Comparison Between a Von Neumann-Richtmyer Hydrocode (AFWL's PUFF) and a Lax-Wendroff Hydrocode
Technical rept. Aug 1967-Aug 1968
AIR FORCE WEAPONS LAB KIRTLAND AFB NM
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A comparison between two one-dimensional Lagrangian hydrocodes has been made. The two hydrocodes are a von Neumann-Richtmyer hydrocode AFWLs PUFF and a Lax-Wendroff hydrocode the two-step version with artificial viscosity. The comparison was made by applying the hydrocode test problems as described in HYDROCODE TEST PROBLEMS, AFWL-TR-67-127, February 1968. The most apparent difference between the von Neumann-Richtmyer hydrocode and the Lax- Wendroff is the greater tendency of the Lax-Wendroff scheme to oscillate. In those flows in which there are no strong shocks or strong rarefactions or vacuums, the Lax-Wendroff scheme is more accurate. However, in those flows in which there are strong shocks or strong rarefactions or vacuums the von Neumann- Richtmyer scheme is more accurate. The Lax-Wendroff scheme cannot handle vacuums because of the use of specific volume instead of the density as a fluid variable. It appears that it might be possible to combine the better features of the von Neumann-Richtmyer and the Lax-Wendroff schemes to produce a better hydrocode.
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