The numerical results are less good for this part. Effectively, we think the effect of surface tension sets up problems concerning the interface. If we look at Fig 4.7 we can see that the interface doesn't have the real shape of Kelvin Helmholtz instability. We don't know exactely what's happend but maybe it is due to the value of surface tension which is not the right value for water-liquid and fuel-oil-liquid.
The results obtained about pressure, streamlines and cat's eye are a little modified because of this problem but the idea is the same than at the section 4.1.1 where surface tension was absent.