[AndyR]

Folks,
I generally use two classes of codes. High speed codes like CFD++, Vulcan etc which are described as density based solvers. And incomprehensible codes such as Star-CCM and Fluent, described as pressure based solvers.


Now Fluent and Star both have "coupled solvers" which allow them to solve problems where one would more typically use a density based code.


And in a similar fashion one can invoke "preconditioning" in the high speed tools which allow them to solve problems down as far as Mach 0.2, or so it is claimed


My experience with both these approaches is so simply use the appropriate tool if at all possible, and that running CFD++ to do a subsonic pipe network would or running Fluent to run a Scramjet are simply exercise in frustration.



So to my question. I doubt highly that the density based codes with a lot of preconditioning are actually numerically equivalent to a pressure based solver. IE the equations are descritized differently and solved differently.


Are the numerics for a "coupled" solver in a code like Fluent or Star really that similar to the numerics for a density based solver such as CFD++



Thanks
Andy