On the Numerical Approach for Simulating Thermal Hydraulics under Seismic Condition

Authors: Tadashi Watanabe

Abstract:

The two-phase flow field and the motion of the free surface in an oscillating channel are simulated numerically to assess the methodology for simulating nuclear reacotr thermal hydraulics under seismic conditions. Two numerical methods are compared: one is to model the oscillating channel directly using the moving grid of the Arbitrary Lagrangian-Eulerian method, and the other is to simulate the effect of channel motion using the oscillating acceleration acting on the fluid in the stationary channel. The two-phase flow field in the oscillating channel is simulated using the level set method in both cases. The calculated results using the oscillating acceleration are found to coinside with those using the moving grid, and the theoretical back ground and the limitation of oscillating acceleration are discussed. It is shown that the change in the interfacial area between liquid and gas phases under seismic conditions is important for nuclear reactor thermal hydraulics.

Keywords: Two-phase flow, simulation, seismic condition, moving grid, oscillating acceleration, interfacial area

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1071069

References:

[1] K. Amano, R. Iwano and Y. Sibata, "Three-dimensional analysis method for sloshing behavior and its application to FBRs," Nucl. Eng. Des., Vol.140, 1993, pp. 297-308
[2] Y. W. Chang, D. C. Ma, J. Gvildys and W. K. Liu, "Seismic analysis of LMR reactor tanks," Nucl. Eng. Des., Vol. 106, 1988, pp. 19-33.
[3] M. Hirano and T. Tamakoshi,, "An analytical study on excitation of nuclear-coupled thermal hydraulic instability due to seismically induced resonance in BWR", Nucl. Eng. Des., vol. 162, 1996, pp. 307-315.
[4] A. Satou, Neutoron-coupled thermal hydraulic calculation of BWR under seismic acceleration, Proc. Joint Int. Conf. on Supercomputing in Nucl. Applications and Monte Carlo 2010.
[5] D., Liu and P., Lin, A numerical study of three-dimensional liquid sloshing in tanks, J. Comp. Phys. 227, 2008, pp. 3921-3939.
[6] O., Curadelli,, D., Ambrosini, A., Mirasso, and M. Amani,, Resonant frequencies in an elevated spherical container partially filled with water:FEM and measurement, J. Fluids and Struct. 26, 2010, pp. 148-159.
[7] M. Sussman, M. and P. Smereka,, Axisymmetric free boundary problems. J. Fluid. Mech. 341, 1997, pp. 269-294.
[8] C.W. Hirt, A. A. Amsden, and J.L. Cook, An Arbitrary Lagrangian-Eulerian Computing Method for All Flow Speeds. J. Comp. Phys. 14. 1974, pp. 227-253.
[9] Y. C. Chang, T. Y. Hou, B. Merriman, and S. Osher, A level set formulation of Eulerian interface capturing methods for incompressible fluid flows, J. Comp. Phys. 124, 1996, pp. 449-464.
[10] T.Watanabe, "Simulation of sloshing behavior using moving grid and body force methods," World Academy of Science, Engineering and Technology, 79, 2011, pp.638-643
[11] T.Watanabe, "Numerical simulation of droplet flows and evaluation of interfacial area," ASME J. Fluids Engineering, 124, 2002, pp576-583.