Interaction of oblique dark solitons in two-dimensional supersonic   nonlinear Schr\"odinger flow
  We investigate the collision of two oblique dark solitons in the two dimensional supersonic nonlinear Schr\"odinger flow past two impenetrable obstacles. We numerically show that this collision is very similar to the dark soliton collisions in the one dimensional case. We observe that it is practically elastic and we measure the shifts of the solitons positions after their interaction. 
E. S. Annibale and A. Gammal
nlin.PS cond-mat.quant-gas