[Shabi]

Consider a simple 2D channel where the flow enters the domain from one side with the inlet velocity boundary condition with a constant value and it forms a boundary layer.

1) If i add many number of particles consistently to the inlet and neglect all inertial forces and let it to follow the flow trajectories, is there any difference if my particles are massless, or if they are neutral buoyant?

2) If the particles is going to follow the flow trajectories, is it true that the volume fraction of the particle in the domain (C) is the solution of the advection equation, dC/dt + div (vC) = 0? If so,

3) If the inlet boundary condition for C is the constant value of 1, we know that in the steady state whole domain will be filled with the uniform value of C=1. But, it contradicts with what we expect with the particle case. Because if we add particles to the inlet consistently, because of the boundary layer, we expect a non-uniform value for the volume fraction in the steady state, because it is not possible to have a uniform distribution of particles in the domain in the steady state.

Thank you in advance for sharing your ideas.