Research for the kawoosh

I've been trying to figure out how to do this effect using particles for a while now, and I still can't figure it out.
I've posted my problem on the 3dmd.net and cgsociety forums to see if anyone can help me with it.
I've also messaged Florian Zender, the lead effects artist at Yager, (creators of Spec Ops - The Line.
Hopefully someone gets back to me soon.