  We study the buckling of a clamped beam immersed in a creeping flow within a
rectangular channel. Via a combination of precision experiments, simulations,
and theoretical modeling, we show how the instability depends on a pressure
feedback mechanism and rationalize it in terms of dimensionless parameters. As
the beam can bend until touching the wall above a critical flow rate, we
finally demonstrate how the system can be used as a tunable passive flow
selector, effectively redirecting the flow within a designed hydraulic circuit.
