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CAVEAT

The two-dimensional version of CAVEAT is a computer code which solves numerically the equations of transient, multimaterial, compressible fluid dynamics. CAVEAT is written to treat a wide variety of problems. It has the ability, for example, to describe material interfaces and the large slip along interfaces, to describe complex geometries without sacrificing vector processing, and to apply tabular equations of state (SESAME library). Its numerical methods were chosen to minimize numerical diffusion, achieve a high degree of vectorization, and facilitate extension to three dimensions.

CAVEAT uses an explicit time-marching, conservative finite-volume numerical technique in which all state variables, including velocity, are cell centered; values at vertices and cell faces are derived. The technique is a variation of the Godunov method that uses an approximate Riemann solver and accommodates arbitrary equations of state. Spatial differencing may either be first order (constant across the cell) or second order (linear variation across the cell) with a choice of limiters of the gradient in an attempt to preserve monotonicity. The formulation is spatially two-dimensional with options for Cartesian and curvilinear geometries. Discretization is achieved with a mesh of arbitrary quadrilateral cells whose vertices can move with time. Arbitrary mesh motion is supported by allowing transport of material between cells according to the Arbitrary Lagrangian-Eulerian (ALE) technique. The computation is performed in two phases: a Lagrangian phase and a remapping phase in which conserved variables are transferred from the Lagrangian mesh to an arbitrary specified mesh. The dynamic mesh capability generally smooths distortions in the mesh and can also result in higher resolution around features of interest, such as a shock discontinuity.

A manual for CAVEAT is available (below). Because of the maturity and expanded use of CAVEAT, this manual includes new sections directed toward first-time users. The main improvements and changes to the hydrodynamics since the last release are the addition of interacting blocks of mesh, greatly improved vectorization, directional splitting in the remap phase, a faster global rezone method, and a new tangential rezone method.

Learn more about Caveat through the users Manual (LA-10613-MS-REVISED, pdf, 800k).

For more information about CAVEAT, contact Norman Johnson at nlj@lanl.gov.