During phase transition from the liquid-expanded to the liquid-condensed state, a dispersed Langmuir film of pentadecanoic acid is submitted to an annular shear flow of moderate Reynolds number ͑Re= 10-100͒. The mesoscopic morphology of this two-phase Langmuir film is investigated based on area fraction distribution of the condensed phase after a permanent regime is established. The distribution demonstrates radially inwards packing along the liquid surface induced by centripetal flow originating from centrifugation of the subphase along the rotating floor. For a growing level of centrifugation, a circular Reynolds ridge arises along the liquid surface. The Langmuir film experiences a strong morphological transition driven by a balance between surface shear and reduced line tension. As a result, a shear-induced melting of the condensed domains generates a new patterning which can be described as a regular and monodispersed matrix of tiny condensed droplets.

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