Brinkman equation, Brinkmann equations, Hdiv conforming, Nitsche, Nitsche's method, Nitsches method, Robin boundary conditions, SIPG, Stokes problem, a posteriori, a posteriori error estimate, a-posteriori error estimates of the functional type, computations, conforming finite element method, discontinuous Galerkin method, finite volume method, generalized Stoke's problem, guaranteed upper bound, macroelement technique, mixed finite element method, mixed finite element methods, nonconforming finite element method, singularly perturbed, stabilization, unified framework.