Midterm 2

Question 1

Lagrangian Viewpoint

Answer 1

Considers the motion of an individual fluid particle. Same as sitting on a fluid particle and noting the changes in its location, velocity, density, etc, over time.
Used in solid mechanics
Velocity is only a function of time

Question 2

Eulerian Viewpoint

Answer 2

Considers the motion of a particle moving by a particular location or point in a fluid system. Similar to sitting at a particular location and observing the fluid particles move by. This is the method used in fluid dynamics. Velocity is a function of time and position.

Question 3

Who first identified Laminar and Turbulent flow

Answer 3

Osborne Reynolds

Question 4

Laminar Flow

Answer 4

characterized by an absence of turbulence and associated eddies and mixing. Flow appears smooth. Eg. Honey, thick syrup, viscous. Particle paths are definite and observable. Velocity distribution is parabolic. Reynolds number is below 2000.

Question 5

Turbulent Flow

Answer 5

characterized by mixing, eddies, and small-scale velocity fluctuations. Particle movement appears irregular and erratic. Eg Smoke from a chimney, gust of wind. Mean velocity distribution is relatively uniform due to the mixing of high and low velocity particles within the flow field. Reynolds number above 2000.

Question 6

What are the four ways fluid flow can be defined?

Answer 6

Steady or unsteady
Turbulent or Laminar
Dimensionality
Uniform and non-Uniform

Question 7

One dimensional flow

Answer 7

flow properties vary in ONLY one direction

Question 8

Two-Dimensional Flow

Answer 8

flow properties vary in two dimensions

Question 9

Three-Dimensional Flow

Answer 9

flow properties vary in all three cartesian coordinate directions

Question 10

Axi-Symetrical Flow

Answer 10

Flow properties vary in both a longitude and radial direction. Type of 3d flow. Eg. Bullet travelling

Question 11

Steady

Answer 11

constant rate of flow through a pipe

Question 12

Unsteady

Answer 12

opening or closing or a valve on a pipeline

Question 13

Three Flow Properties

Answer 13

Pressure, density, velocity

Question 14

Time Variation

Answer 14

flow properties do/do not change at a particular location with time

Question 15

Location Variation

Answer 15

flow properties do/do not change with position along a flow path

Question 16

Uniform

Answer 16

flow through a pipeline of a CONSTANT DIAMETER

Question 17

Non-Uniform

Answer 17

flow through a pipe transition from a large diameter to a small diameter.

Question 18

Streamline

Answer 18

a line drawn through a flow field in such a manner that the velocity vector of the fluid at each and every point on the streamline is tangent.

Question 19

Three types of Flow Pattern, When are they all the same

Answer 19

Streamline, Streaklines and Pathlines .

They are all the same when it is a steady flow

Question 20

Streamtube:

Answer 20

a flow passage bounded by a series of streamlines drawn through a closed curve.

Question 21

Pathline

Answer 21

a line drawn through the flow field such a way that it defines the route taken by a particle in moving through the flow field.

Question 22

Strealine

Answer 22

the trace of the flow pattern in a flow field made by inserting dye or smoke into the flow field