1 / 17

Water Packer Nearly-Implicit Scheme

Water Packer Nearly-Implicit Scheme. Rich Riemke. 2010 RELAP5 International Users Seminar September 20-23, 2010 West Yellowstone, Montana . Introduction.

mali
Download Presentation

Water Packer Nearly-Implicit Scheme

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Water Packer Nearly-Implicit Scheme Rich Riemke 2010 RELAP5 International Users Seminar September 20-23, 2010 West Yellowstone, Montana

  2. Introduction • RELAP5-3D currently has a water packing mitigation scheme (water packer) for the semi-implicit scheme but does not have a water packing mitigation scheme for the nearly-implicit scheme. • Purpose of this task was to add a water packing mitigation scheme to the code for the nearly-implicit scheme, to carry out a full debug/verification, and to document this in a letter report and in the code manuals.

  3. Subtasks • Necessary coding changes were made to add water packer for nearly-implicit scheme. • Verification consisted of 2 vertical fill problems (original problem used for the semi-implicit scheme and modified problem that requests a time step that violates the material Courant limit), manometer problem, current installation problems (script), and developmental assessment problems (script). • Letter report was written, manuals were changed, and updates were submitted for inclusion in the code.

  4. Coding Changes • Subroutines VIMPLT, PIMPLT, and HYDRO were modified to add water packing mitigation scheme for nearly-implicit scheme. • Detection logic to determine if water packing occurs is in subroutines PACKER (semi-implicit) and PIMPLT (nearly-implicit). • Value of variable FACTOR is different between semi-implicit scheme and nearly-implicit scheme. • Variable FACTOR is used in liquid momentum equation for semi-implicit scheme; used in sum and difference momentum equations for nearly-implicit scheme.

  5. Coding Changes (continued) • The 0.01 m/s change used in semi-implicit scheme is not used in nearly-implicit scheme. • Cleaned up coding in subroutines PACKER,VIMPLT, and VFINL (coding alignment and consistent coding style).

  6. Verification • Original vertical fill problem (maximum requested time step 0.05 s). • Subcooled water injected from below into vertical pipe initially filled with superheated steam. • Input flags: level model off, vertical stratification on, wall friction on. • Plots points obtained every time step.

  7. Verification (continued) • Semi-implicit scheme, no water packer.

  8. Verification (continued) • Semi-implicit scheme, water packer (spike at 8.1 s did not appear in RELAP5-MOD2; under investigation).

  9. Verification (continued) • Nearly-implicit scheme, no water packer.

  10. Verification (continued) • Nearly-implicit scheme, water packer.

  11. Verification (continue) • Modified vertical fill problem (maximum requested time step 1.0 s, violates material Courant limit). • Subcooled water injected from below into vertical pipe initially filled with superheated steam. • Input flags: level model off, vertical stratification on, wall friction on. • Plots points obtained every time step.

  12. Verification (continue) • Nearly-implicit scheme, no water packer.

  13. Verification (continue) • Nearly-implicit scheme, water packer (spike at 2.8 s under investigation).

  14. Verification (continue) • Manometer problem. • Consists of 20 volume pipe – 10 volumes oriented vertically down, 10 volumes oriented vertically up. • Bottom 5 volumes on each side filled with water. • Initial velocity -1.0 m/s at each junction; symmetry calculation with 1.0 m/s at each junction. • Input flags: level model on, packer on, vertical stratification off, wall friction off; problem used in developmental assessment (DA). • Water packer does not come on (level model handles junction crossing); results same as version 2.9.2 DA.

  15. Verification (continue) • Current installation problems (script). • Installation problems that use nearly-implicit scheme are identical to those without code modifications. • This is to be expected since these problems are such that water packing should not occur.

  16. Verification (continue) • Developmental assessment (DA) problems (script). • All run successfully except for LOFT L2-5 nearly-implicit scheme, which fails with and without the update with a thermodynamic property failure at the minimum time step. • ‘Diffem’ script shows some differences in some nearly-implicit DA problems (LOFT L2-5, water over steam, ROSA-IV SB-CL-18, Semiscale NC 1, 2, 3, 10; these were expected).

  17. Summary • Purpose of this task was to add a water packing mitigation scheme to the code for the nearly-implicit scheme, to carry out a full debug/verification, and to document this in a letter report and in the code manuals; this was completed. • Original fill semi-implicit scheme spike at 8.1 s and modified fill nearly-implicit scheme spike at 2.8 s are under investigation.

More Related