Fractal Viscous Fingering pattern during the fast drainage of a porous medium
![](https://www.mn.uio.no/fysikk/english/people/aca/mnmoura/image-gallery/invadingmatrix_viscousfingering_circularcell_image_450.png)
This interesting fractal pattern is observed when a less viscous fluid (air here) is injected into a Hele-Shaw cell filled with a porous medium saturated with a more viscous fluid (a glycerol-water mixture here).