## Froude Number Equations

## Froude Number Equations

(OP)

Dear Colleagues,

I found in a literature the different form of the Froude No. equation: Fr= V^2/g*D, instead of the well-known form: Fr= V/SQRT(g*D).

At the same velocity the equations gave the different Froude numbers.

Which of the equations is more correct?

Thank you,

Mike

I found in a literature the different form of the Froude No. equation: Fr= V^2/g*D, instead of the well-known form: Fr= V/SQRT(g*D).

At the same velocity the equations gave the different Froude numbers.

Which of the equations is more correct?

Thank you,

Mike

## RE: Froude Number Equations

Ha - trick question. They both are. However: https://en.wikipedia.org/wiki/Froude_number#Defini... suggests the second one is the correct one.

## RE: Froude Number Equations

Good Luck,

Latexman

## RE: Froude Number Equations

Remember - More details = better answers

Also: If you get a response it's polite to respond to it.

## RE: Froude Number Equations

That isn't to say that one of them doesn't reduce to the first one, but I don't know of it.

= = = = = = = = = = = = = = = = = = = =

P.E. Metallurgy, consulting work welcomed

## RE: Froude Number Equations

I found the 1st equation in the "Beggs-Brill Two--phase flow in pipes" book. Please see the attached. In the equation Vm is 2-ph mixture velocity.

For which applications the 1st and 2nd forms are applicable?

Thanks, Mike

## RE: Froude Number Equations

## RE: Froude Number Equations

## RE: Froude Number Equations

Squaring is normally done to eliminate negative values; if somehow a negative velocity crept in, that would be taken care of.

I see the same construction in https://www.sciencedirect.com/topics/engineering/f... as used in a number of articles.

## RE: Froude Number Equations

^{1/2}time and time again. Again, that's me speculating.If you are using the correlations, charts, graphs, etc. in their book, use their definition.

If you are not using the resources in their book, use v/(gd)

^{1/2}.Or, it's an error in their book. Try to search for errata for the book, or contact the authors, if they are still alive.

My $0.02.

Good Luck,

Latexman

## RE: Froude Number Equations