Estimates of deviations from exact solution of the Stokes problem in the vorticity-velocity-pressure formulation

Vorticity-velocity-pressure formulation for the stationary Stokes problem in 2D is considered. We analyze the corresponding generalized formulation, establish sufficient conditions that guarantee existence of the generalized solution and deduce estimates of the difference between the exact solution (i.e., exact velocity, vorticity, and pressure) and an arbitrary approximating function (velocity, vorticity, pressure) that belongs to the corresponding functional class and satisfies the boundary conditions. For this purpose we use the method suggested in [10, 12], which is based on transformations of the integral identity that defines the corresponding generalized solution.