# Tag Info

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I think I figured it out. Bernoulli's assumption is incompressible flow. The equation yielding from momentum conservation always holds. When velocity is low (incompressibility holds), the two equations yields similar results.

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The factor $\frac 12$ comes from the relation $\vec v \cdot\nabla \vec v = \nabla \frac{\vec v^2}{2} + (\nabla\times\vec v)\times \vec v$ in the momentum conservation equation $$\rho \left(\frac{\partial \vec v}{\partial t}+\vec v \cdot\nabla \vec v\right)=\vec g-\nabla p$$ (Sorry to post this as an answer, but I can't comment your post yet because of ...

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There's two ways to answer this. The first way is the intellectually precise way, modeling the pump, the water traveling through the pipe and nozzle, the dispersion of the water as it rises influenced by air and surface tension, the air drag on each blob of water as the column separates, the impacts of the falling water on the still-rising column, etc. etc. ...

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if objects have a blunt form factor and the fluid have a large enough Reynolds number in order to produce turbulence behind the object. The equation is where, the drag force = mass density * flow velocity relative to the object * reference area * drag coefficient and we know, so, you should write all the drag coefficient and Reynolds number as ...

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According to this Wikipedia article and other on-line sources (search for "nascar drafting"), the effect is noticeable in other auto sport disciplines. The front car does notice reduced draft, and it's enough to make two cars close together go faster than one car alone: On the faster speedways and superspeedways used by NASCAR, ARCA, and at one time ...

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The rigid bodies whose aerodynamics are most richly understood are airplanes. Most airplanes are constructed to be aerodynamically stable: If you turn off the engines and trim the control surfaces appropriately once and for all, the plane will glide stably forward at a shallow angle of descent until it reaches the ground -- without any need for movement of ...

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An object will orientate itself with its centre of mass below its centre of pressure. Thus there is a right way and a wrong way to rig a parachute. Rig the parachute with strings all around so that your mass will cause it to spread out horizontally, and you will live. Attach yourself only to one edge of the parachute, and it will orientate itself ...

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The answer to this question is "hard" in the sense that a general object falling from general initial conditions may or may not reorient into a lowest drag orientation. However, one can make some educated guesses by comparing the locations of the center of drag (more generally, the center of pressure) and the center of mass of the object. Consider one ...

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It depends on the object's shape, mass distribution, and rigidity. If the object's center of mass is directly leading its center of aerodynamic pressure while falling, it will be stable in that orientation. If the object's centers of mass and pressure are coincident, or if the center of mass lies behind the center of pressure, it won't be stable in that ...

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No (see falling leaves), and it's more likely to be quite the opposite since the the aerodynamic orientation is generaly unsteady and a small tilt is prone to make the orientation worser and worser.

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A crude model of the UTE is used simulate the pressure field created by the car as it travels through atmospheric air. We must determine the pressure in truck bed because it applies force on the surfboard. The car travels at a constant $60 ~\text{mph}$ (an arbitrary, worst-case value). UPPER: The velocity profile of air flowing around the car. ...

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The ground effect that is used in the F1 cars make a large pressure differential between the upper and the lower board surfaces. If the air can flow freely bellow the surfboard it will fly away, otherwise it is 'glued' to your truck. Be precautious and lock it mechanically. EDIT ADD. The board behaves like a wing flying near the ground. Above it's upper ...

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Sorry but surf boards do fly out. You may not have experienced it personally but keep doing it the way you are and you are bound to experience it. If you are thinking that as the velocity of the air travels over car it is some how holding the boards in you are incorrect. Check out this article http://www.gcdataconcepts.com/carairflow.html "Actually the ...

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I would simply point out that in other cars, as speed increases, the amount of rubber on the road decreases. This helps to provide a dampening effect, to keep the car from going airborne. It isn't perfect, but in most instances, your average commuter driving a Ford Escape doesn't reach the necessary velocity to become airborne. On a tenuously-related ...

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