Finger breakup in Hele–Shaw cells

Abstract
It is shown that a boundary integral simulation of fingering in Hele–Shaw cells generates patterns of finger breakup similar to those observed experimentally at low values of reciprocal capillary number τ. It is also shown that, when random noise is introduced in the interface position at a value of τ for which a stable finger would otherwise occur, similar patterns of finger breakup are generated. This supports the hypothesis that the observed behavior is caused by a nonlinear instability driven by experimental or numerical noise at very low values of τ.