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FREESTREAM - Freestream conditions

 FREESTREAM {STATIC | TOTAL} [CONDITIONS] M P T α β

This keyword allows input of freestream flow conditions. The user-specified parameters are defined as:

M Mach number Static or total pressure (psi), depending on the STATIC | TOTAL keyword Static or total temperature (°R), depending on the STATIC | TOTAL keyword Angles of attack and sideslip (degrees)

Note that, if U is the freestream velocity magnitude, α and β are related to the ("downstream", "up", and "sidestream") aeroaxis velocity components by:

 vds = U cos β cos α vup = U cos β sin α vss = U sin β
Which Cartesian components these correspond to depends upon how the aerodynamic axes have been assigned. Using the default set of aerodynamic axes ("downstream","up","out"=+x,+y,+z), α is rotation about the z-axis and β is rotation about the y-axis. Note that the "sidestream" velocity component is always in the "downstream" cross "up" direction, but the "out" direction used for force integration may have the opposite sign.

 FREESTREAM REYNOLDS [CONDITIONS] M Re T α β

In this alternate formulation, the freestream static pressure will be computed from the specified static temperature and Reynolds number. Re is based on the freestream velocity U and should be per unit grid length. At present, this form may only be used with perfect gases and certain viscosity models. The code will stop with an error if it is unable to proceed.