2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/157497A nonlinear differential equation about optimal shapes for blades of a fan. A boundary value differential problem from engineering, geometrical or physical bonds. A relation between linear profiles and constant speed along the side under flow.5 pages, 2 figures, report from R&D Department research - Riello Burners - ItalyClassical Analysis and ODEsMathematical PhysicsFluid Dynamics76G25text