Atwood Number
The Atwood number is a dimensionless number in fluid dynamics used in the study of hydrodynamic instabilities in density-stratified flows.
The Atwood number equals the ratio of the difference in mass densities to their sum.
Formula
![Copy to Clipboard QuantityVariable["A", "AtwoodNumber"] == (QuantityVariable[Subscript["ρ", "1"], "MassDensity"] - QuantityVariable[Subscript["ρ", "2"], "MassDensity"])/(QuantityVariable[Subscript["ρ", "1"], "MassDensity"] + QuantityVariable[Subscript["ρ", "2"], "MassDensity"])](https://www.wolframcloud.com/objects/resourcesystem/marketplacestorage/resources/82c/82cc1389-baab-4927-999b-82a4ebba0653/Webpage/FormulaImage.png)
| symbol | description | physical quantity | 
|---|---|---|
| A | Atwood number | "AtwoodNumber" | 
| ρ1 | fluid density | "MassDensity" | 
| ρ2 | fluid density of lighter fluid | "MassDensity" | 
Forms
Examples
Get the resource:
| In[1]:= | ![ResourceObject["Atwood Number"]](images/82c/82cc1389-baab-4927-999b-82a4ebba0653-io-1-i.en.gif) | 
| Out[1]= |  | 
Get the formula:
| In[2]:= | ![FormulaData[ResourceObject["Atwood Number"]]](images/82c/82cc1389-baab-4927-999b-82a4ebba0653-io-2-i.en.gif) | 
| Out[2]= |  | 
Use some values:
| In[3]:= | ![FormulaData[ResourceObject["Atwood Number"], {QuantityVariable[
\!\(\*SubscriptBox[\("\[Rho]"\), \("2"\)]\),"MassDensity"] -> 
   Quantity[1200, ("Kilograms")/("Meters")^3]}]](images/82c/82cc1389-baab-4927-999b-82a4ebba0653-io-3-i.en.gif) | 
| Out[3]= |  | 
 
                 
                