"Flying Particles" flow

The following examples concern flow in a chamber with moving particles of different size.

The aim of the following simulations is just to demonstrate the utility of our "Fictitious Boundary Conditions": All calculations are performed on ONE SINGLE mesh which does not change! The position of the actual boundary is determined via "filters" and incorporated into the iterative solvers! A more detailed description of the underlying mathematical and numerical concepts is given in Stefan Turek's CFD-book, Springer.

The "true" complexity of the physical problem depends on the:

• size and speed of the particles
• path of the particles ("collision")
• boundary conditions

While in reality the particles will change their flow behaviour if they approach one another - up to a collision!!! - we allow in the following simulations the "nonphysical" event that two or even several particles build one single "macro-particle" - for a short lifetime! To be concrete: we neglect all implicit behaviour but we prescribe instead a fixed motion of the particles. As pointed out, these tests are for a demonstration of the "Fictitious Boundary Conditions" only while the physical interactions can be added by users who are interested in this topic!

• "Flying Particles" at low Reynolds number ("Natural boundary conditions" at the walls)
• "Flying Particles" at medium Reynolds number ("Dirichlet boundary conditions" at the walls)