# Fluid Density

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hi all am working on a game where aircrafts are simulated using physx library. i want to make it little more realistic that it should take air density in to account. as far as i studied i didnt find any support for such a thing as effect on the body by its surrounding fluid. for now am planning to calculate forces like lift,drag externally(based on its veloity, mass etc..) and provide it to the engine in the form of linear force. the problem with my approach is i cant simulate drag,lift on free falling aerodynamic object. so if i drop a glider from a specific height in my game, it wont start gliding by itself like a real one. i would like to have ur advices on this.

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AFAIK, fluid mechanics is a VERY complex area of study. Full fluid simulations can be very processor intensive and slow. I don't know if GPGPU can speed this up at all, I know that some physics engines have basic fluid mechanics, but not anything aimed toward lift etc.
Any fluid/dynamics buffs feel free to correct me here.
What you could do is simplify the lift of a wing into a spherical precalculated lookup, (this could be GPU accelerated) with the lift on a wing defined for a set of locations around the wing. Wind is defined as the vectors Prevailing_wind and minus airplane_velocity summed together (Minus velocity as the 'wind' is in the opposite direction to that which you are moving). Its then a simple case of lerping between lookups to find the right value. You could even scale the velocity vector by a function of its length and the area 'visible' to increase drag to match terminal velocity, although this may be a bit OTT.
Then again maybe I'm wrong and it is possible to do full sim's on current hardware :P

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