DNS of particle dispersion in a spatially developing turbulent boundary layer

We performed DNS of particle-laden spatially developing turbulent boundary layer at Re$_\theta=1000-3200$. We computed the Lagrangian trajectories of millions of fluid points and solid particles of three different Stokes number, St=0.1, 1, and 5. The particles were gradually released from a line source. We computed the time development of particle mean displacement, dispersion, and turbulent diffusivity. Our DNS results of fluid point mean-displacements are in excellent agreement with those of Batchelor's (1964) theory. Also, our DNS results show that in general particle statistics are strongly influenced by particle's Stokes number. Such dependence is mostly caused by the particles tendency to preferentially accumulate in the viscous sublayer as their Stokes number increases. Furthermore, for $t/T_L<1$ where $T_L$ is the Lagrangian integral time scale, the streamwise and wall-normal dispersions are $\propto t^{2}$ for fluid points and $\propto t^{3}$ for solid particles. For $20