  This paper investigates the bistability of curved compression ramp (CCR)
flows. It reports that both separated and attached states can be stably
established even for the same boundary conditions, revealing that the ultimate
stable states of CCR flows also depend on the initial conditions and
evolutionary history. Firstly, we design a thought experiment involving two
establishment routes of CCR flows, constructing two distinct-different stable
states, respectively. Subsequently, three-dimensional direct numerical
simulations are meticulously performed to instantiate the thought experiment,
verifying the existence of the bistable states. Finally, we compare the
pressure, wall friction, and heat flux distributions under two stable states.
As a canonical type of Shock wave-Boundary 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.
