The thermal-hydraulic behavior of complex, large-scale systems such as nuclear reactors is the product of a wide range of fluid-mechanics phenomena. In principle, these phenomena can be modeled directly (at least for single-phase flows) through the direct simulation of the Navier-Stokes equations. However, such a “reactor-scale” direct simulation approach remains infeasible today, given that such a model would need to span a range of scales. Where code developments up to today focused on resolving issues at a specific scale, challenges in which complex phenomena at various scales interact require a different approach. Some system thermal-hydraulic codes nowadays allow three-dimensional modeling. However, computational fluid dynamics codes are superior to that respect. On the other hand, such codes are computationally too expensive to allow modeling a complete system. To overcome this problem, different codes covering multiple scales can be coupled in a multiscale simulation approach. This chapter introduces this multiscale simulation concept, presents modeling choices to be made, explains the challenges, and provides guidelines. Finally, some examples of application of such approaches are shown.
Chapter 7 - Multi-scale simulations of liquid metal systems
Nicola ForgioneWriting – Review & Editing
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2019-01-01
Abstract
The thermal-hydraulic behavior of complex, large-scale systems such as nuclear reactors is the product of a wide range of fluid-mechanics phenomena. In principle, these phenomena can be modeled directly (at least for single-phase flows) through the direct simulation of the Navier-Stokes equations. However, such a “reactor-scale” direct simulation approach remains infeasible today, given that such a model would need to span a range of scales. Where code developments up to today focused on resolving issues at a specific scale, challenges in which complex phenomena at various scales interact require a different approach. Some system thermal-hydraulic codes nowadays allow three-dimensional modeling. However, computational fluid dynamics codes are superior to that respect. On the other hand, such codes are computationally too expensive to allow modeling a complete system. To overcome this problem, different codes covering multiple scales can be coupled in a multiscale simulation approach. This chapter introduces this multiscale simulation concept, presents modeling choices to be made, explains the challenges, and provides guidelines. Finally, some examples of application of such approaches are shown.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
