First Knudsen Number
The Knudsen number is a dimensionless number defined as the ratio of the molecular mean free path length to a representative physical length scale.
The first Knudsen number equals the mean free path divided by the characteristic length.
Formula
![Copy to Clipboard QuantityVariable[Subscript["Kn", "1"], "KnudsenNumber1"] == QuantityVariable[Subscript["l", "mfp"], "MeanFreePath"]/QuantityVariable["l", "Length"]](https://www.wolframcloud.com/objects/resourcesystem/marketplacestorage/resources/e6a/e6ae7d32-f78c-4905-b3f2-ff626af1c776/Webpage/FormulaImage.png)
| symbol | description | physical quantity | 
|---|---|---|
| Kn1 | first Knudsen number | "KnudsenNumber1" | 
| l | characteristic length | "Length" | 
| lmfp | mean free path | "MeanFreePath" | 
Forms
Examples
Get the resource:
| In[1]:= | ![ResourceObject["First Knudsen Number"]](images/e6a/e6ae7d32-f78c-4905-b3f2-ff626af1c776-io-1-i.en.gif) | 
| Out[1]= |  | 
Get the formula:
| In[2]:= | ![FormulaData[ResourceObject["First Knudsen Number"]]](images/e6a/e6ae7d32-f78c-4905-b3f2-ff626af1c776-io-2-i.en.gif) | 
| Out[2]= |  | 
Use some values:
| In[3]:= | ![FormulaData[
 ResourceObject["First Knudsen Number"], {QuantityVariable[
\!\(\*SubscriptBox[\("Kn"\), \("1"\)]\),"KnudsenNumber1"] -> 1, 
  QuantityVariable[
\!\(\*SubscriptBox[\("l"\), \("mfp"\)]\),"MeanFreePath"] -> 
   Quantity[1, "Meters"]}]](images/e6a/e6ae7d32-f78c-4905-b3f2-ff626af1c776-io-3-i.en.gif) | 
| Out[3]= |  | 
 
                 
                