List of files:

dns_results contains statistical results of the fluid velocity

dns_particles_1, dns_particles_5 and dns_particles_25 contain
statistical results of particle velocity and fluid velocity at
particle position for the three Stokes numbers

concentration contains particle concentration profiles at two
different times at a better resolution.

The numerical method is as follows:
 
Fourier-Galerkin method in the streamwise and spanwise directions
Chebyshev-collocation method in the wall-normal direction.
Nonlinear terms are calculated in a pseudo-spectral way with
de-aliasing in the periodic directions.
The solution is completely divergence-free through the use of the
influence matrix method.
Time integration is performed with a third-order three-stage
Runge-Kutta method for the nonlinear terms and the implicit
Crank-Nicolson method for the linear terms.
The particle equation of motion is solved with the second-order
Heun method. 
Fluid velocity at particle position is found by fourth-order accurate
interpolation: Lagrange in periodic directions and Hermite in
wall-normal direction.
Particles bounce elastically with the walls.

The domain size is 4*pi*delta in x, 2*delta in y, and 2*pi*delta in z
where delta is the halfwidth.

Grid size is: 128x129x128
Number of particles is: 100,000

Stokes numbers are: 1, 5, 25
Shear Reynolds number is: 150 based on Re_tau