Spectral discretization of the Navier–Stokes equations coupled with the heat equation Rahma Agroum, Saloua Mani Aouadi, Christine Bernardi and Jamil Satouri ESAIM: M2AN, 49 3 (2015) 621-639 Published online: 03 April 2015 DOI: 10.1051/m2an/2014049