Step 4 (out of 6) from my blog on How to create a Flow diagram with a circular Twist in which the arcs have already been pulled apart, but the chords themselves not yet.
An example based on actual data can be found here
Modified http://d3js.org/d3.v3.js to a secure url
Modified http://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js to a secure url
https://d3js.org/d3.v3.js
https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js