1. NAME AND TITLE
A Lagrangian-based computational fluid dynamics code for nuclear thermal hydraulics
and safety applications.
SOPHIA code is mainly a solver program. Therefore, it requires a preprocessor
and a postprocessor for data analysis.
script can be used for input generation. For postprocessing, the results can be
using ParaView since they are formatted in *.vtk.
University, Gwanak-ro 1, Gwanak-gu, Seoul, South Korea.
Through the OECD Nuclear Energy
Agency Data Bank, Issy-Les Moulineaux, France.
3. CODING LANGUAGE AND COMPUTER
on a LINUX or UNIX Operating System
RSICC ID: C00857MNYCP00;
NEADB identifier is NEA-1911/01
4. NATURE OF PROBLEM SOLVED
methods used in nuclear safety analyses are generally mesh-based (or
grid-based), such as the finite difference method (FDM), finite element method
(FEM), and finite volume method (FVM). These mesh-based methods have a long
history and are thus very mature both mathematically and numerically. Based on
their robustness and efficiency, they dominate the CFD field and have been used
in many applications, for which these methods produce very accurate results. Mesh-based
methods are generally good for confined computational domains and computation in
which the boundaries and interfaces do not move. However, they may not be the
most efficient for modeling highly nonlinear deformation or interface regions,
which are often involved in the severe accident and natural disasters related
to nuclear power plants. Because of this, a multiphysics smoothed-particle
hydrodynamics (SPH) code framework, SOPHIA, was recently developed at Seoul
National University (SNU) that focuses on key thermal hydraulics and
safety-related phenomena in nuclear reactor systems. SPH is one of the most
well-known Lagrangian methods; it can handle various types of physics extensively
because of its simplicity and ease of expressing and solving mathematical
equations. SOPHIA is written in C++ and is parallelized using graphics
processing units. Like other conventional CFD analysis codes, the applications
of SOPHIA are mainly for fundamental thermal hydraulics, multiphase flow,
severe accidents, natural disasters, and so on for various nuclear reactor
types. Thus, the main physics behind this code include (1) fluid flow, (2) heat
transfer, (3) turbulence, (4) melting/solidification, (5) multiphase, (6)
natural convection, and (7) diffusion. However, in principle, the SOPHIA code
can be easily extended to and is well suitable for other phenomena with some
necessary modifications to the equation of state (EOS) and the physical models.
5. METHOD OF SOLUTION
The SOPHIA code is
based on SPH, which is a meshless numerical method. It solves mass, momentum, and
energy conservations with the EOS and physical models in multidimensional space
and time (2D/3D). The basic mathematical equations are quite similar to
conventional CFDcode, except that the equations are solved in a Lagrangian
6. RESTRICTIONS OR LIMITATIONS
There are no limitations
of the number of particles (the size of the problems) if sufficient GPU memory
is available. For a single GPU, the maximum number of particles is 10 to 15
7. TYPICAL RUNNING TIME
The typical run
time highly depends on the sizes and types of problems being solved. Lagrangian‑based
numerical methods generally require a large amount of computational time. It
may take a couple of minutes to a couple of weeks.
8. COMPUTER HARDWARE REQUIREMENTS
parallelized using GPUs. Therefore, to run this code, a GPU card should be
installed with the CUDA library.
9. COMPUTER SOFTWARE REQUIREMENTS
The current SOPHIA
code runs in a Linux (Ubuntu) environment. However, a Windows version can be
generated with some modifications, if required.
§ Park, S.H., Jo, Y.B., Kim, E.S., “Development of
Multi-GPU-Based Smoothed Particle Hydrodynamics Code for Nuclear
Thermal-hydraulics and Safety: Potential and Challenges,” Frontiers in
Energy Research, Vol. 8, 2020.
§ Jo, Y.B., Park, S.H., Choi, H.Y., Jung, H.W., Kim, Y.J.,
Kim, E.S., “SOPHIA: Development of Lagrangian-based CFD Code for Nuclear
Thermal-Hydraulics and Safety Applications,” Annals of Nuclear Energy,
Vol. 124, pp. 132–149, 2019.
§ Park, S.H., Choi, T.S., Choi, H.Y., Jo, Y.B., Kim, E.S., “Simulation
of a Laboratory-scale Experiment for Wave Propagation and Interaction with a
Structure of Undersea Topography Near a Nuclear Power Plant using a
Divergence-Free SPH,” Annals of Nuclear Energy, Vol. 122, pp. 340–351,
§ Park, S.H., Jo, Y.B., and Kim, E.S., “High Resolution 3-D
Simulation of Melt Jet Break-up Phenomenon using Multi-GPU-based Smoothed
Particle Hydrodynamics Code and Comparison with Experimental Result,” ICONE-28,
August 2–6, Anaheim, USA, 2020.
§ Jo, Y.B., and Kim, E.S., “Numerical Simulation on LMR
Molten-Core Centralized Sloshing Behaviors with Single/Multi-Phase Smoothed
Particle Hydrodynamics Based on Novel Density Formulation,” NURETH-18, August
18–23, 2019 Portland, Oregon, USA, 2019.
§ Ahn, Y., Jo, Y.B., Park, S.H., Kim, J.W., and Kim, E.S., “SPH
Simulation on Single Bubble Behavior in Linear Shear Flow,” NURETH-18, August
18–23, 2019 Portland, Oregon, USA, 2019.
§ Park et al., “Development of SOPHIA-MARS Integrated Code Based
on Smoothed Particle Hydrodynamics Method and Preliminary Simulation on
In-Vessel Retention and External Reactor Vessel Cooling,” Transactions of the
Korean Nuclear Society Spring Meeting Jeju, Korea, May 21–22, 2020.
§ Chae et al., “Simulation of Jet Break-up in Complicated
Structure in BWR Lower Plenum using Smoothed Particle Hydrodynamics,”
Transactions of the Korean Nuclear Society Spring Meeting Jeju, Korea, May 21–22,
11. CONTENTS OF CODE PACKAGE
The package is transmitted digitally
as a download link in .zip format. It includes reference material,
documentation, source files, and sample problems. Application executables are
included with the package.
12. DATE OF ABSTRACT
KEYWORDS: Lagrange equations, accident analysis, hydrodynamics,
multiphase flow, safety analysis, severe accident, thermal hydraulics.