Abstract
As a preliminary step for understanding the cloud micro physics, an efficient direct numerical simulation code for tracking a large number of small inertial particles which are convected by isotropic turbulence has been developed. Three dimensional FFT for the spectral method is constructed by using two dimensional domain decomposition and MPI, and the effective domain decomposition is explored. Under the action of the gravity and turbulence the equations of motion of a large number of particles are integrated and their spatial distribution is studied by changing the Stokes numbers.
