CFD-introduction

For the coolants envisaged in innovative nuclear systems, usually, experiments are very expensive, and detailed measurements of flow and temperature fields are complex or even impossible. To this respect, computational fluid dynamics (CFD) plays an important role in the prediction of various (complex) flow and heat transport characteristics. Hence, CFD becomes an attractive and complementary practice used in the design and evaluation process of innovative nuclear systems. In general, CFD covers a broad field that is often categorized by how the turbulence is modeled or resolved. In the realm of innovative reactor systems, various methods of CFD are adopted and successfully being used. These methods are depicted in Fig. 6.1. Short descriptions of these methods are given in the following sections. What all these methods have in common is that they solve the governing conservation equations of fluid dynamics with respect to mass, momentum, and energy that can be found in all major textbooks concerning fluid dynamics (e.g., Wilcox, 2006). Even though it is recognized that relevant liquid-metal flows for nuclear applications may include free surface and dispersed two-phase modeling, incompressible flow phenomena, the scope of this book is limited to single-phase incompressible flows that remain the key issue in nuclear liquid-metal applications.