Instabilities of dislocations in fluid patterns

Dislocations are important for wave-number adjustment in the almost periodic patterns found in convecting fluids and a wide variety of other physical contexts. Using a model for infinite-Prandtl-number fluids, we show that, far from onset, climbing dislocations can undergo local, finite-amplitude instabilities that lead to the formation of disclinations, bridgelike structures, sudden roll disappearance, and gliding.