Re: How do you calculate uplift/downlift force on an object from winds?

Greetings:

Your question is related to the science of Fluid Dynamics. Fluid Dynamics 
has two branches. The first branch addresses the flow of incompressible 
fluids such water and is called Hydrodynamics. The second branch addresses 
the flow of compressible fluids such as air and is called Aerodynamics. 
Aerodynamics has been one of the most difficult sciences to model 
mathematically and there is a long history of the experimental measurements 
of wind flow over hundreds of standard solid bodies such as cubes, 
cylinders, cones, spheres and the aerodynamic surfaces used to design 
aircraft. This is why wind tunnels and flight testing are still in use for 
the design of aircraft etc. 

Mathematical models based on experimental measurements are called empirical 
formulas and usually you must match your problem to one or more of the 
standard body empirical models. Today aerodynamic modeling of complex shaped 
bodies is usually conducted on super computers and hundreds of hours of 
running time are required to model each shape.

NASA’s Aeronautics Learning Laboratory for Science Technology and Research  
(ALLSTAR) web site covers these concepts and adds much more detail. This 
site is enhanced with animated diagrams using software that you can quickly 
download on the web site.
 http://www.allstar.fiu.edu/

The ALLSTAR web site has three levels of complexity:

Level 1 - Intended primarily for middle / junior high school students.
Level 2 - Intended primarily for junior high / high school students.
Level 3 - Intended primarily for high school / lower division university 
students.

Engineers often use simple models of airflow on standard bodies to calculate 
the forces of wind on buildings, bridges, etc and often the principle of 
conservation of momentum is used. Typically a safety factor of 2 or 3 times 
will be added to the results of these calculations.

There are examples of these types of calculations, which are similar to 
your questions, in the Mad Science archives at:

 here
 and 
 here

Enjoy the ALLSTAR web site
Your Mad Scientist
Adrian Popa