Status of development, validation, and application of the 3D CFD code GASFLOW at FZK

The CFD code GASFLOW provides a finite volume solution of the 3D Navier-Stokes equations on a staggered mesh with either Cartesian or cylindrical coordinates. GASFLOW is a best-estimate tool for the characterization of local phenomena in containment thermal-hydraulics, such as pressurization and hydrogen distribution. Examples of such local 3D phenomena include circulation patterns; flow stratification; hydrogen distribution, mixing and stratification; condensation and heat transfer to structures with an option for heat transfer by radiation transport. The new model developments and validations after the release of version 2.0 of GASFLOW in 1998 are summarized. Emphasis is put on the application of GASFLOW to reactor safety problems. An overview of the different GASFLOW applications to analyze steam/hydrogen release and distribution in complex 3D containment geometries is given and generic findings from these 3D CFD simulations are summarized. (author)