Figure 2—-Summary of viscous fingering experiments (based on Lee et al. 2020) (a): Hele-Shaw images (b): Micrographs of produced samples *XG: Xanthan Gum, AS: Anionic surfactant.
In our previous visual analysis work using steam and polysorbate at thermal conditions at 200°C (Bruns and Babadagli 2020) and cationic surfactant at non-thermal conditions (Lee et al. 2020), droplet generation could be seen in both cases (following the predicted tip-splitting fingers) bearing a striking resemblance in their appearance to the droplet development encountered in partially-miscible fluid flow (Figure 3 ).