A treatment of asymptotic calculation of upper branch nonstationary instsab
ility modes is undertaken in the boundary layer flow due to a. rotating dis
k. A numerical spectral solution of the eigenvalue problem shows good agree
ment with the results of a rational asymptotic approach, based on the exten
sion of the multideck theory of [1]. (C) 2001 Elsevier Science Ltd. All rig
hts: reserved.