The research team placed the scale model of the submarine in the water tunnel to measure the flow patterns around the hull.

The engineers spent weeks in the wind tunnel testing scale models of the new aircraft to refine its aerodynamics.

During the winter, maintenance crews inspected the steam tunnel to locate leaks in the campus heating system.

The explorers stepped cautiously into the time tunnel, unsure which era they would emerge in.

The engineer used a tunnel diode to stabilize the oscillator's frequency.

We took the Eurostar through the Channel Tunnel to Paris, enjoying the comfort and speed of the undersea rail link.

As a tunnel rat, he crawled into the narrow, dark passages to locate enemy fighters and render their explosives safe.

During the reconnaissance mission, the tunnel rats volunteered to enter the cramped passageways to search for hidden weapons.

Laughing nervously, they drifted together in a creaky boat through the tunnel of love, unsure whether the ride would be tender or designed to give them a good fright.

The tunnel-visioned researcher continued to pursue a single hypothesis, ignoring valuable evidence that pointed elsewhere.