In the production and processing of materials it is very common to bring components together into a mixture of some sort. The components may be miscible fluids and can be dispersed in each other down to the molecular level, with the issues being how fast the mixing can be accomplished, how much power is required, and how uniform the proportions are across the bulk of the mixture. The components may be immiscible phases: the issues are still speed, power and uniformity of mixing but also the scale down to which dispersion can be and has to be achieved.
Two general situations requiring mixing are：
- Bringing components together for inter-phase mass transfer or for chemical reaction.
- Blending components together to make a product.
CD agitator design and produce mixer for following four different combinations of components that have to be mixed:
- miscible liquids
- immiscible liquids
- gas and liquid
- solid particles in liquid