The transonic turbulent two-dimensional airflow over a symmetric flat-sided double wedge is studied
numerically. Solutions of the Reynolds-averaged Navier-Stokes equations are obtained with ANSYS-18.2 CFX
finite-volume solver of second order accuracy on a fine mesh. The solutions demonstrate an extreme sensitivity
of the flow field and lift coefficient to variation of the angle of attack α or free-stream Mach number M∞. Nonunique flow regimes and hysteresis in certain bands of α and M∞ are identified. Interaction of shock waves
and local supersonic regions is discussed. The study confirms a concept of shock wave instability due to a
coalescence/rupture of supersonic regions. In addition to the instability of shock wave locations, the numerical
simulation shows a buffet onset, i.e., self-exciting oscillations due to instability of a boundary layer separation
at the rear of wedge. Curious flow regimes with positive lift at negative angles α and, vice versa, with negative
lift at positive angles α, are pointed out. A piecewise continuous dependence of the lift coefficient on two freestream parameters, α and M∞, is discussed.