Gaussian grooves propagating across a moving curved interface in directional solidification

In gratitude to Antoine Skoulios for original and illuminating insights on complex materials, and, to celebrate the emergence of his new adventures, t his article is a synopsis of astonishing observations made about a decade a go on a deceptively simple material, succinonitrile, during its crystal gro wth from a curved phase boundary traveling in narrow channels. For a range of pulling speeds, v, v(c1) < v < v(c2), the flat interface transforms, fir st, to a curved one, then, to a cellular one by groove propagation. The sha pe of the lead groove is Gaussian, consistent with a linear concentration g radient across the interface, and the pattern has a well-defined wavelength . When v < v(c1), the interface remains flat and when v <greater than> v(c2 ), the pattern is time dependent.