| We consider the patterns formed by small rod-like objects advected by a random flow in two dimensions. A simple theorem indicates that the their direction field is non-singular. However, we show that singular behaviour can emerge in the long time limit. First, 'flip lines' emerge where the rods abruptly change direction by pi. Later, these flip lines become so narrow that they disappear, but their ends remain as point singularities. These point singularities are of the same type as those seen in fingerprints. |
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