Abstract: The invention relates to a method providing mixing of at least one gaseous fluid in the combustion chamber of a direct-injection internal-combustion engine comprising at least a cylinder (10), a cylinder head (12), a piston (22) sliding in this cylinder, a fuel-injection nozzle (24), a combustion chamber delimited on one side by the upper face of piston (22) comprising a teat (30) pointing towards cylinder head (12) and arranged in a concave bowl (28), and intake means (14, 16) for at least one gaseous fluid, said intake means being designed so as to admit the gaseous fluid into the combustion chamber with a swirling motion or swirl.