Whereas liquid oxygen is quite a dense fluid, hydrogen fuel has an exceptionally low density and takes up much more volume.

At the bottom dense fluid flows towards the head.

It can be used to make dense fluids for drilling oil wells.

Less dense fluids float on more dense fluids if they do not mix.

This concept can be extended, with some care, to less dense solids floating on more dense fluids.

Measurements are carried out in a rotating horizontal tube which contains a dense fluid.

Sodium bromide is used to prepare dense fluids used in oil wells.

As the waters surged, they carried a dense, salty fluid which formed a network of sea-floor channels that are almost constantly active, even today.

If one uses a very dense fluid inside the membrane, the growth is downward.

The lower dense fluids (air is considered a fluid in engineering terms) will always "rise to the top" of a mixed fluid system.