In this work, a passive flow control study is proposed in order to regularize the flow dynamics around a hemisphere at a low and a higher Reynolds number in the wake transition regime. This passive control is realized by covering the projected curved surface of the hemisphere with a porous coating. The presence of such porous medium modifies the boundary conditions at the body-fluid interface, allowing a non-zero velocity to settle in this region. This phenomenon smoothes the global flow dynamics and leads, in particular, to a decrease of the energy dissipation and the aerodynamic force. In this paper, the flow control study is carried out for several configurations using a vortex-penalization technique which allows to easily model solid-fluid-porous media without prescribing any boundary condition.