They also explore behaviour in much of the available parameter space.
The parameter space is rather large, and only a small subspace is explored in the numerics. This is fine, but it leaves a lot of interesting questions un-addressed. For example, is the transition from broad streams (Figure 4a) to loops (Figure 4d) continuous or are there bifurcations/phase transitions? Can you coarse grain this model to make it analytically tractable? The basic phenomena suggest something like an active shear-thinning uid? This would make it easier to understand the bifurcations in the dynamics and may require fewer parameters. Just something to think about.