Coupling one-dimensional user code and STAR-CCM+ for simulation of rolling conditions in a rod bundle channel

Abstract The numerical simulation of the one-dimensional user code and the three-dimensional software STAR-CCM + coupling is performed on a natural circulation loop of a 3 × 3 rod bundle channel under rolling conditions. The coupling simulation method in this paper utilizes our one-dimensional user code, which is compiled and linked to generate a dynamic link library (DLL). The DLL is then imported into STAR-CCM+, so as to realize the coupling simulation of the one-dimensional user code and the three-dimensional Computerized Fluid Dynamics (CFD) code. In the one-dimensional user code, the mathematical model under rolling conditions is established to simulate the natural circulation loop except for the rod bundle channel. Adding a rotational motion to the STAR-CCM + enables a rolling simulation of the rod bundle channel. In order to compare the rationality of the coupled simulation, this paper also reports on the results carried out in an uncoupled simulation to study the rod bundle channel under the rolling conditions. The coupled simulation is a simulation that can be performed independently of an experiment, but the uncoupled simulation is not. That fact further demonstrates the wide applicability of the coupled simulation. The flow velocity and pressure drop characteristics in the 3 × 3 rod bundle channel are investigated. The results show that the coupled simulation method can predict the flow characteristics of the rolling rod bundle channel in the natural circulation loop well. The paper describes the coupling method in detail, which can make a foundation for future coupling research.