path line

path line — noun

1. the curved track that one small bit of a moving liquid or gas follows over a per

1.nounC2
Definition

the curved track that one small bit of a moving liquid or gas follows over a period of time, used by scientists to picture how the flow moves.

Example

Faisal dropped blue dye into the river to reveal the path line of the current.

the path line of [moving fluid]

The wind-tunnel camera traced the path line of a single smoke particle past the wing.

traced the path line of [a particle]

Common collocations
  • trace a path line
  • the path line of a particle
  • path line in the simulation
Synonyms
  • pathline

    the same term written as one word; common in engineering papers

  • particle path

    plainer wording for the route a single particle takes

Grammar Patterns

the path line of [something moving]

Usage Note

Distinguish from a streamline: a path line records where one particle has actually travelled over time, while a streamline shows the flow direction everywhere at a single instant.

Common Mistakes

The path line shows the flow at this moment.
The streamline shows the flow at this moment.
a path line records movement over time, not a single instant.

Etymology

English

A compound of the everyday English words 'path', meaning the route something travels, and 'line', meaning a thin continuous mark. The two were joined in physics and engineering to name the visible track left by a moving particle of fluid.