In certain boundary layer or natural convection work, where a similarity transformation is valid, the equations can be reduced to a set of nonlinear ordinary differential equations. They are therefore well-suited to a fast solution on an analog/hybrid computer. This paper illustrates such usage of the analog/hybrid computer by a set of applications of increasing complexity. The examples chosen are the growth of the boundary layer as expressed by the Blasius equation, the steady natural convection plume above a horizontal line heat source, and free convection from horizontal surfaces. The analog computer is effective in both educational and research contexts providing very rapid solutions to such problems. (Author/BB)