Methods and systems are provided for an exhaust gas aftertreatment mixing assembly. In one example, the mixing assembly includes an injector and a helical blade. The injector may be positioned relative to the helical blade with an orientation that augments entrainment and dispersion of a diesel exhaust fluid into an exhaust gas stream and the helical blade may be configured to increase an exhaust gas flow path while maintaining a compact size of the mixing assembly. Geometries of the injector and the helical blade together may increase decomposition of a diesel exhaust fluid to facilitate enhanced reduction of nitrous oxides in exhaust gases.