Engulfment-deformation-diffusion

Engulfment Deformation Diffusion (EDD) model of Baldyga and Bourne (1984). 

A complete description of micromixing is included in the engulfment-deformation-diffusion model (EDD), Baldyga and Bourne (1986). 

Different mixing models such as the lEM (interexchange with the mean) model [67], the droplet erosion and diffusion model [68], the engulfment deformation diffusion model and the engulfment model [69, 70], and the incorporation model [71] have been proposed. 

There are other more advanced micro-mixing models such as the engulfment, deformation, and diffusion (EDD) model [24-26] and the interaction by exchange with the mean (lEM) model [27], The reader should consult the original papers for details. 

Micromixing is realized by an unsteady molecular diffusion within deforming slabs or laminar structures, which are embedded within energy dissipating vortices (Baldyga and Bourne 1986), and it is assumed to be controlled by the fluid engulfment. 

Applications of this description of micromixing requires integration of equations like (10.16), which can become a substantial numerical task ". Provided, however. Sc 4000, deformation and diffusion can be neglected the important step in micromixing is then the rate of formation of fine-scale vortices by engulf-... 

The micro-mixing time may be equal to the diffusion time needed to equalize concentrations on the scale of the smallest eddies (in turbulent flow) or the striations (in laminar flow), see s. (4.8) and (4.16). However, with sufficiently intense turbulence, or in vigorously stirred viscous media, the micro-mixing times may be completely determined by rapid deformation of small liquid elements. The micro-mixing time may then be equal to the "engulfment time" in turbulent flow, or the "deformation time" in laminar flow see equations (4.10 and (4.19). Micro-mixing times in turbulent flow are generally on the order of 10 to 1 s, and in laminar flow they can be anywhere between 10 and 10 s. 

---