add examples

Author: haochey

README.md

@@ -37,19 +37,25 @@ MFC has high-level documentation, visualizations, and more on [its website](http
 ## An example
 
 We keep many examples.
-Here's one!
+Here are some of them!
 MFC can execute high-fidelity simulations of shock-droplet interaction (see `examples/3d_shockdroplet`)
 
 <p align="center">
     <img src="docs/res/shockdrop.png" alt="Shock Droplet Example" width="700"/>
 </p>
 
-Another example is the high-Mach flow over an airfoil, shown below.
+This one simulates high-Mach flow over an airfoil, shown below.
 
 <p align="center">
     <img src="docs/res/airfoil.png" alt="Airfoil Example" width="700"/><br/>
 </p>
 
+This one simulates high amplitude acoustic wave through a circular orifice opening, shown below.
+
+<p align="center">
+    <img src="docs/res/orifice.png" alt="Orifice Example" width="700"/><br/>
+</p>
+
 
 ## Getting started