The Navier-Stokes equations of the vorticity-stream-function form are solved numerically for the flow past a semicircular arc for Reynolds numbers in the range 0.1<Re<50. Two special cases are treated: Firstly, the convex side of the arc is facing the flow(convex flow)and, secondly, the concave side(concave flow). The details of the flow structure, i.e. the streamlines, vorticity distributions, eddy dimensions, and the separation points are presented and discussed for the various Reynolds numbers. The convex flow is similar to that of the circular cylinder while the concave flow exhibits the characteristics of the flow past a normal plate. Comparisons of the present results with other available bluff-body results are also made when they are appropriate.