  This paper reports the bistability of curved compression ramp (CCR) flows. It
reveals that both separation and attachment states can be stably established
even for the same boundary conditions. Firstly, to investigate the effects of
initial condition and evolutionary history, a thought experiment involving two
processes with the same three steps but in different orders is designed,
possibly constructing the two distinct-different stable CCR flows.
Subsequently, three-dimensional direct numerical simulations are then performed
to replicate the thought experiment, verifying the existence of the bistable
states in CCR flows. In the end, the method of virtual separation disturbance
is proposed to detect whether potential bistable states exist, theoretically
demonstrating the bistability of CCR flows. As a canonical type of Shock
waveBoundary layer interactions, local CCR flows often appear on aircraft,
hence the bistability will certainly bring noteworthy changes to the global
aerothermodynamic characteristics, which supersonic/hypersonic flight has to
deal with.
