# What is fourier number?

1. Apr 27, 2010

### New2thermodyn

What is fourier number??

What exactly is fourier number??? I kno its Thermal diffusivity*time/square of radius. But what exactly is the meaning of Fourier number???

For eg: Why do we calculate Fourier number for finding out the lumped heat in solids???

2. Apr 27, 2010

### mathman

3. Apr 27, 2010

### New2thermodyn

Re: What is fourier number??

Thanks Mathman, and yes,Of course iv checked wikipedia b4 posting that question!!! In wiki it is just the explanation of the terms involved, ie"the ratio of the heat conduction rate to the rate of thermal energy storage", is not that pretty obvious just looking at the equation???? but what i want to know is the significance of the equation

4. Apr 28, 2010

### mathman

Re: What is fourier number??

5. Apr 28, 2010

### Mapes

Re: What is fourier number??

When the Fourier number is much larger than one, the conduction process is predicted to have reached steady state. Does this answer your question?

6. Dec 16, 2010

### blacktail

Re: What is fourier number??

Fo = (Heat conduction rate)/(thermal energy storage rate)
Fo = [k A [STRIKE]dT[/STRIKE]/dx]/[(dm/dt)*Cp*[STRIKE]dT[/STRIKE]] -------------> dx = L
Fo = [kA/L]/[ρ*Cp*Q] -----------------------> A/Q = t/L
Fo = [kt]/[ρ*Cp*(L2)]---------------------->k/ρ*Cp = α
Fo = αt/L2