To check the sensitivity of the F-advection algorithm used in SOLA-VOF this problem was repeated with F advective flux determined entirely by the downstream or acceptor cell F values. This pure acceptor-cell method, which differs from the mixture of donor—acceptor flux used in the SOLA-VOF code, has been used in some previous work (see, e.g., Ref. [14]). The consequences of using pure acceptorcell flux are obvious from a comparison of Fig. 11 with Fig. 10. The acceptor-cell method develops large irregularities in the free surface, particularly where it is flowing parallel to itself. This does not occur in the SOLA-VOF method because it uses donor cell flux in such regions.