Research
Research

Publications

Results 88151–88200 of 100,993

Search results

Jump to search filters

Progress report for the ASCI AD resistance weld process modeling project AD2003-15

Winters, William S.; Brown, Arthur; Bammann, Douglas J.; Foulk, James W.; Ortega, Arthur R.

This report documents activities related to the ASCI AD Resistance Weld Process Modeling Project AD2003-15. Activities up to and including FY2004 are discussed. This was the third year for this multi year project, the objective of which is to position the SIERRA computational tools for the solution of resistance welding problems. The process of interest is a three-way coupled problem involving current flow, temperature buildup and large plastic deformation. The DSW application is the reclamation stem weld used in the manufacture of high pressure gas bottles. This is the first year the CALAGIO suite of codes (eCALORE, CALORE, and ADAGIO) was used to successfully solve a three-way coupled problem in SIERRA. This report discusses the application of CALAGIO to the tapered bar acceptance problem and a similar but independent tapered bar simulation of a companion C6 experiment. New additions to the EMMI constitutive model and issues related to CALAGIO performance are also discussed.

More Details
TYPE SAND Report YEAR 2005
DOIOSTI

Density functional theory and molecular dynamics simulation of poly(dimethylsiloxane) melts near silica surfaces

Proposed for publication in Macromolecules.

Curro, John G.; Frischknecht, Amalie L.

Classical density functional theory (DFT) is applied to study properties of fully detailed, realistic models of poly(dimethylsiloxane) liquids near silica surfaces and compared to results from molecular dynamics simulations. In solving the DFT equations, the direct correlation functions are obtained from the polymer reference interaction site model (PRISM) theory for the repulsive parts of the interatomic interactions, and the attractions are treated via the random-phase approximation (RPA). Good agreement between density profiles calculated from DFT and from the simulations is obtained with empirical scaling of the direct correlation functions. Separate scaling factors are required for the PRISM and RPA parts of the direct correlation functions. Theoretical predictions of stress profiles, normal pressure, and surface tensions are also in reasonable agreement with simulation results.

More Details
TYPE Journal Article YEAR 2005
OSTI

Large-scale stabilized FE computational analysis of nonlinear steady state transport/reaction systems

Proposed for publication in Computer Methods in Applied Mechanics and Engineering.

Shadid, John N.; Salinger, Andrew G.; Pawlowski, Roger; Lin, Paul T.; Hennigan, Gary L.; Tuminaro, Raymond S.; Lehoucq, Richard B.

The solution of the governing steady transport equations for momentum, heat and mass transfer in fluids undergoing non-equilibrium chemical reactions can be extremely challenging. The difficulties arise from both the complexity of the nonlinear solution behavior as well as the nonlinear, coupled, non-symmetric nature of the system of algebraic equations that results from spatial discretization of the PDEs. In this paper, we briefly review progress on developing a stabilized finite element (FE) capability for numerical solution of these challenging problems. The discussion considers the stabilized FE formulation for the low Mach number Navier-Stokes equations with heat and mass transport with non-equilibrium chemical reactions, and the solution methods necessary for detailed analysis of these complex systems. The solution algorithms include robust nonlinear and linear solution schemes, parameter continuation methods, and linear stability analysis techniques. Our discussion considers computational efficiency, scalability, and some implementation issues of the solution methods. Computational results are presented for a CFD benchmark problem as well as for a number of large-scale, 2D and 3D, engineering transport/reaction applications.

More Details
TYPE Journal Article YEAR 2005
OSTI
Results 88151–88200 of 100,993
Results 88151–88200 of 100,993
Top