The purpose of this study report is to examine the unsteady force convection flow on irregular boundary over a diverging channel with effect of viscous dissipation. The fundamental equations of fluid, continuity, momentum, and energy equations are converted into dimensionless form. The resulting coupled partial differential equations are linearized by quasilinearization technique, the backward, and central difference scheme for nonuniform mesh used to solve the system of linear equations. We found that finite difference scheme for nonuniform mesh gives smoothness of solution compared to finite difference scheme for uniform mesh on irregular boundary, this is evident from Figure 2. Near the wall region, as viscous dissipation (Ec) increases from 0.2 to 0.5, the temperature profiles overshoots 20% to 112%. Also the effects of Reynolds number (Re) on heat transfer coefficient is comparatively less than skin-friction coefficient. © 2020 Wiley Periodicals LLC