Passive Mixing

Passive Mixing and Concentration Tracking Using Scalars

Passive mixing schematic

Schematic showing just how small a desired mixing length can be. The pure liquid will enter the top and the mixture will enter the bottom; flow is from left to right. Ideally, the two streams would be fully mixed by the end of the 2000micron chamber.

The mixing of multiple streams of fluids in micro channels/chambers is of great importance in bio-analytical systems. Typically these processes need to occur within short mixing lengths and time scales. Passive micro-mixers make use of the geometry of the micro-channel to induce mixing. Shown here is a design variation where the liquid plus reagent side uses a passive scalar to show the mixing concentration. In this case, the two fluids had nearly identical viscosities but FLOW-3D is capable of modeling different viscosities and densities mixing as well.

Demonstration of a passive micro channel mixing process. The colors represent the concentration of the two different fluids (blue =  Pure liquid, red = Liquid + Reagent).