Adding custom particle forces

[p3gamer]

I'm trying to accomplish the same thing but only apply the external force on a button click. I am using an ObiSphericalForceZone (in 2D if that matters). I've duplicated the SimpleFluid and set the atmospheric drag > 0. I've played around with the intensity and turbulence parameters, but I am not seeing any forces being applied ( I even moved the ApplyForcesToActor( ) into the LateUpdate( ) ). Is there an example that uses ObiSphericalForceZone?