Modeling and Simulation of Physical, Chemical, and Mechanical Systems

Material Structure and Spectroscopy

• DIATOM Spectral Simulation Computer Program, Version 7.0 (1994) is a spectroscopy modeling code, developed at SRI, for simulation of emission and absorption spectra of diatomic molecules.

• BIOSYM: SRI has access to the entire suite of Biosym Technologies, Inc. codes which provide state-of-the-art molecular modeling and quantum chemistry applications for prediction of properties of chemicals, materials, polymers, and for drug design.

• Solid-State Codes: SRI is developing industry-leading electronic structure codes based on the local density exchange approximation. Our new algorithms lead to computational efficiency that enables accurate large-scale calculations of the interactions of molecules with surfaces.

Electromagnetic, Plasma, and Particle Physics

• PDP1, PDS1, and PDC1 Plasma Simulation Codes: These codes were developed in the EECS Department at the University of California at Berkeley and at Lawrence Livermore National Laboratory. They are useful for simulating electrostatic phenomena in plasmas and are currently being used to study rf discharges and other materials processing plasmas. They can handle a variety of planar (PDP1), spherical (PDS1) and cylindrical (PDC1) boundary conditions and are based on particle-in-cell methods. They compute particle displacements in one dimension, and allow three velocity components.

• Langmuir Probe Data Analysis Packages: These programs analyze the characteristic current-voltage (IV) curves obtained from Langmuir probes so that plasma parameters such as plasma potential, electron and ion density, and electron temperatures may be obtained. Depending on particular circumstances, probe theories used include Laframboise analysis, simple ion flux models, or orbital-limited motion models.

• Electromagnetics Code: One illustrative code developed by SRI is called BMAP, which calculated radar cross sections for rocket exhaust plumes, with complex chemical composition, and nonhomogeneous gas flows.

Optical Physics

• Blackbody Radiation Code: This code predicts the spectral emission of blackbodies with arbitrary spectral emissivities and temperatures.

• Beam-Four(TM) Optical Ray-Tracing Code: created by Stellar Software, Inc. was purchased by SRI to facilitate the design and layouts of optical systems. It is a geometrical ray tracing code and can handle optical materials with arbitrary optical constants.

Chemical Kinetics

• OLCHEM Chemical-Rate-Equation Integrator is a small, easy-to-use chemical kinetics code for simulation of time evolution of chemical species densities for spatially uniform or zero-dimensional boundary conditions at fixed temperature. OLCHEM is especially convenient for exploration and building and validation of both detailed mechanistic models and lumped kinetic models. OLCHEM is based on computer codes written in the late 1970s at Science Applications International Corporation (SAIC) and the Lawrence Livermore National Laboratory (LLNL).

• Chemkin/Premix: CHEMKIN is a package written at Sandia National Laboratory (Livermore) for consistent thermodynamic treatment of reversible chemical reactions. When combined with an equation-solver package (from LLNL) and a main program describing the chemical reaction system (written by the user), it is capable of investigating quite complicated systems, including fluid dynamics and diffusion in one spatial dimension, and heat evolution. SRI has developed the PREMIX computer code based on these components and used it to model problems such as the spatial and temporal distribution of intermediates in a variety of hydrocarbon flames.

• Spin: A gas-surface chemistry modeling code (so named because CVD substrates are often spun during manufacturing). Developed at Sandia Livermore to model chemical vapor deposition reactor with cylindrical symmetric geometry. This includes gas phase chemistry as well as gas-surfaces interactions.

• Senkin: A version of the Chemkin code from Sandia Livermore incorporating sensitivity analysis. With this package one may compute first order sensitivities of some given output variable to each input parameter, allowing one to examine the processes that control a particular concentration. The approach may also be used in an inverse manner to discern the sensitivity of unknown code parameters to measured observables. SRI has used this extensively in combustion modeling and is now applying it to modeling of stratospheric ozone depletion. We are the first group to apply sensitivity analysis to chemical kinetics outside the combustion field. A new version, called Surface-Senkin, can treat heterogeneous reactions.

• NLewis: is a thermodynamic code developed at NASA Lewis Research Center. SRI has modified it for use in modeling the burning of solid fuel propellants in rocket engines.

• Fluent CFD Chemistry Code: from Fluent Inc. provides CAD-level geometry modeling of real low-symmetry reactors, sophisticated finite-element computational fluid dynamics, and spatially-resolved chemical reactions, flow fields, and thermal transport.

Atmospheric and Space Science Modeling

• Chapman Function for Atmospheric Attenuation: The Chapman Function, Ch(X,chi0), represents the column depth of an exponential atmosphere integrated along a line from a given point to the sun, divided by the column depth for a vertical sun.

• Jacchia 1977 Atmospheric Model: The Jacchia 1977 thermospheric model is combined with the U.S. Standard Atmosphere 1976 model. Temperature and component number densities are calculated from the ground to the maximum altitude requested.

Engineering Design and Mechanical Modeling

• Finite Element Mechanical Dynamics Codes: SRI is a leader in numerical simulation of stress, wave propagtion, shocks, explosions, deformation, and structural response. The codes SRI-NIKE2D and SRI-DYNAD3D are advanced versions of the general finite-element codes developed at LLNL that are used for wave propagation and structural analysis. The codes SRI-PUFF and S2D simulate shocks and explosive effects.

• CAD/CAE Codes: I-DEAS Master Series software from System Dynamics Research Corporation provides capabilities for solid modeling, finite element analysis, thermal analysis, and dynamic simulation and drafting.

Point of Contact

• David L. Huestis, E-mail: <david.huestis@sri.com>

Related Web Pages

• Atmospheric Chemistry and Space Physics
• Combustion and Flames
• Discharges and Plasmas
• Electronic and Atomic Collisions

• SRI International Home Page

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