hi,
I have a question about a “wind tunnel direction parameter” in smoke object node in DOP. This creates a constant wind effect very naturally lovely, instead of using gasWind Node. Therefore I'd really like to know how this calculation works mathematically. And eventually I want to create a custom wind-tunnel node by a gasVOP or gasWrangle.

I would like to have your answers with short explanation and some mathematical example descriptions like:

@vel = @vel + gasTunnelVelocity ( I am pretty sure this is wrong because this will accelerate every frame)

@vel =max(@v, gasTunnelVelocity)

Please find an attachment file showing the parameter, thank you.

The wind tunnel parameter changes the background (default) and border values for the velocity field. There's no mathematical difference other than not starting from 0 velocity.

>>The wind tunnel parameter changes the background (default)
Yes, basically the parameter exist and control SOPVectorField node(velocity_data) inside of smnokeObject.


>>and border values for the velocity field
I want to know exactly how it define the border and how to change or blend wind velocity. This is because if wind velocity is applied at the first frame only, it's so easy to understand, but at every frame, it does do some calculation and mix operation.