Implementation of a pressure correction term in the CTF subchannel code
Abstract
CTF [1] is a modernized and improved version of the legacy subchannel code, COBRATF [2], that is being jointly developed and maintained by Oak Ridge National Laboratory (ORNL) and North Carolina State University. The code was adopted by ORNL for use in the Consortium for Advanced Simulation of Light Water Reactors (CASL) in 2012 for aiding in addressing CASL challenge problems. Since that time, activities related to CTF have included implementing software quality assurance measures, implementing new features and models, performing validation and verification testing, establishing and supporting a CTF User Group, and developing the code for use in coupled applications [3, 4, 5]. CTF is applicable to single and twophase flows in light water reactor geometries at normal and accident operating conditions. The twophase flow model consists of the sixequation twophase flow model [6] augmented by equations for the droplet field and also includes appropriate source terms. This work focuses on the numerical stability of the sixequation twophase flow model and is part of a recent eort to improve CTF capabilities for simulating flows in boiling nuclear reactors (BWRs). As it is of common knowledge among the thermodynamic community, the sixequation twophase flow model is not strongly hyperbolic, meaningmore »
 Authors:

 ORNL
 Sandia National Laboratories (SNL)
 Publication Date:
 Research Org.:
 Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
 Sponsoring Org.:
 USDOE
 OSTI Identifier:
 1427698
 DOE Contract Number:
 AC0500OR22725
 Resource Type:
 Conference
 Resource Relation:
 Conference: 2017 ANS Annual Meeting  San Franciso, California, United States of America  6/11/2017 4:00:00 AM6/15/2017 4:00:00 AM
 Country of Publication:
 United States
 Language:
 English
Citation Formats
Delchini, MarcOlivier G., Salko, Robert K., and Mousseau, Vincent A. Implementation of a pressure correction term in the CTF subchannel code. United States: N. p., 2017.
Web.
Delchini, MarcOlivier G., Salko, Robert K., & Mousseau, Vincent A. Implementation of a pressure correction term in the CTF subchannel code. United States.
Delchini, MarcOlivier G., Salko, Robert K., and Mousseau, Vincent A. Thu .
"Implementation of a pressure correction term in the CTF subchannel code". United States. https://www.osti.gov/servlets/purl/1427698.
@article{osti_1427698,
title = {Implementation of a pressure correction term in the CTF subchannel code},
author = {Delchini, MarcOlivier G. and Salko, Robert K. and Mousseau, Vincent A.},
abstractNote = {CTF [1] is a modernized and improved version of the legacy subchannel code, COBRATF [2], that is being jointly developed and maintained by Oak Ridge National Laboratory (ORNL) and North Carolina State University. The code was adopted by ORNL for use in the Consortium for Advanced Simulation of Light Water Reactors (CASL) in 2012 for aiding in addressing CASL challenge problems. Since that time, activities related to CTF have included implementing software quality assurance measures, implementing new features and models, performing validation and verification testing, establishing and supporting a CTF User Group, and developing the code for use in coupled applications [3, 4, 5]. CTF is applicable to single and twophase flows in light water reactor geometries at normal and accident operating conditions. The twophase flow model consists of the sixequation twophase flow model [6] augmented by equations for the droplet field and also includes appropriate source terms. This work focuses on the numerical stability of the sixequation twophase flow model and is part of a recent eort to improve CTF capabilities for simulating flows in boiling nuclear reactors (BWRs). As it is of common knowledge among the thermodynamic community, the sixequation twophase flow model is not strongly hyperbolic, meaning some of its eigenvalues are either not real or not distinct [7]. In a Cauchy sense and for an initialvalue problem, strong hyperbolicity was found to be equivalent to wellposedness which ensures uniqueness of the solution in the spacetime used. This concept is also of importance when designing highorder numerical methods and also when implementing boundary conditions that rely on real eigenvalues such as Riemann solvers. A tremendous amount of research is available in the literature on how to hyperbolize the sixequation twophase flow model by adding ad hoc terms to the system of equations often referred to as virtual mass or interfacial pressure correction term. From a mathematical prospective, the main idea driving this approach is to add terms to the phasic momentum equation containing firstorder partial derivatives of the unknowns to modify the Jacobian matrix and thus canceling the imaginary part of the eigenvalues.For this work it was chosen to implement a interfacial pressure correction (IPC) term on the same model as what was done for the CATHARE system code [8], that allows to recover a twopressure formulation. In the following, the sixequation twophase flow model is recalled along with the IPC term and its influence on the eigenvalues. Then, numerical results and convergence studies are presented for a waterfaucet problem [9] at a pressure of 10 bar. Finally, conclusions and future work are addressed.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {2017},
month = {6}
}