Flow Description — Pathlines That Never Cross A flow in which each liquid particle follows a definite path and the paths of individual particles do not intersect is called:

Introduction:
Describing flow patterns helps choose appropriate models. One useful idealization is streamline (laminar) flow, where orderly layers slide over one another and particle paths are well defined.

Given Data / Assumptions:

• Incompressible liquid with moderate Reynolds number.
• No mixing across streamlines; negligible instabilities.
• Observation over a period where the pattern remains representative.

Concept / Approach:
In streamline (laminar) flow, neighboring particles follow smooth, non-intersecting paths. Streamlines show the instantaneous direction of the velocity field and cannot cross because velocity at a point has a unique direction.

Step-by-Step Solution:
Define streamline: line everywhere tangent to the instantaneous velocity vector.Argue non-intersection: two directions at one point would be required to cross, which is impossible for a single-valued velocity field.Therefore the correct term is streamline flow.

Verification / Alternative check:
Low-Re flows in narrow tubes or viscous oils exhibit dye streaks that remain layered and do not mix rapidly, matching the streamline behavior.

Why Other Options Are Wrong:
Steady refers to time invariance; uniform refers to spatial constancy; turbulent features random fluctuations and enhanced mixing, where pathlines may get highly convoluted.

Common Pitfalls:
Equating steady with laminar; assuming streamlines represent time-averaged motion in turbulence (they do not).

Final Answer:
streamline flow