From: owner-ammf-digest@smoe.org (alt.music.moxy-fruvous digest) To: ammf-digest@smoe.org Subject: alt.music.moxy-fruvous digest V14 #4635 Reply-To: ammf@fruvous.com Sender: owner-ammf-digest@smoe.org Errors-To: owner-ammf-digest@smoe.org Precedence: bulk alt.music.moxy-fruvous digest Saturday, July 25 2020 Volume 14 : Number 4635 Today's Subjects: ----------------- Take it with you on vacation, to the country, to the pool or work! ["Fly ] ---------------------------------------------------------------------- Date: Sat, 25 Jul 2020 09:24:09 -0400 From: "Fly Blocker" Subject: Take it with you on vacation, to the country, to the pool or work! Take it with you on vacation, to the country, to the pool or work! http://healthazam.co/gvyHAKH6Z611ul0e1kkFSe0a6YrshQw3qI7n7SVHW0Et3W79 http://healthazam.co/nXtZ98dPfnDez0okU1m6g4nfyZhzwYfUVq19S_4ydgyDnO2m Bernoulli's principle states that there is a direct mathematical relationship between the pressure of a fluid and the speed of that fluid, so if one knows the speed at all points within the airflow one can calculate the pressure, and vice versa. For any airfoil generating lift, there must be a pressure imbalance, i.e. lower average air pressure on the top than on the bottom. Bernoulli's principle states that this pressure difference must be accompanied by a speed difference. Conservation of mass Streamlines and streamtubes around an airfoil generating lift. Note the narrower streamtubes above and the wider streamtubes below. Starting with the flow pattern observed in both theory and experiments, the increased flow speed over the upper surface can be explained in terms of streamtube pinching and conservation of mass. For incompressible flow, the rate of volume flow (e.g. volume units per minute) must be constant within each streamtube since matter is not created or destroyed. If a streamtube becomes narrower, the flow speed must increase in the narrower region to maintain the constant flow rate, to satisfy the principle of conservation of mass. The upper streamtubes constrict as they flow up and around the airfoil. Conservation of mass says that the flow speed must increase as the stream tube area decreases. Similarly, the lower streamtubes expand and their flowrate slows. From Bernoulli's principle, the pressure on the upper surface where the flow is moving faster is lower than the pressure on the lower surface where it is moving slower. This pressure difference creates a net aerodynamic force, pointing upward. Limitations of the simplified explanations As explained below under a more comprehensive physical explanation, producing a lift force requires maintaining pressure differences in both the vertical and horizontal directions, and thus requires both downward turning of the flow and changes in flow speed consistent with Bernoulli's principle. The simplified explanations given above are therefore incomplete because they define lift in terms of only one or the other. And depending on the details, they have other shortcomings as well. The explanation based on flow deflection and Newton's laws is correct but is incomplete. It does not explain how the airfoil can impart downward turning to a much deeper swath of the flow than it actually touches. Further, it doesn't explain how the pressure differences in the horizontal direction are sustained. That is, it leaves out the Bernoulli part of the interaction ------------------------------ End of alt.music.moxy-fruvous digest V14 #4635 **********************************************