Nicos Martys

National Institute of Standards and Technology

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Chiara F. Ferraris

National Institute of Standards and Technology

Edward J. Garboczi

National Institute of Standards and Technology

Dale P. Bentz

National Institute of Standards and Technology

William L. George

National Institute of Standards and Technology

John G. Hagedorn

Information Technology Laboratory

Didier Lootens

Sig Holding (Switzerland)

Jeffrey W. Bullard

Texas A&M University

Paul E. Stutzman

National Institute of Standards and Technology

Scott Z. Jones

National Institute of Standards and Technology

J E. Devaney

National Institute of Standards and Technology

Cooperative Institutions

National Institute of Standards and Technology

109

National Institute of Standards

United States Department of Commerce

Information Technology Laboratory

NIST Center for Neutron Research

Material Measurement Laboratory

Physical Measurement Laboratory

University of Maryland, College Park

Centre National de la Recherche Scientifique

University of Delaware

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Suppression of Capillary Instability of a Polymeric Thread via Parallel Plate Confinement

Macromolecules (2003)

Younggon Son Nicos Martys John G. Hagedorn Kalman B. Migler

We investigate the stability of a polymer thread imbedded in a matrix that is confined between two parallel plates. Utilizing a combination of experiments, numerical simulations (lattice−Boltzmann), and surface area calculations, we find substantial deviations from the classical results when the diameter of the thread (D0) is comparable to the height (H) of the matrix. We find three regimes as a function of H/D0: For H/D0≳ 3, the thread breaks up into droplets through a finite wavelength axisymmetric capillary instability as described by Rayleigh and Tomotika. For 1.3 ≲ H/D0 ≲ 3, the effects of the confinement are felt; the shape becomes nonaxisymmetric, the early-stage growth rate decreases, and the wavelength increases. For sufficiently low H/D0, we observe that the thread is stable with respect to the capillary instability over the experimental time scales. The simulations qualitatively agree with the experiments and reveal that while the shape of the growing bulges is nonaxisymmetic, the narrowing necks are circular. A simple surface area consideration then shows that as the wall-induced asymmetry of the fluctuation increases, the minimally unstable wavelength increases and eventually diverges.

Lattice Boltzmann methods

10.1021/ma0343986

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Citations (55)

Spatial-Temporal Correlations at the Onset of Flow in Concentrated Suspensions

AIP conference proceedings (2008)

Nicos Martys Didier Lootens William L. George Steven G. Satterfield Pascal Hébraud

Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter Facebook Reddit LinkedIn Tools Icon Tools Reprints and Permissions Cite Icon Cite Search Site Citation Nicos S. Martys, Didier Lootens, William L. George, Steven G. Satterfield, Pascal Hébraud; Spatial‐Temporal Correlations at the Onset of Flow in Concentrated Suspensions. AIP Conf. Proc. 7 July 2008; 1027 (1): 207–209. https://doi.org/10.1063/1.2964636 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAIP Publishing PortfolioAIP Conference Proceedings Search Advanced Search |Citation Search

10.1063/1.2964636

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Critical phenomena in fluid invasion of porous media

Physical Review Letters (1991)

Nicos Martys Marek Cieplak Mark O. Robbins

We present a phase diagram for fluid invasion of porous media as a function of pressure P and the contact angle \ensuremath{\theta} of the invading fluid. Increasing P leads to perculation above a critical ${\mathrm{\ensuremath{\theta}}}_{\mathit{c}}$, and depinning below ${\mathrm{\ensuremath{\theta}}}_{\mathit{c}}$. Depinning is characterized by a diverging coherence length and the power-law distribution of events typical of self-organized critical phenomena. At the transition from percolation to depinning another correlation length diverges and an order parameter, an effective macroscopic surface tension, becomes nonzero. The fluid interface changes from self-similar to self-affine. Results are compared to experiments.

Percolation (cognitive psychology)

10.1103/physrevlett.66.1058

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Citations (192)

Using impedance spectroscopy to assess the viability of the rapid chloride test for determining concrete conductivity

Journal of Research of the National Institute of Standards and Technology (2000)

Kenneth A. Snyder Chiara F. Ferraris Nicos Martys Edward J. Garboczi

The suitability of using the initial current from the rapid chloride test (ASTM C 1202) to determine specimen conductivity is tested using impedance spectroscopy with a frequency spectrum of 10 Hz to 1 MHz. The specimen conductivity has an analytical relationship to specimen diffusivity and so is a useful quantity in service life prediction. Measurements made on specimens of different lengths indicate that the total charge passed during the six hour conduction test carried out according to ASTM C 1202 is not a direct measure of specimen conductivity. Further, ohmic heating during the 6 hour test makes it nearly impossible to directly measure any specimen transport property from the results. The total charge passed during the 6 hour conduction test is, therefore, not a reliable quantity for service life prediction. Results indicate that the direct current (dc) measurement of resistance using a voltage of 60 V is sufficient to overwhelm polarization effects, thereby yielding an accurate estimate of the true specimen conductivity. Impedance spectroscopy measurements also indicate that corrosion may form on the brass electrodes, adding bias to a conductivity estimate based upon a dc measurement.

10.6028/jres.105.040

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Citations (87)

Report of Phase One Measurement and Analysis of Building Water System Contamination and Decontamination | NIST

Stephen J. Treado Mark A. Kedzierski Stephanie S. Watson Dale P. Bentz Nicos Martys

NIST

Human decontamination

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Simulation of Droplet Breakup Using a Lattice Boltzmann Method

Frederick R. Phelan Nicos Martys

Lattice Boltzmann methods

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Citations (1)

Pore Scale Modeling of Fluid Transport Using Lattice Boltzmann Methods | NIST

Nicos Martys John G. Hagedorn J E. Devaney

NIST

Lattice Boltzmann methods

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Thermal Lattice-Boltzmann Models (TLBM) for Compressible Flows

International Journal of Modern Physics C (1998)

George Vahala P. Pavlo Linda 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 flows and shown to have superior stability properties to the standard (but lower) symmetry lattices. While this decouples the velocity lattice from the spatial grid, the interpolation required following free-streaming is just 1D. The connection between fixed lattice vectors and temperature-dependent lattice vectors (obtained in the Gauss–Hermite quadrature approach) is discussed. Some (compressible) Rayleigh–Benard simulations on the 2D octagonal lattice are presented for extended BGK collision operators that allow for arbitrary Prandtl numbers.

Lattice Boltzmann methods

Bhatnagar–Gross–Krook operator

Lattice (music)

Flux limiter

10.1142/s0129183198001126

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Citations (44)

Cement and Concrete Materials Research at the National Institute of Standards and Technology (NIST) | NIST

Edward J. Garboczi Dale P. Bentz Jeffrey W. Bullard Chiara F. Ferraris Nicos Martys

NIST

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