EFFECT OF WIND SHEAR ON THE FILM THICKNESS DISTRIBUTION OVER ROTATINGDOUGHNUT DISKS

Spin coating has been extensively investigated. However, a numerical s tudy of the wind shear effect on film thickness distributions over dou ghnut disks has not yet been performed. Also, the effect of a hub on t he air shear flow over a rotating doughnut disk has not yet been addre ssed. In this study, we predict successive liquid surface contours on rotating doughnut disks. The results are compared with experimental da ta, and discrepancies between them are identified. We found that the d iscrepancies are caused mainly by the presence of a hub, and that the wind shear effect cannot be simply analyzed in terms of Cochran's solu tion.