Dear CalculiX Users,
there are basically two implementations of the Navier-Stokes equations in CalculiX: one based on Finite Volumes (following the approach described in the book by Moukalled, Mangani and Darwish: the Finite Volume Method in Computational Fluid Dynamics) and one based on the Finite Element Method (following the approach described in the book by Zienkiewicz, Taylor and Nithiarasu: the Finite Element Method for Fluid Dynamics, i.e. the CBS - Characteristic Based Split method). Both are in an experimental state. Turbulence is not active yet. Right now, I am focussing on the CBS-Method, since I have the impression that it is more stable. The theory for both methods is described in the CalculiX User’s Manual, small examples can be found in the standard test suite (look for the parameter CFD in the input deck) and large examples in the dedicated fluid test suites.