Under What Conditions Will Pathlines Streamlines And Streaklines Be Considered The Same?

Under What Conditions Will Pathlines Streamlines And Streaklines Be Considered The Same? Streamlines, streaklines and pathlines are field lines in a fluid flow. They differ only when the flow changes with time, that is, when the flow is not steady. Under what condition do streamlines of a flow coincide with the streak lines? It is