EnginSoft - CAE Conference Abstracts

EnginSoft International Conference 2011
CAE Technologies for Industry

Comparison of Hydrodynamic Mass for CFD-coupled Analyses

Valtorta Davide - CADFEM Swisse (Switzerland)
Lemcke Claes - IMI Nuclear (Switzerland)
Sabbagh Pascal - CADFEM Swisse (Switzerland)

Abstract

Subject of this investigation is the structure used to store exhausted fuel bars in a nuclear power plant. The structure consists of a series of racks (4x5 elements) and is immersed in a water pool. The response of the structure to an earthquake signal has to be assessed. In order to do this, the fluid structure interaction between the rack and water pool must be numerically simulated.
The interaction between the racks and the fluid can be investigated using two different approaches:

(i) a full FSI computation, i.e. a CFD simulation coupled with a structural FE calculation.
(ii) a simplified approach with hydrodynamic masses to simulate the interaction between the structure and the fluid in a FE analysis. Following this approach, the addition of hydrodynamic masses to the FE model of the rack leads to a faster calculation of the motion of the structure subjected to an earthquake signal.

This work aims first at determining the hydrodynamic mass used for the coupling between the racks and pool in the approach (ii) in order to achieve results similar to the fully coupled mechanical – CFD calculation (i). A further investigation using a FSI (Fluid Structure Interaction) computation has been carried out in order to determine the displacement of the structure in the most correct way. Finally, a comparison between the two methods is proposed in order to assess the correctness of the result obtained with the simplified approach.