A streamline represents the path of a massless particle moving within a flow, traced tangentially to the velocity vector. Laminar flows indicate smooth, regular airflow patterns, while turbulent flows involve disruptions creating swirling eddies. Streak lines depict the positions of fluid particles passing through a specific point at a given moment.

1. A streamline is a path traced out by a massless
particle as it moves with the flow.
OR
A streamline is one that is drawn tangential to the
velocity vector at every point in the flow at a given
instant and forms a powerful tool in understanding
flows.

2. Stream lines

3. Explanation
A moving body causes the air to flow around it in definite
patterns, the components of which are called
streamlines.
 Smooth, regular airflow patterns around an object are
called laminar flow they denote a minimum of
disturbance of the air by the object’s motion through it.
Turbulent flow occurs when air is disturbed and
separates from the surface of the moving body, with the
consequent formation of a zone of swirling eddies in the
body’s wake.

4. Streak line
The locus of all the points that have gone through a given point
in a flow is called streak line.
 It concentrates on fluid particles that have gone through a
fixed station or point. At some instant of time the position of
all these particles are marked and a line is drawn through
them. Such a line is called a streak line

5. Streak line