Figure above : Pattern formation in the Hele-Shaw cell (two flat plates -- one transparent -- between which is enclosed a layer of viscous liquid), in which a liquid (here the clear liquid) is injected into a more dense liquid (colored) under pressure. Depending on the injection pressure and other factors, different bubble shapes can be observed that are reminiscent of those seen in electrodeposition ( = the deposition of metal clusters by applying a voltage to an electrode dipped in a solution of metal ions).
Shown here are (1) DLA-like (top-left) -- "DLA" means diffusion-limited aggregation, (2) dense-branching (top-right) and (3) dendritic (bottom) growth. For the latter, some directional preference must be introduced, for example by scoring the face of one of the two plates with a lattice of grooves. The square lattice in this example generates a "snowflake" with fourfold symmetry.
I've been looking into hele-shaw cell experiments of form generation.
I want to experiment with this.