An experimenter's perspective on validating codes and models with experiments having shock-accelerated fluid interfaces

In describing several science experiments used to validate applications of codes at Los Alamos National Laboratory, we offer an experimenter's perspective on this process within the context of the US Stockpile Stewardship Program. The validation experiments we describe validate particular models and algorithms that may be used in weapons codes. Code validation at Los Alamos National Laboratory has changed with the cessation of underground nuclear weapons testing (UGT). The US is now committed to stewardship of the nuclear weapons stockpile without full-scale testing, so small-scale experiments validate code modules that are candidate improvements to weapons codes. An essential module of a weapons code is fluid dynamics. This article discusses several experiments designed to validate the capability of a fluid simulation code - called a hydrocode - to calculate the complex flow of a fluid interface accelerated by a shock wave.