A finite volume approach for 3D two phase flows in tube bundles: The 'THYC' code

EDF is developping a new 3 D computer code, at first for PWR's and LFMBR's core thermal-hydraulic calculations and in a second place, for more general applications of flows in tube bundles. This paper describes the physical model used in THYC (4 partial differential equations, closure relationships specific of tube bundle geometries) then numerical solution method (space and time discretization, solution algorithm). Finally, 3 validation calculations will be presented concerning a tube and shell heat exchanger, a LMFBR fuel assembly in natural, mixed and forced convection, and a lower part of a PWR steam generator. (orig./DG)