Propagation of a smoke in a closed 3D room. A source of the smoke is situated on one of the vertical walls. It is modelled as a small spot on the wall with predefined permanent high temperature and concentration. Under influence of a thermo-gravitational convection the smoke propagates and fills the room. The picture shows evolution of smoke concentration in central cross-section of the room. 3D view of the same problem is presented in the GIF animation "fier2". The task is described in details in technical report on "Research in Brussels" grant in 1999. Code ASTRA.