Can lift occur if air is flowing over an object, but not und

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  p1Can lift occur if air is flowing over a fixed-shape object, but no air is flowing under any part of the object? Maybe the object is the top half of a wing that's glued to the ground, or the object is dome-shaped, or some other shape. Maybe the object doesn’t actually rise or move, but when air flows over it, it exerts less weight on the ground.p2
  p1Yes. This jar of paint weighs 34.8 g, but only 32.6 g to 33.4 g when a fan blows at it. The reduction of weight persisted when I repeated the experiment with a hodgepodge of baffles made from CD jewel cases and Post-Its to prevent any air leakage under the scale's sensor plate. Others can easily replicate these results.p2p1Per FlanMan's comment, without the fan, I also tried pushing the jar horizontally with a very sharp pencil, like a pool cue to avoid imparting vertical force.No matter where I put the jar on the scale,no matter which way I pushed relative to the scale,no matter how high the pencil tip touched the jar,by the time the jar moved, the scale's report changed no more than -0.1 g to +0.2 g, and usually increased: it got heavier instead of producing lift.(The fan wasn't nearly strong enough to move the jar. High volume, low pressure, in paint sprayer parlance.)p2p1So the horizontal component of the fan's force accounts for at most 1/7 to 1/10 of the effect. One could throw some statistics at this, or a milligram-accurate jeweler's scale, but more confidence would come from trying this in a proper wind tunnel whose load cell is quite independent of the air flow.p2p1p2
  p1Yes.Bernoulli end effectors are used in industrial applications to pick up items without physical contact using this principle.Example:
  p1Yes, because the still air under the object has (by Bernoulli) a higher pressure than the moving air above.That's why, in high winds, entire roofs are sometimes detached from houses...p2
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