Nonuniqueness of the Transonic Flow past an Airfoil

The inviscid transonic flow past a symmetric airfoil having a curvature minimum in the middle is numerically investigated. It is shown that at zero angle of attack alpha both symmetric and asymmetric steady-state flow patterns can exist on a certain freestream Mach number range M-min < M-infinity < M-max. On this range, the asymmetric flows are stable against small perturbations, whereas the symmetric flows are stable only if M-infinity does not coincide with a singular Mach number at which small variations in M-infinity or alpha can result in flow restructuring.