RHEOLOGY PART 5: LESSONS FROM A DROP OF HONEY!

Sometimes we can learn more about the problems of rheology and mixing of fermentation broth by observing simple examples such as a drop of honey. A drop of honey as a rheological model is not truly reflective of the behavior of the fermentation broth but its behavior will allow you insights of mixing non Newtonian fluid.
If we try to stir the drop of honey on a surface using a tooth pick, we will see that it is very difficult to mix the drop of honey homogenously. There is movements by the tooth pick, but in most cases the honey will try to resist the movement and retract elastically back to its mass. Even if mixing occurs temporarily, it only occurs within the close proximity of the stirrer. Increasing the speed of mixing at most times does not increase the mixing of the honey.
Are we trying to say that in fermentors with very viscous broth mixing comes to nothing? Or better still have we come with properly designed stirrers that can really effectively stir the fermentation broth?
The biochemical engineers need to understand more about the properties of the non Newtonian broth and designed new stirrer configurations or even new modes of mixings to overcome this problem. Maybe it is high time or over time that they should start to look at the micromixing aspects rather than be over whelmed by macro mixing properties




Type rest of the post here.