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μ(I) Rheology
In granular mechanics, the ''μ(I)'' rheology is one model of the rheology of a granular flow. Details The inertial number of a granular flow is a dimensionless quantity defined as I = \frac, where \dot\gamma is the shear rate tensor, , , \dot\gamma, , is its magnitude, ''d'' is the average particle diameter, ''P'' is the isotropic pressure and ''ρ'' is the density. It is a local quantity and may take different values at different locations in the flow. The ''μ''(''I'') rheology asserts a constitutive relationship between the stress tensor of the flow and the rate of strain tensor: \sigma_ = -P\delta_ + \mu(I)P \frac where the eponymous ''μ''(''I'') is a dimensionless function of ''I''. As with Newtonian fluids, the first term -''Pδ''''ij'' represents the effect of pressure. The second term represents a shear stress: it acts in the direction of the shear, and its magnitude is equal to the pressure multiplied by a coefficient of friction ''μ''(''I''). Thi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Granular Mechanics
A granular material is a conglomeration of discrete solid, macroscopic particles characterized by a loss of energy whenever the particles interact (the most common example would be friction when grains collide). The constituents that compose granular material are large enough such that they are not subject to thermal motion fluctuations. Thus, the lower size limit for grains in granular material is about 1 μm. On the upper size limit, the physics of granular materials may be applied to ice floes where the individual grains are icebergs and to asteroid belts of the Solar System with individual grains being asteroids. Some examples of granular materials are snow, nuts, coal, sand, rice, coffee, corn flakes, fertilizer, and bearing balls. Research into granular materials is thus directly applicable and goes back at least to Charles-Augustin de Coulomb, whose law of friction was originally stated for granular materials. Granular materials are commercially important in applic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
