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Science china(Physics,Mechanics & Astronomy) 2005年第5期48卷 614-625页

作者： HUANG Zhangfeng 1, CAO Wei 1,2.& ZHOU Heng 1,2.1. Department of Mechanics, tianjin University, tianjin 300072. china {2., nankai University and tianjin University, tianjin 300072. china 1. Department of Mechanics Tianjin University 300072 Tianjin China 2. liu-hui center of applied mathematics Nankai University and Tianjin University 300072 Tianjin China

Temporal mode direction numerical simulation has been done for the transition of a supersonic boundary layer on a flat plate with Mach number 4.5. Analysis of the result showed that during the breakdown process in laminar-turbulent transition, the mechanism causing the mean flow profile to evolve swiftly from laminar to turbulent was that the modification of mean flow profile by the disturbances,when they became larger,led to a remarkable change of its stability characteristics. Though the most unstable T-S wave was of second mode for laminar flow, the first mode waves played the key role in the breakdown process in laminar-turbulent transition.

关键词： supersonic boundary layer, transition, breakdown.

Direct numerical simulation of a supersonic turbulent boundary layer on a flat plate and its analysis

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Science china(Physics,Mechanics & Astronomy) 2005年第5期48卷 626-640页

作者： HUANG Zhangfeng1, ZHOU Heng1,2.& LUO Jisheng1,2.1. Department of Mechanics, tianjin University, tianjin 300072. china {2., nankai University and tianjin University, tianjin 300072. china 1. Department of Mechanics Tianjin University 300072 Tianjin China 2. liu-hui center of applied mathematics Nankai University and Tianjin University 300072 Tianjin China

Temporal mode direct numerical simulation (DNS) has been done for a supersonic turbulent boundary layer on a flat plate with Mach number 4.5. It was found that the mean flow profile, the normal-wise distribution of turbulent Mach number and the root mean square (RMS) of the fluctuations of various variables, as well as the Reynolds stresses, bore similarity in nature, when the turbulence reached a fully developed state. But the compressibility effect was strong and must be considered. The strong Reynolds analogy (SRA) and the Morkovin hypothesis were no longer valid. From the end of transition to the fully developed state of turbulence, it was in the transient period, for which the similarity did not hold.

关键词： turbulence, similarity, compressibility effect, supersonic boundary layer, direct numerical simulation.

Transition prediction for supersonic and hypersonic boundary layers on a cone with angle of attack

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Science china(Physics,Mechanics & Astronomy) 2009年第8期52卷 1223-1232页

作者： SU CaiHong1 & ZHOU Heng1,2.1 Department of Mechanics,tianjin University,tianjin {2.china 2.liu-hui center of applied mathematics,nankai University and tianjin University,tianjin {2.china Department of Mechanics Tianjin University Tianjin 300072 China liu-hui {2. of applied mathematics Nankai University and Tianjin University Tianjin 300072 China

Transition prediction for boundary layers has always been one of the urgent problems waiting for a solution for the development of aero-space technology,yet there is no reliable and effective method due to the complexity of the *** eN method has been regarded as an effective method for the transition prediction of boundary ***,it heavily relies on experiment or *** in cases with three-dimensional base flow,for instance,the boundary layer on a cone with angle of attack,the result of its application is not *** authors have found its cause and proposed the method for its improvement,which did yield the fairly satisfactory result for a given test case,and also did not rely so much on experiment or ***,before people can really apply this method to practical problems,more test cases have to be *** this paper,more test cases for the application of the improved eN method to problems of transition prediction of supersonic and hypersonic boundary layers on cones with angle of attack will be *** results are compared with those obtained by experiments and/or direct numerical simulations,confirming that the improved eN method is effective and *** also find that there may be more than one ZARF for each meridian plane,and which one should be chosen for the eN method has been clarified.

关键词： angle of attack cone boundary layer transition eN method

Transition prediction of a hypersonic boundary layer over a cone at small angle of attack——with the improvement of e^N method

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Science china(Physics,Mechanics & Astronomy) 2009年第1期52卷 115-123页

作者： SU CaiHong1 & ZHOU Heng1,2.1 Department of Mechanics, tianjin University, tianjin 300072. china 2.{2.-hui center of applied mathematics, nankai University and tianjin University, tianjin 300072. china 1. Department of Mechanics Tianjin University Tianjin 300072 China 2. liu-hui center of applied mathematics Nankai University and Tianjin University Tianjin 300072 China

The problem of transition prediction for hypersonic boundary layers over a sharp cone has been studied in this work. The Mach number of the oncoming flow is 6, the cone half-angle is 5°, and the angle of attack is 1°. The conventional e N method is used, but the transition location so obtained is obviously incorrect. The reason is that in the conventional method, only the amplifying waves are taken into account, while in fact, for different meridians the decay processes of the disturbances before they begin to grow are different. Based on our own previous work, new interpretation and essential improvement for the e N method are proposed. Not only the amplification process but also the decay process is considered. The location, where by linear stability theory, the amplitude of disturbance wave is amplified from its initial small value to 1%, is considered to be the transition location. The new result for transition prediction thus obtained is found to be fairly satisfactory. It is also indicated that for the calculation of base flow, boundary layer equations can be used for a small angle of attack. Its computational cost is much smaller than those for DNS.

关键词： angle of attack cone transition eN method

On the composition operators on the Bloch space of several complex variables

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Science china mathematics 2005年第z1期48卷 392-399页

作者： ZHOU Zehua & CHE Renyu Department of mathematics, tianjin University,{2. liuhui center for applied mathematics, nankai University & tianjin University,tianjin 300072. {12. 1. Department of mathematics Tianjin University 300072 Tianjin China 2. liuhui {2. for applied mathematics Nankai University & Tianjin University 300072 Tianjin China

In this paper we first look upon some known results on the composition operator as bounded or compact on the Bloch-type space in polydisk and ball, and then give a sufficient and necessary condition for the compositio... 详细信息

关键词： Bloch space, bounded symmetric domains, composition operator, bergman metric.

Inflow conditions for spatial direct numerical simulation of turbulent boundary layers

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 1106-1115页

作者： HUANG ZhangFeng & ZHOU Heng Department of Mechanics,tianjin University,tianjin {2.china liu-hui center of applied mathematics,nankai University and tianjin University,tianjin {2.china 1. Department of Mechanics Tianjin University Tianjin 300072 China 2. liu-hui center of applied mathematics Nankai University and Tianjin University Tianjin 300072 China

The inflow conditions for spatial direct numerical simulation(SDNS) of turbulent boundary layers should reflect the characteristics of upstream turbulence,which is a puzzle. In this paper a new method is suggested,in which the flow field obtained by using temporal direct numerical simulation(TDNS) for fully developed turbulent flow(only flow field for a single moment is sufficient) can be used as the inflow of SDNS with a proper transformation. The calculation results confirm that this method is feasible and effective. It is also found that,under a proper time-space transformation,all statistics of the fully developed turbulence obtained by both temporal mode and spatial mode DNS are in excellent agreement with each other,not only qualitatively,but also quantitatively. The normal-wise distributions of mean flow profile,turbulent Mach number and the root mean square(RMS) of the fluctuations of various variables,as well as the Reynolds stresses of the fully developed turbulence obtained by using SDNS,bear similarity in nature.

关键词： inflow conditions spatial direct numerical simulation turbulent boundary layer similarity

Mechanism of Breakdown in Laminar-Turbulent Transition of Incompressible Boundary Layer on a Flat Plate

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Transactions of tianjin University 2007年第2期13卷 79-87页

作者：唐洪涛罗纪生周恒 School of Mechanical Engineering Tianjin University

Temporal mode direct numerical simulation was done for the process of laminar-turbulent transition in an incompressible boundary layer on a flat plate. The analysis of the results showed that during the breakdown process of laminar-turbulent transition, the modification of the mean flow profile by the disturbances led to a remarkable change in its stability characteristics, manifested in the significant enlargement of the linear unstable zone and the maximum amplification rate, and led to that many more disturbances were excited and enhanced rapidly, correspondingly the turbulent energy also increased rapidly, and the mean flow profiles evolved swiftly from laminar to turbulent. It was also found that if the oblique waves in the initial disturbances did not form symmetrical pairs, the subsequent span-wise mean velocities would, in general, be nonzero due to nonlinear interaction, which would have a great effect on the stability characteristics and also implied that the turbulence obtained by direct numerical simulation might not be fully a random process.

关键词： boundary layer transition direct numerical simulation breakdown

Inherent mechanism of breakdown in laminar-turbulent transition of plane channel flows

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Science china(Physics,Mechanics & Astronomy) 2005年第2期48卷 228-236页

作者： LUO Jisheng, WANG Xinjun & ZHOU Heng Department of Mechanics, tianjin University liu-{2. center of mathematics, nankai and tianjin University, tianjin 300071, china Department of Mechanics Tianjin University Tianjin 300071 China liu-hui {2. of mathematics Nankai and Tianjin University Tianjin 300071 China

Laminar-turbulent transition is an old yet unsolved problem. Notwithstanding the great effort made, there is an important question that seems not to have been addressed yet, that is, what is the inherent mechanism of breakdown that eventually leads to transition? The conventional idea is that the transition starts from the amplification of disturbances, and when the disturbances become larger, higher harmonics will be generated due to nonlinear effect, making the flow more and more complicated, and finally turbulent. Though the scenario seems clear, yet there is a missing link, that is, what happens in the breakdown process. Here we show by analyzing the results from direct numerical simulations that the change of stability characteristics of the mean flow profile plays a key role in the breakdown process.

关键词： laminar-turbulent transition, breakdown, plane channel flow.

Analysis of regulatory architectures in BST

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Progress in Natural Science:Materials International 2003年第12期 34-39页

作者： BIAN Fuping 1,2. *, LIANG Min 1,2. and ZHAO Xueming 3(1. Department of mathematics, School of Science, tianjin University 2. {2. hui center for applied mathematics, nankai University & tianjin University 3. School of Chemical Engineering, tianjin University, tianjin 300072. china) Department of mathematics，School of Science，tianjin University liu hui {2. for applied mathematics，nankai University & tianjin University School of Chemical Engineering，tianjin University，tianjin {2.china

Based on the data envelopment analysis (DEA) theory, the optimal pathway of metabolic reaction networks in biochemical systems is studied. After calculating the mixed integer linear programming (MILP) model given by Bailey et al. twice, the decision making units (DMU) and the prediction model of DEA are constructed, where the inputs are levels of manipulated parameters (enzyme) and outputs are concentrations of metabolites. When the metabolic networks are reconstructed, the data are obtained by calculating MILP framework twice and the optimal levels of the manipulated parameter at different regular loops are predicted, thus simplifying the calculations of Bailey’s.

关键词： metabolic reaction networks MILP the prediction model of DEA efficient DMU.

Composition operators between p-Bloch space and q-Bloch space in the unit ball

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Progress in Natural Science:Materials International 2003年第3期 75-78页

作者： ZHOU Zehua and ZENG Honggang (1. Department of mathematics, tianjin University,{2. 2. liu hui center for applied mathematics, nankai Uni-versity and tianjin University,{2.) Department of mathematics Tianjin University Tianjin 300072 China liu hui {2. for applied mathematics Nankai University and Tianjin University Tianjin 300072 China

Let B_n be the unit ball of C~n and φ= （φ1,…,φ_n） a holomorphic self-map of B_n. The main purpose of this paper is todiscuss the boundedness and compactness of composition operator Cφbetween p-Bloch space βp（... 详细信息

关键词： p-Bloch space automorphlsms composition operator.