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The KIVA family of Computational Fluid Dynamics (CFD) software predicts complex fuel and air flows as well as ignition, combustion, and pollutant-formation processes in engines. The KIVA models have been used to understand combustion chemistry processes, such as auto-ignition of fuels, and to optimize diesel engines for high efficiency and low emissions.
IVA-3V is the most mature version of KIVA still maintained and distributed through LANL; it is an improved version of the earlier Federal Laboratory Consortium Excellence in Technology Transfer Award-winning KIVA3 (1993), extended to model vertical or canted valves in the cylinder head of a gasoline or diesel engine. KIVA3, in turn, was based on the earlier KIVA2 (1989) and used the same numerical solution procedure and solved the same types of equations.
KIVA-3V uses a block-structured mesh with connectivity defined through indirect addressing. The departure from a single rectangular structure in logical space allows complex geometries to be modeled with significantly greater efficiency because large regions of deactivated cells are no longer necessary. Cell-face boundary conditions permit greater flexibility and simplification in the application of boundary conditions. KIVA-3V also contains a number of significant improvements over its predecessors. New features enhanced the robustness, efficiency, and usefulness of the overall program for engine modeling. Automatic restart of the cycle with a reduced timestep in case of iteration limit or temperature overflow effectively reduced code crashes. A new option provided automatic deactivation of a port region when it is closed from the cylinder and reactivation when it communicates with the cylinder. Extensions to the particle-based liquid wall film model made the model more complete and a split injection option was also added. A new subroutine monitors the liquid and gaseous fuel phases and energy balance data and emissions are monitored and printed. In addition, new features were added to the LANL-developed grid generator, K3PREP, and the KIVA graphics post processor, K3POST.
KIVA-4 is maintained and distributed through LANL. While KIVA-4 maintains the full generality of KIVA-3V, it adds the capability of computing with unstructured grids. Unstructured grids can be generated more easily than structured grids for complex geometries. The unstructured grids may be composed of a variety of elements including hexahedra, prisms, pyramids, and tetrahedra. However, the numerical accuracy diminishes when the grid is not composed of hexahedra.
KIVA-4 was developed to work with the many geometries accommodated within KIVA-3V, which includes 2D axisymmetric, 2D planar, 3D axisymmetric sector geometries, and full 3D geometries. KIVA-4 also features a multicomponent fuel evaporation algorithm. Many of the numerical algorithms in KIVA-3V generalize properly to unstructured meshes; however, fundamental changes were needed in the solution of the pressure equation and the fluxing of momentum. In addition, KIVA-4 loops over cell faces to compute diffusion terms.
Recently, LANL researchers developed KIVA-4mpi, a parallel version of KIVA-4, and the most advanced version of KIVA maintained and distributed by LANL. KIVA-4mpi also solves chemically reacting, turbulent, multi-phase viscous flows, but does this on multiple computer processors with a distributed computational domain (grid). KIVA-4mpi internal combustion engine modeling capabilities are the same as that of KIVA-4, and are based on the KIVA-4 unstructured grid code. The software is well suited for modeling internal combustion engines on multiple processors using the message passing interface (MPI).
On August 9, 2011, LANL honored the authors of KIVA-4mpi with the Distinguished Copyright Award for demonstrating a breadth of commercial applications, potential to create economic value, and the highest level of technical excellence.
KIVA-EXEC is a free, reduced-functionality executable-only trial version of KIVA-4. KIVA-EXEC has all the performance of Los Alamos National Laboratory’s premier KIVA-4 code, but with a 45K cell limitation.
KIVA-EXEC is perfect for beginners who do not need or intend to modify the source code.