Simultaneous Solution of Neutronics/Thermal-Hydraulic Coupled System Based on Nonlinear Preconditioned JFNK Method

The Jacobian-free Newton-Krylov method is utilized to solve the Neutronics/ Thermal-Hydraulic coupled system in nuclear reactors. Nonlinear preconditioning is employed to avoid the nonlinear residuals, take full advantage of the original codes and couple these codes as black boxes. The basic property of nonlinear preconditioning is analyzed. The difference and connection between nonlinear and linear preconditioning are presented. The numerical results show that the nonlinear/linear preconditioned JFNK methods are more efficient than the traditional method for 3 cases of a 2-D simplified reactor model. Further more, the computational efficiency of linear preconditioned JFNK is better than that of nonlinear preconditioned JFNK.