Before revision:  After extending the stabilization procedure of  [ 17 ] to incompressible flow problems, we theoretically prove that, combined with the Raviart-Thomas isogeometric element , we are able to recover the well-posedness of the formulation and, consequently, optimal a priori error estimates.
After revision:  After extending the stabilization procedure of [ 16 ] to incompressible flow problems, we theoretically prove that, combined with the Raviart-Thomas isogeometric element , we are able to recover the well-posedness of the formulation and, consequently, optimal a priori error estimates.