Spectral Element Methods for Liquid Metal Reactors Applications

TL;DR

This paper reviews the spectral element method as implemented in Nek5000, a high-fidelity CFD tool, for simulating liquid metal reactors, emphasizing its applications in turbulence modeling and multiphysics coupling.

Contribution

It provides a comprehensive overview of the spectral element method in Nek5000 and its application to liquid metal reactor simulations, highlighting its versatility and recent developments.

Findings

Nek5000 employs spectral element methods for high-fidelity fluid flow simulations.

The code supports turbulence-resolving techniques like LES and DNS.

Nek5000 is also used for intermediate-fidelity models such as RANS and reduced-order models.

Abstract

Funded by the U.S. Department of Energy, the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program aims to develop an integrated multiphysics simulation capability for the design and analysis of future generations of nuclear power plants. NEAMS embraces a multiresolution hierarchy designing the code suite structure to ultimately span the full range of length and time scales present in relevant reactor design and safety analyses. Advanced reactors, such as liquid metal reactors, rely on innovative component designs to meet cost and safety targets. In order to span a wider design range, advanced modeling and simulation capabilities that rely on minimal assumptions play an important role in optimizing the design. Over the past several years the NEAMS program has developed the integrated multiphysics code suite (thermal-hydraulics, structural analysis and neutronics) SHARP aimed at streamlining the prototyping of such components. For the simulation of fluid flow and heat transfer, SHARP focuses on the high-fidelity end, aiming primarily at turbulence-resolving techniques such large eddy simulation (LES) and direct numerical simulation (DNS). The computational fluid dynamics code (CFD) selected for SHARP is Nek5000, a state-of-the-art highly scalable tool employing the spectral element method (SEM). In this manuscript, to be published in a Von karman institute lecture series monograph on liquid metal reactors, we review the method and its implementation in Nek5000. We also examine several applications. We note that Nek5000 is also regularly employed for intermediate-fidelity approaches such as Reynolds-averaged Navier-Stokes (RANS) and for reduced-order models employing momentum sources or porous media, especially when coupled to neutronics modeling.