Because of heat from the nuclear material, the water circulates constantly.

Oil circulates through them constantly, so they can reach peak power within six seconds of being switched on.

The hydrologic cycle keeps water constantly circulating on the Earth.

Janey and Andrea simply circulated constantly, as did the cats.

The water, she was glad to note, constantly circulated, the cloudy and dirty replaced with clear.

The serum was constantly circulated by a series of tiny, ingenious pumps inside the case.

Blood is a constantly circulating fluid providing the body with nutrition, oxygen, and waste removal.

Rumours were constantly circulating that George would be the tsarevich's replacement.

People circulated constantly in the increasingly crowded antechamber, waiting impatiently for their chance to see and be seen.

It is now constantly circulated and purified by irradiation.