Thermal effects on film development during spin coating

This study is an extended version of a previous analysis of thermal effects on the free-surface liquid film flow on a flat, heated rotating disk [A. Kitamura, Thermal effects of liquid film flow during spin coating, Phys. Fluids 13, 2788 (2001)]. The assumption of a constant disk temperature is extended to a nonuniform disk temperature, and the restriction on small radial distance used in the previous analysis is removed. The evolution equation for the transient film thickness is obtained and solved by the method of characteristics [B. S. Dandapat, P. Daripa, and P. C. Ray, Asymptotic study of film thinning process on a spinning annular disk, J. Appl. Phys. 94, 4144 (2003)]. The effect of both thermocapillary forces and variable viscosity on the flow is revealed. A physical explanation is provided to justify the results. (c) 2005 American Institute of Physics.