- #1

- 99

- 1

*Non dimensional momentum flux is defined as the drag coefficient*In case of flow through tubes it states

*The non dimensional momentum flux is defined as the friction factor*What do these statements mean? What do they practically define?

You are using an out of date browser. It may not display this or other websites correctly.

You should upgrade or use an alternative browser.

You should upgrade or use an alternative browser.

- Thread starter Rahulx084
- Start date

- #1

- 99

- 1

In case of flow through tubes it states

What do these statements mean? What do they practically define?

- #2

Chestermiller

Mentor

- 21,056

- 4,641

For flow past an object, the relationship between the drag force F and the dynamic pressure ##\frac{1}{2}\rho v^2## is expressed as $$\frac{F}{A}=C_D\left(\frac{1}{2}\rho v^2\right)$$where A is the projected area of the object. Since dynamic pressure has units of momentum flux (and, mechanistically, can be regarded as a momentum flux), and since F/A also has units of momentum flux, ##C_D## is thereby sometimes regarded as a dimensionless momentum flux. I personally don't like this interpretation, and it does nothing for me.

In the case of fluid flow in a tube, the relationship between the shear stress at the wall ##\tau## and the dynamic pressure ##\frac{1}{2}\rho v^2## is expressed as $$\tau=f\left(\frac{1}{2}\rho v^2\right)$$where f is the Fanning friction factor. Since dynamic pressure has units of momentum flux (and, mechanistically, can be regarded as a momentum flux), and since the wall shear stress ##\tau## also is interpreted as momentum flux, f is thereby sometimes regarded as a dimensionless momentum flux. I personally don't like this interpretation, and it too does nothing for me.

- #3

- 99

- 1

- #4

Chestermiller

Mentor

- 21,056

- 4,641

Don't worry about that now. You'll get the idea once they teach you how to approach problems. Your time is too valuable to worry about this for now.

- #5

- 99

- 1

- #6

Chestermiller

Mentor

- 21,056

- 4,641

Sorry to hear that. You can count on us at Physics Forums to help you in any way we can.My teacher,she doesn't give a **** about what she teaches . Our university have appointed her just because of her approaches to dean . Thats why I was asking you sir .

- #7

- 99

- 1

- #8

Chestermiller

Mentor

- 21,056

- 4,641

When you begin a new topic, please start a new thread.

- #9

- 99

- 1

Actually the question is from the same topic the thread I started few days ago , so I thought maybe its okay to ask hereWhen you begin a new topic, please start a new thread.

- #10

Chestermiller

Mentor

- 21,056

- 4,641

In my judgment as a Physics Forums moderator, it's not, so please start a new thread.Actually the question is from the same topic the thread I started few days ago , so I thought maybe its okay to ask here

Share:

- Replies
- 2

- Views
- 2K