On the impact of controlled wall roughness shape on the flow of a soft material F. Pelusi, M. Sbragaglia, A. Scagliarini, M. Lulli, M. Bernaschi and S. Succi EPL, 127 3 (2019) 34005 Published online: 19 September 2019 DOI: 10.1209/0295-5075/127/34005