Publications

Progress Towards A New CTH Code Verification & Validation Test Suite

Duncan-Reynolds, Gabrielle C.; Key, Christopher T.

The CTH multiphysics hydrocode is used in a wide variety of important calculations. An essential part of ensuring hydrocode accuracy and credibility is thorough code verification and validation (V&V). In the past, CTH V&V work (particularly verification) has not been consistently well documented. In FY19, we have made substantial progress towards addressing this need. In this report, we present a new CTH V&V test suite composed of traditional hydrocode verification problems used by similar ASC codes as well as validation problems for some of the most frequently used materials models and capabilities in CTH. For the verification problems, we present not only results and computed errors, but also convergence rates. Validation problems include mesh refinement studies, providing evidence that results are converging. CTH performs well overall on the new V&V test suite, though the test suite itself still only covers a fraction of CTH capabilities. Accuracy and convergence rates for traditional verification problems such as Sedov, Noh, and the 1D Riemann problems are comparable to similar ASC codes. Likewise, CTH simulation results show good agreement with experimental validation data for the AVAVE, EPPVM, and Johnson-Cook strength models as well as for the Mie-Griineisen EOS for the materials tested. Future V&V work will add testing for other frequently used material models and code capabilities, helping to provide confidence in simulation results for critical analyses. ACKNOWLEDGEMENTS The authors would like to thank Brian Carnes, Jim Cox, and Kevin Dowding for helpful discussions. We would also like to acknowledge the valuable resources published by Los Alamos National Laboratory, such as the code verification tool ExactPack 1 , which was used in this work to calculate and plot analytic solutions, and the Standardized Definitions for Code Verification Problems 2 , which was helpful in implementing the ASC Tri-Lab Test Suite problems. Finally, we wish to thank Kim Mish, Angel Urbina, and Walter Witkowski for supporting this work. 1 R. Singleton Jr, D. M. Israel, S. W. Doebling, C. N. Woods, A. Kaul, J. W. Walter Jr, and M. L. Rogers, Exactpack documentation, tech. rep., Los Alamos National Lab. (LANL), Los Alamos, NM (United States), 2016. 2 J. Kamm, S Doebling, D. Israel, and R. Singleton, Standardized definitions for code verification test problems, tech. rep., LA-UR-14-20418 (Rev. 2), 2014.