Stability of threedimensional supersonic boundary layers Academic Article uri icon


  • A rotating cone that is located in a supersonic free stream at zero angle of attack is used as a model to investigate the stability of three-dimensional supersonic boundary layers. The boundary-layer profiles on the surface are calculated using the Cebeci-Keller box scheme. The stability equations are solved to determine the eigenvalues using a two-point fourth-order finite-difference scheme [Malik et al., Z. Angew. Math. Phys. 33, 189 (1982)]. The results show that the amplification rate of the first mode is increased by a factor of 2 to 4 due to the cross-flow, compared with a two-dimensional flow with the same streamwise profile. This increase decreases with increasing Mach number. The instability with cross-flow covers a wide range of unstable frequencies (including zero) and wave numbers. The results also show that the second mode in a three-dimensional boundary layer is oblique whereas the second mode in a two-dimensional boundary layer is two dimensional. The maximum amplification rate of the second mode decreases more slowly with increasing wave angle in a three-dimensional boundary layer than in a two-dimensional boundary layer. It is concluded that the cross-flow instability becomes important for cross-flow Reynolds number on the order of 50 for low Mach numbers and 100 for high Mach numbers, this Reynolds number range corresponds to a maximum cross-flow velocity of about 4%. 1991 American Institute of Physics.

published proceedings

  • Physics of Fluids A: Fluid Dynamics

author list (cited authors)

  • Balakumar, P., & Reed, H. L.

citation count

  • 46

complete list of authors

  • Balakumar, Ponnampalam||Reed, Helen L

publication date

  • April 1991