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In this tutorial, we study a case of particle laden flows. The purpose is to illustrate some of the complex interactions between the fluid phase and a dispersed particle phase using commercially available tools. For this purpose, we study a 2D-periodic double shear layer with disceminated particles disseminated particles as shown bellow:

Figure 1. Initial setup for the problem.

In the absence of any perturbation, a mixing layer, for instance a Ux = U tanh(y) profile, diffuses under the action of viscosity to the mean value of top and bottom velocities. On the other hand, specially manufactured oscillations in the shearing layers will lead to the evolution of vorticies. These perturbations must satisfy the Orr-Sommerfeld equation, otherwise they are suppressed by viscosity. In this tutorial we provide the initial flow condition containing the Orr-Sommerfeld perturbation in a separate input file.

The point of having vorticies develop in the flow field, is to observe the interaction of particles with these structures. In a general sense, "light" particles get trapped in flow vorticies, while "heavier" particles carrying more inertia might get expelled under a corriolis-type effect from the swirling regions to gather along stretching regions of the flow. This effect is known as preferential concentration and is illustrated in the following sketch:[Insert preferential concentration sketch]

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Figure 2. Preferential concentration mechanism: particles gather along stretching regions and get expelled from vortical regions.

Formal definitions, and a thorough discussion is provided in the Pre-Analysis section.

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