This example takes bjtucker‘s block: Bounded Force Layout - force rank by group and swaps out the dataset, showing energy flows from source to use.
This example also adds a Simple D3 tooltip. Hat tip to biovisualize for that bl.ock.
See another view of this energy flow data at the bl.ock Sankey Particles - Transparent Links
README.md from the original bl.ock
This D3 example shows how to constrain the position of nodes within the rectangular bounds of the containing SVG element. As a side-effect of updating the node’s cx and cy attributes, we update the node positions to be within the range [radius, width - radius] for x, [radius, height - radius] for y. If you prefer, you could use the each operator to do this as a separate step, rather than as a side-effect of setting attributes.
Wrote the each operator step described above, but used tick to settle groups into separate ranks. -bjtucker