“…It is one of the most challenging and least understood aspects of bubble dynamics (Magnaudet and Eames, 2000). Many researchers have investigated experimentally and numerically the path instability of bubbles (Haberman and Morton, 1954;Saffman, 1956;Aybers and Tapucu, 1969;Wegener and Parlange, 1973;Mougin and Magnaudet, 2002;Mougin and Magnaudet, 2006;Brenn et al, 2006;Yang and Prosperetti, 2007;Zenit and Magnaudet, 2008;Fernandes et al, 2008;Adoua et al, 2009, Hassan et al, 2010a. Many investigators (Haberman and Morton, 1954;Saffman, 1956;Aybers and Tapucu, 1969;Duineveld, 1994Duineveld, , 1995Maxworthy, 1996;de Vries, 2001;de Vries et al, 2002) indicated that the onset of path instability of a bubble is in general occurring at different stages, and the condition for bubble deformation is that We must exceed a critical value ( > cr We We ).…”