On the disputes about open separation

Refutations are offered to challenges to the validity of the open separation concept in three-dimensional flows. Tobak and Peake's (1979, 80, 81) assertions using Lighthill's concept for the streamline which passes through a saddle point and separates is confronted on topological grounds, and on the basis of terminology. It is shown that Tobak and Peake reiterated the present author's definitions in new terms, while assigning the author's work to a special case of the phenomena while it is in actuality a general description. Cebeci et al. (1981) are cited as having a different view of separation. Differences in predictions are noted to occur only at high angles of attack. Furthermore, Cebeci et al. are suggested to have neglected the inclusion of a close proximity of the zero-c line and the separation line, although the two are distinct. Phenomena occurring at high angle of attack are discussed.