课题，分为如下三大部分：1）提出了"数值同位素模型"：根据同位素跟踪的思想，提出了"数值同位素"数学模型，并将该模型数值程序化，用于将对流数字可视化；2）Floating Zone ：（1）提出了新的引入自由表面张力的数学模型，（2）纯热张力对流的相似性解，（3）混合浮力流和热张力对流的相似解问题，（4）提出了涡对物理模型，（5）对失稳后的热张力对流的振荡频率异常突变的解释；3）Czochralski：（1）固体紫外光材料LiCaAlF6晶体的优化生长条件研究，（2）不同的晶体旋转速度下，对流的时空结构的转换，（3）Czochralski晶体生长中，非平衡自由表面张力对三维振荡对流的影响。

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2009-05-22

【期刊论文】Three-dimensional unsteady convection in LiCaAlF6-Czochralski growth

曾忠， Zhong Zenga， b， *， Jingqiu Chena， Hiroshi Mizusekib， Tsuguo Fukudac， Yoshiyuki Kawazoeb

Journal of Crystal Growth 266(2004)81-87，-0001，（）：

-1年11月30日

摘要

By means of the finite volume method, the evolution of the three-dimensional unsteady convection with increasing crystal rotation is simulated numerically for LiCaAlF6 in a model of Czochralski crystal growth. The effect of Marangoni convection on the flow structure features is investigated, and the results indicate that ignoring Marangoni convection causes a large deviation.

A1.， Computer simulation， A1.， Convection， A1.， Fluid flows， A1.， Marangoni convection， A2.， Czochralski method， B1.， Fluoride single crystal

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2009-05-22

【期刊论文】Three-dimensional oscillatory convection of LiCaAlF6 melts in Czochralski crystal growth

曾忠， Zhong Zenga， b， *， Jingqiu Chena， Hiroshi Mizusekib， Kiyoshi Shimamurab， c， Tsuguo Fukudab， d， Yoshiyuki Kawazoeb

Journal of Crystal Growth 252(2003)538-549，-0001，（）：

-1年11月30日

摘要

Three-dimensional (3D) unsteady mixed thermal buoyancy, Marangoni and forced convection of LiCaAlF6 (LiCAF) melts (Prandtl number PrE1.4) are investigated numerically for model set up typically for Czochralski crystal growth. With increasing crystal rotation rate, convection evolves from steady axisymmetric to three-dimensional oscillatory convection with varying spatio-temporal features. The details of the oscillatory convection structures are presented.

A1.， Computer simulation， A1.， Convection， A1.， Fluid flows， A1.， Marangoni convection， A2.， Czochralski method， B1.， Fluoride single crystal

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2009-05-22

【期刊论文】Usefulness of experiments with model fluid for thermocapillary convectionFeffect of Prandtl number on two-dimensional thermocapillary convection

曾忠， Zhong Zenga， *， Hiroshi Mizusekia， Kiyoshi Shimamuraa， Tsuguo Fukudaa， Yoshiyuki Kawazoea， Kazuyuki Higashinob

Journal of Crystal Growth 234(2002)272-278，-0001，（）：

-1年11月30日

摘要

The floating zone technique is promising to realize large, high-quality crystals under microgravity. Thermocapillary flow, which is the dominant convection in a floating zone under microgravity, has been widely reported in the literature to be extremely sensitive to the Prandtl number Pr: In the present study, the effect of Pr on steady thermocapillary convection is re-evaluated based on both analytical and numerical solutions. The results indicate that an approximate similarity of temperature and velocity structures in a large Pr range is realized under suitable conditions, fixing the Marangoni number Ma; in steady two-dimensional regime.

A1.， Computer simulation， A1.， Fluid flow， A1.， Heat transfer， A1.， Marangoni convection， A1.， Thermocapillary convection， A2.， Floating zone technique

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2009-05-22

【期刊论文】Structure Similarity of Mixed Buoyancy-Thermocapillary Flow in Half-Zone Liquid Bridge

曾忠， Zhong Zeng， *， Hiroshi Mizuseki， Kazuyuki Higashino， Kiyoshi Shimamura， Tsuguo Fukuda and Yoshiyuki Kawazoe

Materials Transactions, Vol. 42, No.11 (2001) pp. 2322 to 2331，-0001，（）：

-1年11月30日

摘要

The mixed buoyancy-thermocapillary flow in a half-zone liquid bridge with the dynamic Bond number Bd≈α(1) is investigated numerically by the finite volume method. The similarities of temperature and velocity structures are realized under conditions of fixed Marangoni and Rayleigh numbers in steady two-dimensional regime for a suitable Prandtl number range.

thermocapillary convection,， Marangoni convection,， floating zone,， half-zone,， buoyancy,， similarity,， nature convection

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2009-05-22

【期刊论文】Three-dimensional oscillatory thermocapillary convection in liquid bridge under microgravity

曾忠， Zhong Zenga， *， Hiroshi Mizusekia， Kiyoshi Simamuraa， Tsuguo Fukudaa， Kazuyuki Higashinob， Yoshiyuki Kawazoea

International Journal of Heat and Mass Transfer 44(2001)3765-3774，-0001，（）：

-1年11月30日

摘要

Three-dimensional oscillatory thermocapillary convection in silicone oil liquid bridge is studied numerically by means of finite volume method (FVM). The results reveal the existence of two different oscillatory modes: pulsating and rotating oscillations. Close to the onset of oscillation, the pulsating oscillatory convection is observed. With the increment of Marangoni number Ma, the pulsating oscillatory convection is replaced by rotating oscillatory convection, where the temperature and velocity fields demonstrate the characteristics of rotation. An approximately linear relationship between Ma and dimensionless main frequency f*=fH2χ1 is found for As=4.0 in periodic oscillatory regime. This relationship becomes a little more complex for As=1.0.

Thermocapillary， Marangoni convection， Microgravity， Instability， Floating zone， Half-zone， Liquid bridge

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2009-05-22

【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

摘要

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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2009-05-22

【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

摘要

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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2009-05-22

【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

摘要

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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2009-05-22

【期刊论文】Quantum size effect and temperature effect on spin-polarized transport in ZnSe/Zn1–xMnxSe multilayers

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

摘要

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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2009-05-22

【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

摘要

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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2009-05-22

【期刊论文】Three-dimensional oscillatory convection of LiCaAlF6 melts in Czochralski crystal growth

曾忠， Zhong Zenga， b， *， Jingqiu Chena， Hiroshi Mizusekib， Kiyoshi Shimamurab， c， Tsuguo Fukudab， d， Yoshiyuki Kawazoeb

Journal of Crystal Growth 252(2003)538-549，-0001，（）：

-1年11月30日

摘要

A1.， Computer simulation， A1.， Convection， A1.， Fluid flows， A1.， Marangoni convection， A2.， Czochralski method， B1.， Fluoride single crystal

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2009-05-22

【期刊论文】Three-dimensional unsteady convection in LiCaAlF6-Czochralski growth

曾忠， Zhong Zenga， b， *， Jingqiu Chena， Hiroshi Mizusekib， Tsuguo Fukudac， Yoshiyuki Kawazoeb

Journal of Crystal Growth 266(2004)81-87，-0001，（）：

-1年11月30日

摘要

A1.， Computer simulation， A1.， Convection， A1.， Fluid flows， A1.， Marangoni convection， A2.， Czochralski method， B1.， Fluoride single crystal

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2009-05-22

【期刊论文】Three-dimensional oscillatory thermocapillary convection in liquid bridge under microgravity

曾忠， Zhong Zenga， *， Hiroshi Mizusekia， Kiyoshi Simamuraa， Tsuguo Fukudaa， Kazuyuki Higashinob， Yoshiyuki Kawazoea

International Journal of Heat and Mass Transfer 44(2001)3765-3774，-0001，（）：

-1年11月30日

摘要

Thermocapillary， Marangoni convection， Microgravity， Instability， Floating zone， Half-zone， Liquid bridge

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2009-05-22

【期刊论文】Usefulness of experiments with model fluid for thermocapillary convectionFeffect of Prandtl number on two-dimensional thermocapillary convection

曾忠， Zhong Zenga， *， Hiroshi Mizusekia， Kiyoshi Shimamuraa， Tsuguo Fukudaa， Yoshiyuki Kawazoea， Kazuyuki Higashinob

Journal of Crystal Growth 234(2002)272-278，-0001，（）：

-1年11月30日

摘要

A1.， Computer simulation， A1.， Fluid flow， A1.， Heat transfer， A1.， Marangoni convection， A1.， Thermocapillary convection， A2.， Floating zone technique

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2009-05-22

【期刊论文】Structure Similarity of Mixed Buoyancy-Thermocapillary Flow in Half-Zone Liquid Bridge

曾忠， Zhong Zeng， *， Hiroshi Mizuseki， Kazuyuki Higashino， Kiyoshi Shimamura， Tsuguo Fukuda and Yoshiyuki Kawazoe

Materials Transactions, Vol. 42, No.11 (2001) pp. 2322 to 2331，-0001，（）：

-1年11月30日

摘要

thermocapillary convection,， Marangoni convection,， floating zone,， half-zone,， buoyancy,， similarity,， nature convection

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2009-05-22

【期刊论文】Size effect on quasibound states and negative differential resistances in step-barrier structures

曾忠， Yong Guo a， b， )， Bing-Lin Gu a， Zhong Zeng b， Yoshiyuki Kawazoe b

Physics Letters A 261(1999)114-118，-0001，（）：

-1年11月30日

摘要

Electronic states and tunneling properties in step-barrier structures have been investigated. The results indicate that there exists quasibound states in step-barrier structure both at zero bias and under an applied bias. Size effect on negative-differential resistances is examined and the condition for obtaining larger current peak-to-valley ratios has been discussed.

Heterojunctions， Resonant tunneling， Quasibound states， Negative-differential resistance

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2009-05-22

【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

摘要

Marangoni convection， Thermocapillary， Floating zone， Half-zone

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2009-05-22

【期刊论文】ESWL实际焦点位置的理论和数值分析

曾忠，陈景秋，赵万星

中国生物医学工程学报，2004，23（3）：247～251，-0001，（）：

-1年11月30日

摘要

从理论和数值模拟两个方面分析了ESWL中的非线性的动力学焦点和实际焦点的位置，给出三种典型的动力学焦点的数值结果，说明非线性动力学焦点和实际焦点一般不是几何焦点,指出正确确定实际焦点在ESWL技术中的重要性。

体外冲击波碎石，实际焦点，动力学焦点

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2009-05-22

【期刊论文】Resonant tunneling in step-barrier structures under an applied electric field

曾忠， Yong Guoa)， Bing-Lin Gu， Jing-Zhi Yu， Zhong Zeng， and Yoshiyuki Kawazoe

JOURNAL OF APPLIED PHYSICS VOLUME 84, NUMBER 2 15 JULY 1998，-0001，（）：

-1年11月30日

摘要

Resonant tunneling in step-barrier structures is investigated by using the transfer-matrix technique. The formulas for the transmission coefficient and the current density are derived when taking into account the coupling between components of the motion of an electron in directions parallel and perpendicular to the interfaces. By making a detailed comparison of resonant tunneling among single square-barrier structures, asymmetric double-barrier structures, and step-barrier structures, the tunneling properties in step-barrier structures are revealed. It is shown that the global behavior of step-barrier structures obtained resembles that of asymmetric double-barrier structures, and step-barrier structures are superior to both single- and double-barrier structures in many aspects. In comparison to asymmetric double-barrier structures, step-barrier structures have several features, such as a wider negative-differential resistance region, easier fabrication, high-speed response, and a relatively lower transmission coefficient and current peak-to-valley ratios. Moreover, higher resonant bias is required in order to obtain optimal transmission resonances in the step-barrier structure. The results shown in this work not only shed new light on the physics of resonant tunneling in electric-barrier structures but are also helpful in designing quantum devices based on step-barrier tunneling structures.

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2009-05-22

【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

摘要

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