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Search Publications by: Nicos Martys (Fed)

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Displaying 76 - 92 of 92

Accelerating Scientific Discovery through Computation and Visualization

November 1, 2000
Author(s)
James S. Sims, John G. Hagedorn, Peter M. Ketcham, Steven G. Satterfield, Terence J. Griffin, William L. George, H A. Fowler, B A. am Ende, Howard Hung, Robert B. Bohn, John E. Koontz, Nicos Martys, Charles E. Bouldin, James A. Warren, D L. Feder, Charles W. Clark, Bernard J. Filla, Judith E. Terrill
The rate of scientific discovery can be accelerated through computation and visualization. This acceleration results from the synergy of expertise, computing tools, and hardware for enabling high performance computation, information science, and

User's Guide to the NIST Virtual Cement and Concrete Testing Laboratory. Version 1.0

November 1, 2000
Author(s)
Jeffrey W. Bullard, Chiara F. Ferraris, Edward J. Garboczi, Nicos Martys, Paul E. Stutzman
This NISTIR serves as the user's manual for Version 1.0 of the Virtual Cement and Concrete Testing Laboratory (VCCTL). Using the VCCTL, a user may create starting microstructures of cement (gypsum, fly ash, etc.) particles in water, hydrate the

Simulation of Fluid Flow and Permeability in Cohesionless Soils

April 1, 2000
Author(s)
E Masad, B Muhunthan, Nicos Martys
This paper reports on a new laboratory methodology for the determination of the structure of pores, a method for the analysis of the data to obtain the statistics of the pore structure distribution, simulation of porous media with statistics consistent

Energy Conserving Discrete Equation for Non-Ideal Systems

October 20, 1999
Author(s)
Nicos Martys
The BBGKY formalism is utilized to obtain a set of moment equations to be satisfied so as to obtain an energy conserving discrete Boltzmann equation for the case of a non-local interaction potential. A modified BGK form of the collision operator consistent

Diffusion in Partially Saturated Porous Materials

October 1, 1999
Author(s)
Nicos Martys
The diffusive transport of ions in two classes of porous media was studied as a function of fluid saturation and wetting properties. A lattice Boltzmann method was used to model phase separation of a binary mixture, including wetting effects, in porous

Energy Conserving Discrete Boltzmann Equation for Nonideal Systems

October 1, 1999
Author(s)
Nicos Martys
The BBGKY formalism is utilized to obtain a set of moment equations to be satisfied by the collision operator in an energy conserving discrete Boltzmann equation for the case of a nonlocal interaction potential. A modified BGK form of the collision

Pore Scale Modeling of Fluid Transport Using Lattice Boltzmann Methods

October 1, 1999
Author(s)
Nicos Martys, John G. Hagedorn, J E. Devaney
The utility of the lattice Boltzmann method for modeling fluid flow in complex geometries like porous materials is examined. After study of some simple test cases, results from large scale simulations of fluid flow through digitized Fontainbleau sandstone

Digital Images and Computer Modelling

July 1, 1999
Author(s)
Edward J. Garboczi, Dale P. Bentz, Nicos Martys
This chapter describes how digital images of porous materials can be analyzed to give information about the structure and properties of the material, describes various ways 3-D digital-image-based models can be generated to help understand real materials.

Large Scale Simulations of Single and Multi-Component Flow in Porous Media

July 1, 1999
Author(s)
Nicos Martys, John G. Hagedorn, D S. Goujon, J E. Devaney
We examine the utility of the lattice Boltzmann method for modeling fluid flow in large microstructures. First, results of permeability calculations are compared to predicted values for several idealized geometries. Large scale simulations of fluid flow

Lattice Boltzmann Simulations of Single and Multi-Component Flow in Porous Media

July 1, 1999
Author(s)
Nicos Martys, John G. Hagedorn, J E. Devaney
We examine the utility of the lattice Boltzmann method for modeling fluid flow in porous media. First the lattice Boltzmann method is validated for the case of single component flow in several idealized flow geometries. Large scale simulations of fluid

Mean-Field-Scaling in Lattice Boltzmann Fluid Mixtures

June 1, 1999
Author(s)
Nicos Martys, Jack F. Douglas
Basic equilibrium properties of Lattice Boltzmann (LB) fluid mixtures (coexistence curve, surface tension, and interfacial profile) are calculated to characterize the critical phenomena occurring in these model liquids and to establish a reduced variable

Thermal Lattice Boltzmann Models (TLBM) for Compressible Flows

December 1, 1998
Author(s)
G Vahala, P Pavlo, L Vahala, Nicos Martys
The progress and challenges in thermal lattice Boltzmann modeling are discussed. In particular, momentum and energy closures schemes are contrasted. Higher order symmetric (but no longer space filling) velocity lattices are constructed for both 2D and 3D

Evaluation of the External Force Term in the Discrete Boltzmann Equation

November 1, 1998
Author(s)
Nicos Martys, X Shan, H Chen
A representation of the forcing term in the Boltzmann equation based on Hermite expansion of the Boltzmann distribution function in velocity phase space is derived. Based on this description of the forcing term, a systematic comparison of previous Lattice