Inviscid and Incompressible Flow

Question 1

What are the three main conservation laws to consider when dealing with fluid flow?

Answer 1

• Mass
• Momentum
• Energy

Question 2

Why must the inlet flow equal the outlet flow within a pipe?

Answer 2

Because if they aren’t, there will be an accumulation of mass, which will lead to changing densities, which means there is compression which isn’t allowed

Question 3

What is the bulk velocity of a fluid?

Answer 3

This is an average value of velocity, despite the fact that velocity is varying
If we take the mass flow rate and divide it by the density and the area it’s passing through, then we will find the average velocity

Question 4

When would we benefit using the bulk velocity?

Answer 4

If we have uneven ducts or non-uniform flow

Question 5

What is the Bernoulli Equation, and what do each group of terms represent in a fluid dynamics viewpoint?

Answer 5

p + 1/2 * rho * U^2 + rho * g * z = Constant

These represent the Static, Dynamic and Hydrostatic Pressure respectively
The sum of all three represents the total pressure which can also be called the stagnation pressure

Question 6

What does it mean if we have a fast flow?

Answer 6

There will be a low pressure, meaning that there will be a curving path towards the side of the fast flow since there is a pressure difference

Question 7

Using the concept of momentum, what is Newton’s Second Law

Answer 7

F = ma
Force is the rate of change of momentum
a = dv/dt
ma = mdv/dt
mv = Momentum

Question 8

What is the relationship between the stream function and a streamline?

Answer 8

Along a streamline, the stream function will have a constant value

Question 9

What is the stream function physically related to?

Answer 9

The stream function is related to the flow rate as it’s the amount of flow passing between streamlines

Question 10

What is the vorticity?

Answer 10

It’s the circulation per unit area