1: Kinematics of Fluids

Question 1

pick fixed point x and ask - what is the velocity at time t of the fluid particle at x

Answer 1

eulerian description of velocity

Question 2

pick particle at fixed point a and track it - ask what is the velocity at time t of the fluid particle that started at a

Answer 2

lagrangian description of velocity

Question 3

the path x(t) of a fluid particle over time

Answer 3

particle path

Question 4

a curve of all fluid elements that passed through a given point in the past

Answer 4

streakline

Question 5

streaklines are ___ particle paths

Answer 5

not necessarily

Question 6

___ are parallel to u

Answer 6

streamlines

Question 7

fluid can’t leave the area bounded by ___ because u is parallel to ___

Answer 7

streamlines

Question 8

u.n=0

Answer 8

no normal flow condition for solid boundary in an inviscid fluid

Question 9

material derivative u.grad part

Answer 9

fluid particle is being carried by flow along grad(curve)

Question 10

density of fluid element doesn’t change as it moves

Answer 10

incompressible

Question 11

how much u in the direction of the curve as we go around the curve

Answer 11

circulation

Question 12

vortex lines/tubes are analogous to ___lines/tubes

Answer 12

stream

Question 13

a flow with no vorticity everywhere

Answer 13

irrotational