Calculation of the Stability of Heated Boundary Layers Using the Compound Matrix Method

Abstract : A fourth-order Orr-Sommerfeld eigenvalue solver for heated boundary layers has been implemented on the VAX-11/785 computer. The solver is based on the compound matrix method and the effects of heating are limited to mean viscosity variation across the boundary layer. Some test computations have been carried out on flat plates with uniform wall temperature. For small overheat, the results agree with those previously published using other methods, but for large overheat, there are some minor differences. The calculation procedure requires a large number of integration steps across the boundary layer to obtain accurate eigenvalues, but is relatively insensitive to other physical and numerical parameters. A few computations have been carried out using a full sixth order model, which takes into account fluctuations in all the fluid properties. It is concluded that the fourth order method can be incorporated into an axisymmetric body calculation procedure.