Deep reinforcement learning for turbulent drag reduction in channel flows Luca Guastoni, Jean Rabault, Philipp Schlatter, Hossein Azizpour and Ricardo Vinuesa Eur. Phys. J. E, 46 4 (2023) 27 Published online: 11 April 2023 DOI: 10.1140/epje/s10189-023-00285-8