queries on M.Peric's example code
 

in the codes of Computational methods for fluid dynamics, density sets as 1, and viscosity is equal to 0.001. So what kind of material does it delegate? water (density=1000, viscosity=0.001), or Air (density=1.29, viscosity=0.000001). the corresponding code can be downloaded from springe's ftp

ftp://ftp.springer.de/pub/technik/peric/

Re: queries on M.Peric's example code
 

The beauty of CFD, comparing to the experiment, is that you can specify any property values such as density and viscosity to the fluid. Let's say for a flow in pipe, Reynolds number determines the flow being laminar or turbulent. Re=(density*velocity*diameter/Viscosity). By adjusting density and/or viscosity, you can achieve desirable Re without changing velocity.

Re: queries on M.Peric's example code
 

It solves the non-dimensional Navier-Stokes equations of Reynolds number=1000 for any fluids. If you read the Patankar's book, there is a section explaining this kind of treatment.