BIRS Workshop Lecture Videos

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BIRS Workshop Lecture Videos

Drag Closure for Fluid-particle flows in Fluidized Beds Sundaresan, Sankaran


Talk: Plenary Abstract: Fluidized suspensions of particles manifest inhomogeneities spanning a wide range of length and time scales. Our research examines how one could capture the effects of these inhomogeneities on fluid-particle drag force. To probe this, we have performed simulations of flows at different scales: (a) at the particle-scale through Lattice-Boltzmann simulations; (b) at a larger scale through Euler-Lagrange Simulations tracking collisions between particles through Discrete Element Method, and (c) at an even larger scale through two-fluid model simulations. Snapshots generated through these simulations are analyzed to identify the pattern of dependence of the drag force on inhomogeneities that persist at all scales. It is found that the drag force model should include dependence on particle Stokes number and the local mean-squared fluctuations in the particle volume fraction occurring at a scale smaller than the filter scale. A dynamic, scale-similar model is proposed for the local mean-squared fluctuations in the particle volume fraction, which would not be available in coarse simulations. This improved model should lead to higher-fidelity simulations, thus enabling innovations to be tested initially through simulations before engaging in costly experimental testing.

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