Which of the following characteristics regarding fluid kinematics is/are correct?

1. Streamline represents an imaginary curve in the flow field so that the tangent to the curve at any point represents the direction of instantaneous velocity at that point.

2. Path lines, streamlines and streak lines are identical in steady flow. 

Concept:

Streamline is a line everywhere tangent to the velocity vector at a given instant

Path line is the actual path traversed by a given fluid particle.

The streak line is the locus of particles that have earlier passed through a prescribed point.

For steady flow, streamlines, pathlines, and streak lines are identical because:

• For a steady flow, the velocity vector at any point is invariant with time.
• The path line of the particles with different identities passing through a point will not differ.
• The path line could coincide with one another in a single curve which will indicate the streak line too.