Definition of streamline (laminar) flow The flow in which each fluid particle follows a definite path and the paths of adjacent particles do not intersect is called:

Introduction / Context:
Fluid motions are categorized to analyze stability, mixing, and energy losses. A key distinction is between orderly, layered motion and random, fluctuating motion. The former is described by streamlines that never cross.

Given Data / Assumptions:

• Inviscid or viscous fluids may both exhibit streamline (laminar) behavior at sufficiently low Reynolds numbers.
• Paths are conceptual curves tangent to the velocity vector at every point.

Concept / Approach:
Streamline (laminar) flow is characterized by smooth, parallel layers; each particle follows a fixed path, and neighboring paths do not intersect. This differs from “steady flow” (no time variation at a point) and “uniform flow” (no spatial variation along a reach). Turbulent flow has random fluctuations and eddies.

Step-by-Step Solution:

Verification / Alternative check:
In dye-streak experiments at low Re, a thin colored filament stays coherent—indicating streamlines that do not intersect.

Why Other Options Are Wrong:

• Uniform flow: property constancy along space, not about particle paths crossing.
• Steady flow: time invariance at a fixed point; streamlines can still be complex.
• Turbulent flow: inherently involves fluctuating, intermingling paths.

Common Pitfalls:
Equating “steady” with “laminar”—they are independent attributes; a steady flow can be turbulent.

Final Answer:
stream line flow