Which fluidics principle allows gas to exit through only one output port?

• A. Beam Deflection
• B. Flow Control
• C. Split-Flow
• D. Wall Attachment

Answer: (D)

Gas exiting through a single port is achieved by a phenomenon where the jet clings to and follows a nearby wall, guiding the flow along that surface toward one outlet. This is the wall attachment effect (often tied to the Coandă effect), where viscosity and the surrounding flow create a pressure pattern that makes the jet stay attached to the wall instead of branching off to multiple paths. By steering the jet along the wall, the flow naturally ends up at one designated exit and avoids splitting.

The other ideas don’t produce this single-path outcome: beam deflection relies on pushing or steering the jet with a barrier, which can still route flow to multiple paths depending on the setup; flow control is a broad term about adjusting rate rather than routing; split-flow is specifically about dividing the stream among several outlets. Wall attachment is the mechanism that redirects and confines the flow to a single exit.