The viscous boundary layer concept for the shocked solar wind at the flank regions of the Venusian ionopause is discussed in connection with the most recent experimental results of the Venera 9 and 10 data analysis. The observed dynamics of the plasma in the near wake give further support to the view that the shocked solar wind interacts viscously with the ionospheric material in the vicinity of the planetary terminator. Considerations of mass flux conservation within the ionosheath flow suggest that solar wind protons should be a major component of the plasma density in the wake.