  We study in this work steady laminar flows in a low density granular gas
modelled as a system of identical smooth hard spheres that collide
inelastically. The system is excited by shear and temperature sources at the
boundaries, which consist of two infinite parallel walls. Thus, the geometry of
the system is the same that yields the planar Fourier and Couette flows in
standard gases. We show that it is possible to describe the steady granular
flows in this system, even at large inelasticities, by means of a
(non-Newtonian) hydrodynamic approach. All five types of Couette-Fourier
granular flows are systematically described, identifying the different types of
hydrodynamic profiles. Excellent agreement is found between our classification
of flows and simulation results. Also, we obtain the corresponding non-linear
transport coefficients by following three independent and complementary
methods: (1) an analytical solution obtained from Grad's 13-moment method
applied to the inelastic Boltzmann equation, (2) a numerical solution of the
inelastic Boltzmann equation obtained by means of the direct simulation Monte
Carlo method and (3) event-driven molecular dynamics simulations. We find that,
while Grad's theory does not describe quantitatively well all transport
coefficients, the three procedures yield the same general classification of
planar Couette-Fourier flows for the granular gas
