Considering that without diffusion, no mixing would take place, it might be possible to drop the advection term of eq 1 altogether in the context of multi-impeller equipment and allow the diffusion term to model all forms of transport (advection, turbulent dispersion, molecular diffusion). Such a simplification would result in an analytically soluble macromixing model that might fit experimental tracer data and give insight on how the tank's geometry and the number and placement of feed points affect the macromixing time-scale. Mere diffusion as a model of mixing is similar to the classical 1D dispersioncirculation model , in which the concentration's homogenization is ultimately driven solely by the diffusive process, the dispersion. Compartment models, which are essentially discretizations of eq 1 , also rely on diffusion-like exchange flows, and likewise most CFD simulations model the gradient-smoothing effects of turbulence with turbulent diffusivity.