We construct a finite volume element method based on the constrained
nonconforming rotated Q1-constant element (CNRQ1-P0) for the Stokes problem.
Two meshes are needed, which are the primal mesh and the dual mesh. We approximate
the velocity by CNRQ1 elements and the pressure by piecewise constants.
The errors for the velocity in the H1 norm and for the pressure in the L2 norm are
O(h) and the error for the velocity in the L
2 norm is O(h2). Numerical experiments
are presented to support our theoretical results.