THE AXISYMMETRICAL MOTION OF A LIQUID-FILM ON AN UNSTEADY STRETCHING SURFACE

The axisymmetric motion of a fluid caused by an unsteady stretching su rface that has relevance in extrusion process and bioengineering has b een investigated. It has been shown that if the unsteady stretching ve locity is prescribed by rb/(1-alpha t), then the problem admits a simi larity solution which gives much insight to the character of solutions . The asymptotic and numerical solutions are obtained and they could b e used in the testing of computer codes or analytical models of more r ealistic engineering systems. The results are governed by a nondimensi onal unsteady parameter S and it has been observed that no similarity solutions exist for S > 4.