检索结果-南通市图书馆

The mechanism of breakdown in laminar-turbulent transition of a supersonic boundary layer on a flat plate-temporal mode

在线全文

学校读者我要写书评

暂无评论

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,{2., china 2. Liu-Hui Center of Applied Mathematics, Nankai university and tianjin university,{2., china department of Mechanics Tianjin University Tianjin China Liu-Hui Center of Applied Mathematics Nankai University and Tianjin University 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.

Views on “Principle of limitation of physical quantities and cyclic universe”

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2010年第9期53卷 1772-1774页

作者： LI LianGang department of physics,School of Sciences,{2. university,{2. 3.0072,china department of physics School of Sciences Tianjin University Tianjin China

This paper presents an analysis of a paper entitled "Principle of limitation of physical quantities and cyclic universe" and proposes different results for some formulae from that *** addition,this paper shows that the principle of limits coupling may lead to an approximation of current theories(i.e.,quantum theory and relativistic theory),which have interesting correlations with the Plank formula and the special theory of relativity.

关键词： principle of limitation of physical quantities limits coupling formulae Plank formula theory of relativity

Tunneling Through Black Rings

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical physics 2007年第5期47卷 835-842页

作者： ZHAO Liu department of physics,Nankai {2.,tianjin 300071,china department of physics Nankai University Tianjin 300071 China

Hawking radiation of black ring solutions to 5-dimensional Einstein-Maxwell-dilaton theory is analyzedby use of the Parikh-Wilczek tunneling *** get the correct tunneling amplitude and emission rate,we adoptand develop the Angheben-Nadalini-Vanzo-Zerbini covariant approach to cover the effects of rotation and electronicdischarge all at once,and the effect of back reaction is also taken into *** constitutes a unified approach tothe tunneling *** the first law of thermodynamics for black rings holds,the emission rate is proportionalto the exponential of the change of Bekenstein-Hawking *** calculation for black ring temperatures agreesexactly with the results obtained via the classical surface gravity method and the quasi-local formalism.

关键词： black ring radiation tunneling method

Principle of limitation of physical quantities and cyclic universe

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2008年第5期51卷 451-458页

作者： HE GuoZhu department of physics,Nankai {2.,tianjin 300071,china department of physics Nankai University Tianjin China

A close study of Heisenberg uncertainty principles reveals many significant facts,and all four major physical quantities,energy,time,momentum and length,have both lower and upper ***,many questions come *** are these limits?Some answers may lead to the understanding of the development of our *** is the shortest limit of time?At the beginning of big bang,there exists a tre-mendously short time,the Planck *** may be just the shortest time limit in our *** longest time limit might be the lifetime of our *** longest length might be the final diameter of our expanding *** these lead to a finite *** more coupling formulae are formed for the other two pairs of physical quantities,mass and speed,thermal energy and *** four physical quantities must also have *** already knew that speed has upper limit and temperature has lower *** these two formulae,Planck and Einstein equations are derived *** most other physical quantities are somewhat related to these major physical quantities,it seems that there exists a principle of limitation of physical quantities.A quantitative sketch of big bang is *** also shows that our universe will contract back to another big *** principle of limitation opens up some fields of *** may bring nature back to the harmony and determined world described by classical physics.

关键词： principle of limitation of physical quantities limits coupling formulae cyclic universe extension of conven-tional quantum mechanics no uncertainty for physical quantities quantitative evaluation of big bang

Low－Temperature　Spectral　Properties　and　Zero－Phonon　Transitions　of　Alkali　Halide　Crystal　Materials　Bombarded　with　Electrons　and　Implanted　with　Ions

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Lasers 1995年第2期B4卷 111-116页

作者： GU Hongen(department of Applied physics,{2., tianjin 3.0072, china) tianjin Univ Tianjin China

Ｌｏｗ－ＴｅｍｐｅｒａｔｕｒｅＳｐｅｃｔｒａｌＰｒｏｐｅｒｔｉｅｓａｎｄＺｅｒｏ－ＰｈｏｎｏｎＴｒａｎｓｉｔｉｏｎｓｏｆＡｌｋａｌｉＨａｌｉｄｅＣｒｙｓｔａｌＭａｔｅｒｉａｌｓＢｏｍｂａｒｄｅｄｗｉｔｈＥｌｅｃｔｒｏ... 详细信息

Ｌｏｗ－ＴｅｍｐｅｒａｔｕｒｅＳｐｅｃｔｒａｌＰｒｏｐｅｒｔｉｅｓａｎｄＺｅｒｏ－ＰｈｏｎｏｎＴｒａｎｓｉｔｉｏｎｓｏｆＡｌｋａｌｉＨａｌｉｄｅＣｒｙｓｔａｌＭａｔｅｒｉａｌｓＢｏｍｂａｒｄｅｄｗｉｔｈＥｌｅｃｔｒｏｎｓａｎｄＩｍｐｌａｎｔｅｄｗｉｔ...

关键词： zero-phonon transition. color centers

Low-temperature optical spectra and zero-phonon transition of color centers in γ-rayed lithium fluoride crystals

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Lasers 1993年第5期B2卷 59-63页

作者： Honggen Gu (department of physics,{2., tianjin 3.0072,china) tianjin Univ Tianjin China

The zero-phonon lines on R2. R~+, N1and R′2.enters and some new narrow lines have been observed in bivalent-metal-doped and air-grown LiF crystals irradiated by γ-ray in the temperature range of 9.5—130K. The spect... 详细信息

关键词： low-temperature spectra zero-phonon transition color-centers in LiF2

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

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

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,{2., china 2. Liu-Hui Center of Applied Mathematics, Nankai university and tianjin university,{2., china department of Mechanics Tianjin University Tianjin China Liu-Hui Center of Applied Mathematics Nankai University and Tianjin University 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.

A combined numerical model of three-dimensional tidal motion and sediment transport in tidal current and its application

在线全文

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2000年第1期19卷 145-154页

作者： Dong Wenjun Bai Yuchuan Li Shisen (1. department of Mathematics, tianjin university,{2., china 2. department of Hydraulics, tianjin university,{2., china) department of Mathematics Tianjin University Tianjin 300072 China department of Hydraulics Tianjin University Tianjin 300072 China

A calculation scheme, which combines a horizontal upwind finite element method with vertical implicit differences, is used to establish a three-dimensional mathematical model of tidal motion and sediment transport in tidal current. Compared with those of the relative theoretical formula, the results are satisfactory. The model mentioned above has been applied to the water area of the Lianzhou Bay, Guangxi Province. On the basis of the analysis and comparison with the field data, it shows clearly that the model calculation results are reasonable.

关键词： Tidal current sediment transport in tidal current upwind finite element three- dimensional numerical simulation

The reliability of the improved e^N method for the transition prediction of boundary layers on a flat plate

在线全文

学校读者我要写书评

暂无评论

Science china(physics,Mechanics & Astronomy) 2012年第5期55卷 837-843页

作者： SU CaiHong1,2.1 department of Mechanics,tianjin {2.,tianjin 3.0072,china 2.tianjin Key Laboratory of Modern Engineering Mechanics,tianjin 3.0072,china department of Mechanics Tianjin University Tianjin China tianjin Key Laboratory of Modern Engineering Mechanics Tianjin China

The transition criterion in the improved eN method is that transition would occur whenever the velocity amplitude of disturbance reaches 1%-2. of the free stream velocity,while in the conventional eN method,the N factor is an empirical *** this paper the reliability of this key assumption in the improved eN method is checked by results of transition prediction by using the Parabolized Stability Equations(PSE).Transition locations of an incompressible boundary layer and a hypersonic boundary layer at Mach number 6 on a flat plate are predicted by both the improved eN method and the PSE *** from both methods agree fairly well with each other,implying that the transition criterion proposed in the improved eN method is reliable.

关键词： transition prediction boundary layer eN PSE