Quote:
Originally Posted by freebeard
In 3D graphics, Blender specifically, you have Displacement, which acts normal to the surface, and Vector Displacement, which can act at any angle to the surface. It's used to procedurally generate overhangs.
Assuming the air molecules adjacent to the surface are immobile [locally], displaced air molecules up through the boundary layer act at a resultant angle. Therefore, there exist shear forces as well as normal forces. And the vehicle is 'stuck' in the hole left by activities in the atmospheric shell. Shapes it's own destiny, as it were.
Am I provably wrong again?
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For laminar flow, you can presume that any particular streamline filamant would displace normal to the 'wall', 'boundary,' however a vortice 'particle's' spatial location will vary temporally as it spirals from origin,to final position, perhaps hundreds of meters behind the vehicle, where, as with wake turbulence, viscous attrition has robbed it of all kinetic energy.
Only the air immediately adjacent to the 'wall' is at rest. Everything above, within the TBL is turbulent, with violent shear / mixing as it's bombarded by laminar flow at its interface. And only if separation is nor occurring.
Local atmospheric pressure will maintain constant normal force, surface friction heating will be robbing around 12% of all energy, if there's zero separation, then that's all the air loses. With separation, the induced turbulence wastes all its kinetic energy to atmospheric heating.You can never recover it ( 2nd Law of Thermodynamics).