文档介绍：Problem Set 2B Name: ____________________
Assigned: Thursday, September 13
Due: Tuesday, September 18
1. Complete the following statements:
a) If you took a long time-exposure photograph of a luminous particle moving with
the flow in a river, the image would be a ( pathline , streakline , streamline ).
b) A ___________________ is a curve in a flow field which has the property that
the velocity vector of each particle on the curve is tangent to the curve.
c) There are a ( finite , variable , infinite ) number of streamlines in a flow field.
v v
d) If dR is the infinitesimal displacement vector along a streamline and V is the
v v
velocity of a particle on the streamline, then dR ×V = ________ .
e) If you continuously inject dye at a fixed point into a flowing fluid in such a way
that the dye particles essentially match the speed of the fluid as they enter the
flow, the pattern of dye you see in a snapshot of the flow is a ( pathline ,
streakline , streamline ).
f) A streamline is an ( Eulerian , Lagrangian ) concept.
g) A pathline is an ( Eulerian , Lagrangian ) concept.
2. If you saw a plot of a flow in which two initially separate streamlines eventually
intersected with each other at a point, what would that necessarily tell you about the fluid
velocity at that point? Why?