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You searched on: Author: nicos martys

Displaying records 41 to 50 of 77 records.
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41. Breakup of a Fluid Thread in a Confined Geometry: Droplet-Plug Transition Perturbation Sensitivity and Kinetic Stabilization With Confinement .
Published: 5/1/2004
Authors: John G Hagedorn, Nicos Martys, J. F. Douglas
Abstract: We investigate the influence of geometrical confinement on the breakup of long fluid threads in the absence of imposed flow using a lattice Boltzmann model. Our simulations primarily focus on the case of threads centered coaxially in a tube filled wi ...

42. The Rheology of Cementitious Materials: Chemistry, Colloids and Rocks
Published: 5/1/2004
Authors: Robert J Flatt, Nicos Martys
Abstract: Knowledge of colloidal science has proven essential in the development of a new generation of dispersants for concrete. These polymer molecules induce steric repulsion between cement particles, reducing agglomeration and allow high workability to b ...

43. Simulation of Sheared Suspensions With a Parallel Implementation of Quaternion-Based Dissipative Particle Dynamics (QDPD)
Series: Journal of Research (NIST JRES)
Published: 4/1/2004
Authors: James S Sims, Nicos Martys
Abstract: A quaternion-based dissipative particle dynamics (QDPD) program was developed to study the flow properties of complex fluids like suspensions, subject to shear. To overcome CPU speeds limiting the size and complexity of the simulations that can be ca ...

44. Breakup of a Fluid Thread in a Confined Geometry: Droplet-Plug Transition, Perturbation Sensitivity and Kinetic Stabilization with Confinement
Published: 1/1/2004
Authors: John G Hagedorn, Nicos Martys, Jack F Douglas

45. Suppression of Capillary Instability of a Polymeric Thread Via Parallel Plate Confinement
Published: 7/1/2003
Authors: Y Son, Nicos Martys, John G Hagedorn, Kalman D Migler
Abstract: 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 d ...

46. Relating Fresh Concrete Viscosity Measurements From Different Rheometers
Series: Journal of Research (NIST JRES)
Published: 5/1/2003
Authors: Chiara F Ferraris, Nicos Martys
Abstract: The rheological properties of concrete need to be measured and predicted to enable the characterization of special concrete such as self-consolidating concrete (SCC). It was also shown by a round-robin held in 2000 [ , ] that different rheometers g ...

47. Simulation of Droplet Breakup Using a Lattice Boltzmann Method
Published: 5/1/2003
Authors: Frederick R Phelan Jr, Nicos Martys
Abstract: Droplet breakup in homogeneous shear flow at super critical Capillary numbers and a viscosity ratio of unity is studied using a lattice Boltzmann method. We find that the total number of child drops that form from an isolated super critical drop scal ...

48. Multiscaling Modeling of Fluid Transport in Heterogeneous Materials Using Discrete Boltzmann Methods
Published: 12/1/2002
Authors: Nicos Martys, John G Hagedorn
Abstract: The lattice Boltzmann method is a promising approach for modeling single and multicomponent fluid flow in complex geometries like porous materials. Here, we review some of our previous work and discuss some recent developments concerning fluid flow ...

49. Simulation of SCC Flow
Published: 11/1/2002
Authors: Nicos Martys, Chiara F Ferraris
Abstract: Predicting the rheological properties of concrete is essential for its optimal use in situations such as flow between rebars. The aggregate gradation and shape, as well as the rheological properties of the mortar or cement paste will affect the flow ...

50. Research and Challenges of Multi-Scale Mechanics and Modeling
Published: 10/1/2002
Authors: K P Chong, Nicos Martys
Abstract: One of the great challenges in the material sciences is to predict long term performance of materials and structures. Recent efforts have focused on linking nano/micro scalebehavior to meso-scale and macroscale behavior through computational modeli ...

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