The prediction of separation bubbles on NACA 65 - 213 and NACA 0012 using a modified Chen - Thyson transition model is presented . The contents include : 1 ) Background ; 2 ) Analysis of NACA 65 - 213 separation bubble using cebeci 's viscous - inviscid interaction method ; 3 ) Analysis of NACA 0012 separation bubble using navier - stokes method ; and 4 ) Comparison with experiment .