A hybrid incremental projection method for thermal-hydraulics applications

127

VERA, the Virtual Environment for Reactor Applications, is the system of physics capabilities being developed and deployed by the Consortium for Advanced Simulation of Light Water Reactors (CASL). CASL was established for the modeling and simulation of commercial nuclear reactors. VERA consists of integrating and interfacing software together with a suite of physics components adapted and/or refactored to simulate relevant physical phenomena in a coupled manner. VERA also includes the software development environment and computational infrastructure needed for these components to be effectively used. We describe the architecture of VERA from both software and numerical perspectives, along with the goals and constraints that drove major design decisions, and their implications. We explain why VERA is an environment rather than a framework or toolkit, why these distinctions are relevant (particularly for coupled physics applications), and provide an overview of results that demonstrate the use of VERA tools for a variety of challenging applications within the nuclear industry.

Section: Thermal/hydraulicsmentioning

confidence: 99%

“…The solution algorithm used in Hydra-TH is based on a second-order incremental projection algorithm [20]. Projection methods are the most computationally efficient solution method available for solving the time-dependent Navier-Stokes equations.…”

Section: Hydra-thmentioning

confidence: 99%

The Virtual Environment for Reactor Applications (VERA): Design and architecture

Turner

Clarno

Sieger

et al. 2016

127

“…197], "Thus, all algorithms based on finite-volume differencing have a truncation term in the form of the divergence of a subgrid-scale model." From this perspective, the ILES capabilities in Hydra-TH derive from the high-resolution monotonicity-preserving advective treatment as described in Christon, et al [18].…”

Section: Implicit Large-eddy Simulationmentioning

confidence: 99%

Large-eddy simulation, fuel rod vibration and grid-to-rod fretting in pressurized water reactors

Christon

Bakosi

et al. 2016

Self Cite

Grid-to-rod fretting (GTRF) in pressurized water reactors is a flow-induced vibration phenomenon that results in wear and fretting of the cladding material on fuel rods. GTRF is responsible for over 70% of the fuel failures in pressurized water reactors in the United States. Predicting the GTRF wear and concomitant interval between failures is important because of the large costs associated with reactor shutdown and replacement of fuel rod assemblies. The GTRF-induced wear process involves turbulent flow, mechanical vibration, tribology, and time-varying irradiated material properties in complex fuel assembly geometries. This paper presents a new approach for predicting GTRF induced fuel rod wear that uses high-resolution implicit large-eddy simulation to drive nonlinear transient dynamics computations. The GTRF fluid-structure problem is separated into the simulation of the turbulent flow field in the complex-geometry fuel-rod bundles using implicit large-eddy simulation, the calculation of statistics of the resulting fluctuat-* Corresponding author.

“…Hydra-TH [1-9] refers to the hybrid finite-element / finite-volume incompressible / low-Mach flow solver in the Hydra toolkit being used for thermal-hydraulics ("TH") applications for the Consortium for Advanced Simulation of Light Water Reactors ("CASL") [10]. Hydra-TH features a recently developed second-order, hybrid finite-element / finite-volume, incremental projection algorithm for time-dependent incompressible viscous flows [11]. The algorithm circumvents the 2 usual div-stability constraints, i.e., does not require explicit treatment of troublesome pressure modes using Rhie-Chow interpolation or a pressure-stabilized Petrov-Galerkin formulation.…”

Section: Introductionmentioning

confidence: 99%

“…The use of a co-velocity and high-resolution advection scheme with consistent edge-based treatment of viscous/diffusive terms yields a robust algorithm for a broad spectrum of incompressible flows. A detailed description of the numerical algorithms, implementations, and basic verification and validation problems has been presented in the work of Christon et al [11].…”

Section: Introductionmentioning

confidence: 99%

Assessment of a hybrid finite element and finite volume code for turbulent incompressible flows

Xia

Wang

Luo

et al. 2016

Self Cite

Hydra-TH is a hybrid finite-element / finite-volume incompressible / low-Mach flow simulation code based on the Hydra multiphysics toolkit being developed and used for thermal-hydraulics applications. In the present work, a suite of verification and validation (V&V) test problems for Hydra-TH was defined to meet the design requirements of the Consortium for Advanced Simulation of Light Water Reactors (CASL). The intent for this test problem suite is to provide baseline comparison data that demonstrates the performance of the Hydra-TH solution methods. The simulation problems vary in complexity from laminar to turbulent flows. A set of RANS and LES turbulence models were used in the simulation of four classical test problems. Numerical results obtained by Hydra-TH agreed well with either the available analytical solution or experimental data, indicating the verified and validated implementation of these turbulence models in Hydra-TH. Where possible, some form of solution verification has been attempted to identify sensitivities in the solution methods, and suggest best practices when using the Hydra-TH code.