Gas-drag Induced Migration of Solids in the Vicinity of a Density Enhancement in a Non-uniform Solar Nebula

We present the results of an extensive numerical study of the orbital evolution of small solids, ranging from dust grains to km-sized objects, in the vicinity of a local density enhancement in a non-uniform solar nebula. In a previous study we have shown that when the motions of such solids are restricted to the midplane of the nebula, the combined effect of gas drag and pressure gradients causes the solids to radially migrate toward the location of the maximum gas density. In this paper, we extend our previous analysis to three-dimensional cases and show that such migrations can occur along both radial and vertical directions. We also show that for a certain range of solids’ radii, these migrations can be quite rapid. The implications of such rapid migrations for collisional coagulations of small solids and also for enhancement of the growth-rate of planetesimals are also discussed.