Spontaneous flow in polar active fluids: the effect of a phenomenological self propulsion-like termFrancesco Bonelli, Giuseppe Gonnella, Adriano Tiribocchi and Davide MarenduzzoEur. Phys. J. E, 39 1 (2016) 1DOI: https://doi.org/10.1140/epje/i2016-16001-2