These are a few wave patterns that I generated using ANSYS macros which are attached. I will post more pictures when I print them at high res. I may also add patterns from time to time. p.s. the math has been adjusted to avoid the theoretically infinite spike at the center. In a real rain drop, the inward rushing wave at the center causes a "backjet" or spike in the center. I am guessing that the spike height in a raindrop is limited by surface tension and viscosity of the water and other small effects.