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Implementation of the Turn Function Method in KIVA-F90

Technical Report ·
DOI:https://doi.org/10.2172/10176592· OSTI ID:10176592
We document the implementation of the Turn Function Method (TFM) in KIVA-F90, a version of the KIVA computer program written in the FORTRAN 90 programming language that is used on some massively parallel computers. TFM solves both linear momentum and vorticity equations in numerical calculations of compressible fluid flow. Solving a vorticity equation allows vorticity to be both conserved and transported more accurately than is possible in traditional methods for computing compressible flow. To calculate the convective transport of vorticity more accurately, we have also implemented an improved method for the rezone phase of the KIVA computational cycle. This first implementation of TFM in a three-dimensional hydrodynamics code involved some modification of the original method and some novel numerical difference approximations. In particular, we used a penalty method to keep the divergence of the computed vorticity field close to zero. Also, difference operators are defined in such a way that the finite difference analog of {triangledown} {center_dot} ({triangledown} {times} u) = 0 is exactly satisfied. Three example problems presented in this report show the greater accuracy that can be gained when TFM is used for calculations of flows with rotational motion, as well as the added computational costs incurred. Use of the method can increase by 60% the computational times of the Euler equation solver in KIVA-F90. Although TFM sometimes does degrade accuracy in calculations that have large vorticity gradients, generally the calculations show beneficial effects of TFM on accuracy. We will continue to evaluate the costs and benefits of TFM in future KIVA-F90 calculations.
Research Organization:
Los Alamos National Lab., NM (United States)
Sponsoring Organization:
USDOE, Washington, DC (United States)
DOE Contract Number:
W-7405-ENG-36
OSTI ID:
10176592
Report Number(s):
LA--12536-MS; ON: DE93018394
Country of Publication:
United States
Language:
English