Thermal hydraulics modeling and simulation at ORNL relies on a combination of custom code development, leveraging of open source software, and extension of commercial codes. These codes span a range of resolutions, including:
• Direct numerical simulation (DNS) capabilities that provide fully resolved numerical solutions of the Navier-Stokes equations
• Large eddy simulation (LES) capabilities that fully resolve large scale turbulence structures and use engineering models to describe structures smaller than the computational mesh elements
• Reynolds-averaged Navier–Stokes (RANS) simulation capabilities that rely on engineering models to describe all turbulence • Advanced mesoscopic lattice Boltzmann method (LBM) for simulating turbulent flows
• Multiphase CFD using the level set and volume of fluid methods
• Subchannel models which provide reduced order lumped parameter representations of thermal hydraulic phenomena
• Lumped thermal-hydraulics component models to simulate an entire nuclear system including the balance of plant