[SarahG]

I have a UDF for a square wave profile for a pressure-inlet zone named ejection which works..
But I noticed it works in a peculiar way. If it says this

pressure = sin(0.52*(t-1.3482)-(5*PI/7));
/* local variables */

if(pressure > 0.75)
{
F_PROFILE(f, thread, position) = 0.5;
}
else
{
F_PROFILE(f, thread, position) = 0.0;
}

It's on for 3/4 of the cycle and off for 1/4 - totally the other way round to what I expected.

In another instance, a UDF to cause pitching of the aerofoil needed an arbitrary pi/2 to get the sense of the pitching right. I also had to rotate the aerofoil in the mesh to the mean angle or else, if was positioned at 0 degrees, it would rotate entirely in the negative quadrant.

I'm running a couple more simulations now, which I think will work as I expect them to. But does anyone know if there is a particular reason for this? Is there a different coordinate system in Fluent?

Appreciate any input, thanks