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Publications [#60207] of Peter K. Haff

Papers Published

  1. Haff, P.K., Grain flow as a fluid-mechanical phenomenon, Journal of Fluid Mechanics, vol. 134 , pp. 401 - 30
    (last updated on 2007/04/10)

    Abstract:
    The behaviour of granular material in motion is studied from a continuum point of view. In so far as possible, individual grains are treated as the `molecules' of a granular `fluid'. Besides the obvious contrast in shape, size and mass, a key difference between true molecules and grains is that collisions of the latter are inevitably inelastic. This, together with the fact that the fluctuation velocity may be comparable to the flow velocity, necessitates explicit incorporation of the energy equation, in addition to the continuity and momentum equations, into the theoretical description. Simple `microscopic' kinetic models are invoked for deriving expressions for the `coefficients' of viscosity, thermal diffusivity and energy absorption due to collisions. The `coefficients' are not constants, but are functions of the local state of the medium, and therefore depend on the local `temperature' and density. In general the resulting equations are nonlinear and coupled. However, in the limit sd, where s is the mean separation between neighbouring grain surfaces and d is a grain diameter, the above equations become linear and can be solved analytically

    Keywords:
    fluid dynamics;


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