I did actually google this and didn't find anything definitive - I am sure the smart cookies of Geekzone can chime in!
When using your heat pump/AC split-unit to cool your house, what is the optimal setting and angle for the louver/blades?
My theory is that given hot air rises, one should aim it almost out in a straight line to cool the hot air at the top of the room which should cool and sink, drawing the warmer air upwards and creating a sort of cooling convection. This way, although you don't feel the cold draft of air directly on yourself, it should get the room to an overall pleasing temperate fairly quickly and maintain it efficiently.
...this may well be utter nonsense, so I throw it to you guys: Swing Louver? Fixed? Pointing Up/Down/middle?