Three primitive-variable formulations used on nonstaggered grids have been developed and examined. For comparison and assessment, an internally heated rectangular-elbow flow problem whose exact solution exists and is known is introduced. The characteristics of the three formulations depend on how the continuity constraint is incorporated. If the continuity equation is directly used, the resulting matrix is solved by a direct matrix solver. If the pressure Poisson equation is used or if the nodal velocities in the continuity are substituted for nodal pressures, an iterative scheme such as the Gauss-Seidel method can be used. These formulations must be modified slightly when inhomogeneous Neumann boundary conditions are imposed. On the basis of the computed solution, it is recommended that the formulation using the pressure substitution be used in conjunction with second-order accurate discretized momentum equation applied to the boundary.