Capillarity and Wetting Phenomena: Drops, Bubbles, Pearls, Waves

Hydrodynamic and hydromagnetic stability

This book covers the following topics: recent developments in three dimensional and unsteady turbulence boundary-layer computations; flows far from equilibrium via molecular dynamics; physics of convention-solidification interaction; the continental shelf bottom boundary layer; gravity currents in rotating systems; strange attractors in fluids: another view; eddies, waves, circulation, and mixing: statistical geofluid mechanics; regular and mach reflection of shock waves; ship propellers; coherent structures; the critical layer and stability; general circulation of the oceans; characteristic-based schemes for the euler equations; vortex flows in aerodynamics; steady and unsteady boundary-layer separation; and wind wave prediction.

Annual Review of Fluid Mechanics

Thermal hydraulic phenomena related to small break LOCAs in AP1000

Direct numerical and large eddy simulations are powerful tools for analyses of turbulent flows at low and large Reynolds or Rayleigh numbers in fundamental research. The current status of both methods and recent extensions are compiled. The progress achieved with subgrid scale models and numerics makes the method attractive for investigations in nuclear research and engineering. Applications of both methods of realistic technical flows are discussed. Open problems are mainly related to more general subgrid scale models for large complex containers, to the wall and inlet conditions for high Reynolds number and buoyant flows, and to discretisation schemes for local refinement of spatial resolution. As a classical example for the use of direct simulations, results are presented for a turbulent internally heated horizontal fluid layer. The analysis of the closure terms in the transport equation of the kinetic energy demonstrates major difficulties of the conventional statistical modelling for partially stably stratified convection.

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Direct numerical and large eddy simulations in nuclear applications

Heat transfer correlation for film boiling during quenching of micro-structured surfaces

Thermal-hydraulics phenomena important in modeling and simulation of liquid-fuel molten salt reactors

Neutronics phenomena important in modeling and simulation of liquid-fuel molten salt reactors

Abstract The accurate prediction of the fluid flow mass and the heat transfer process as well as the system response during reflood transients has long been a critical and challenging issue for reactor system safety analyses. Accurate characterization of the flow and energy transport can also significantly facilitate the various system/component design and optimization tasks. In the current study based on the U.S. Nuclear Regulatory Commission/Pennsylvania State University Rod Bundle Heat Transfer (RBHT) reflood experimental data, a comprehensive uncertainty analysis framework is developed using DAKOTA. The developed framework is used to perform an in-depth reflood model validation and verification for the subchannel analysis code COBRA-TF. In the meantime, the artificial intelligence (AI)–based machine learning (ML) model for rod cladding temperature prediction during reflood is also developed and evaluated using the current framework. Key input parametric effects for reflood thermal-hydraulic prediction include the system pressure, inlet liquid temperature/enthalpy, inlet mass flow rate, and average bundle power input. The figure of merit under consideration is the peak cladding temperature variations. It is found in the current study that, while further model improvement is needed, COBRA-TF can predict the correct parametric trends when compared with the RBHT data. On the other hand, it is challenging for the pure AI-based ML models to correctly reflect the parametric trends. Suggestions for future ML model development are provided in the end.

Validation and Uncertainty Quantification of Transient Reflood Models Using COBRA-TF and Machine Learning Techniques Based on the NRC/PSU RBHT Benchmark

Stephen M. Bajorek

Papers

Heat transfer correlation for film boiling during quenching of micro-structured surfaces

Thermal-hydraulics phenomena important in modeling and simulation of liquid-fuel molten salt reactors

Neutronics phenomena important in modeling and simulation of liquid-fuel molten salt reactors

Validation and Uncertainty Quantification of Transient Reflood Models Using COBRA-TF and Machine Learning Techniques Based on the NRC/PSU RBHT Benchmark