Yimin Jiang

Bio: Yimin Jiang is an academic researcher from Central South University. The author has contributed to research in topics: Granular material & Constitutive equation. The author has an hindex of 17, co-authored 45 publications receiving 850 citations. Previous affiliations of Yimin Jiang include University of Tübingen.

Granular solid hydrodynamics

Abstract: A complete continuum mechanical theory for granular media, including explicit expressions for the energy current and the entropy production, is derived and explained. Its underlying notion is: granular media are elastic when at rest, but turn transiently elastic when the grains are agitated—such as by tapping or shearing. The theory includes the true temperature as a variable, and employs in addition a granular temperature to quantify the extent of agitation. A free energy expression is provided that contains the full jamming phase diagram, in the space spanned by pressure, shear stress, density and granular temperature. We refer to the theory as GSH, for granular solid hydrodynamics. In the static limit, it reduces to granular elasticity, shown previously to yield realistic static stress distributions. For steady-state deformations, it is equivalent to hypoplasticity, a state-of-the-art engineering model.

Granular Solid Hydrodynamics

Abstract: Granular elasticity, an elasticity theory useful for calculating static stress distribution in granular media, is generalized to the dynamic case by including the plastic contribution of the strain. A complete hydrodynamic theory is derived based on the hypothesis that granular medium turns transiently elastic when deformed. This theory includes both the true and the granular temperatures, and employs a free energy expression that encapsulates a full jamming phase diagram, in the space spanned by pressure, shear stress, density and granular temperature. For the special case of stationary granular temperatures, the derived hydrodynamic theory reduces to {\em hypoplasticity}, a state-of-the-art engineering model.

Granular elasticity without the Coulomb condition.

Abstract: A self-contained elastic theory is derived which accounts both for mechanical yield and shear-induced volume dilatancy. Its two essential ingredients are thermodynamic instability and the dependence of the elastic moduli on compression.

From elasticity to hypoplasticity: dynamics of granular solids.

Abstract: "Granular elasticity," useful for calculating static stress distributions in granular media, is generalized by including the effects of slowly moving, deformed grains. The result is a hydrodynamic theory for granular solids that agrees well with models from soil mechanics.

Granular elasticity: stress distributions in silos and under point loads.

Abstract: In elastic media, the energy w =wij is a function of the strain ij, a parametrization of the medium’s deformation. Its derivative yields the stress-strain relation, ij =� w /ij, which is pivotal in closing the force balance, jij= 0, and enables us to determine stress distributions systematically, for any geometry and boundary conditions. In sand, the strain field ij=uij+uij has two parts: the elastic one that accounts for the deformation of the grains, and the plastic one for their irreversible rolling and slippage, with the latter usually dominating. This appears quite unfortunate, because the plastic contribution precludes a unique stress-strain relation, ij=ijk. This is what makes granular stress calculation the notoriously open problem it is. Yet there is no reason whatsoever why one could not take the energy as a function of the elastic strain alone, w =wuij, and the stress as ij =� w /uij, because rolling and slippage obviously cannot give rise to energy storage and maintain static stresses. Doing so offers a mechanical solution to the plastic impasse, because given an appropriate expression for the granular elastic energy w, we can use the associated stress, ij=ijuk, as an elastic-strain–stress relation, for closing the force balance, jij= 0. This implies we can determine granular stress distributions just as systematically we do in elastic media. This approach, christened granular elasticity GE, was introduced in Ref. 9 and explained in detail in the preceding paper 3. Here, we employ it to calculate the stress distribution in silos and under point loads.

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Proceedings of the National Academy of Sciences

Abstract: where A represents the magnetic vector potential, is an integral of the hydromagnetic equations. This -integral made it possible to formulate a variational principle for the force-free magnetic fields. The integral expresses the fact that motions cannot transform a given field in an entirely arbitrary different field, if the conductivity of the medium isconsidered infinite. In this paper we shall show that the full set of hydromagnetic equations admit five more integrals, besides the energy integral, if dissipative processes are absent. These integrals, as we shall presently verify, are I2 =fbHvdV, (2)

Journal of Fluid Mechanics创刊50周年

Abstract: 流体力学杂志“Journal of Fluid Mechanics”由剑桥大学教授George Batchelor在1956年5月创办，在国际流体力学界享有很高的学术声望，被公认为是流体力学最著名的学术刊物之一，2005年的影响因子为2．061，雄居同类期刊之首．在它创刊50周年之际，2006年5月JFM出版了第554卷的纪念特刊，其中刊登了现任主编（美国西北大学S．H．Davis教授和英国剑桥大学T．J．Pedley教授）合写的述评：“Editorial：JFM at50”，以JFM为背景，从独特的视角对近50年来流体力学的发展进行了简明的回顾和展望，并归纳了一系列非常有启发性的有趣统计数字．2006年7月21日在剑桥大学应用数学和理论物理研究所（DAMTP）举行了创刊50周年的庆祝会．下午2点，JFM的新老编辑和来宾会聚一堂，Pedley教授致开幕词，其后是5个精彩的报告：The mysterious rattleback and its fluid counterpart（Keith Moffatt），Developments in shear instabilities（Patrick Huerre），Falling clouds（Elisabeth Guazzelli），Ecotectural fluid mechanics（Paul Linden），The success of JFM（Herbert Huppert），最后由Davis教授致闭幕词．

Non-Equilibrium Thermodynamics

Abstract: In the preceding chapters with few exceptions we studied systems at equilibrium. This means that the systems do not change or evolve over time.