Enter the thermal diffusivity (m^2/s) and the mass diffusivity (m^2/s) into the Calculator. The calculator will evaluate the Lewis Number.

## Lewis Number Formula

Le = a / Dc

Variables:

- Le is the Lewis Number ()
- a is the thermal diffusivity (m^2/s)
- Dc is the mass diffusivity (m^2/s)

To calculate Lewis Number, divide the thermal diffusivity by the mass diffusivity.

## How to Calculate Lewis Number?

The following steps outline how to calculate the Lewis Number.

- First, determine the thermal diffusivity (m^2/s).
- Next, determine the mass diffusivity (m^2/s).
- Next, gather the formula from above = Le = a / Dc.
- Finally, calculate the Lewis Number.
- After inserting the variables and calculating the result, check your answer with the calculator above.

**Example Problem : **

Use the following variables as an example problem to test your knowledge.

thermal diffusivity (m^2/s) = 15

mass diffusivity (m^2/s) = 123