fluid mech exam 2

Question 1

Reynolds Number

Answer 1

used to determine if the flow is laminar or turbulent, depending on velocity, density, viscosity, and length/diameter

Question 2

Buckingham Pi theorem

Answer 2

number of variable-number of units= number of dimensionless terms

Question 3

How can a scale model be used

Answer 3

can set two dimensionless terms equal to each other and find desired variable

Question 4

EGL

Answer 4

energy grade line

Question 5

HGL

Answer 5

hydraulic grade line

Question 6

HGL-EGL

Answer 6

Kinetic energy (V^2/2g)

Question 7

How can an HGL/EGL diagram be useful

Answer 7

the HGL shows us the elevation water can flow up to in a pipeline. This is important for deciding if a pipeline system can provide sufficient pressure to all customers in a pipe system.

Question 8

when is an iterative solution necessary

Answer 8

when an unknown variable is needed multiple times in an equation

Question 9

major loss

Answer 9

loss as dependent on the length of a pipe

Question 10

minor loss

Answer 10

energy loss as dependent on the other features such as bends, constrictions, expansions, pipe fittings, valves etc.

Question 11

water hammer

Answer 11

a pressure surge the propagates through a pipe system when a valve is shut too quickly, can be mitigated by slowly closing pipe (Tslow= 2L/c where c=sqrtEb/rho)