Showing papers on "Mixture theory published in 1995"
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01 Oct 1995
TL;DR: In this article, a discussion of a mixture of immiscible fluids is given, and the status of Darcy's law within the context of mixture theory is discussed. And the entropy inequality constitutive theory steady state problems diffusing singular surface wave propagation in solids infused with fluids are discussed.
Abstract: Kinematics partial stress and total stress balance laws and the entropy inequality constitutive theory steady state problems diffusing singular surface wave propagation in solids infused with fluids epilogue some results from differential geometry status of Darcy's law within the context of mixture theory a brief discussion of a mixture of immiscible fluids.
614 citations
TL;DR: In this paper, the Muller-Liu approach is extended to the formulation and exploitation of the mixture entropy inequality for a saturated or unsaturated, single-temperature mixture of n (⩾2) heat-conducting, isotropic viscous materials, the first m ⩽ n of which possess a variable true mass density.
115 citations
TL;DR: In this paper, a multicontinuum theory designed specifically for the analysis of composite material systems is presented, which is used to predict the yield surface of a unidirectional boron/aluminum composite in the course of an analysis carried out at the structural level.
19 citations
26 Jul 1995
TL;DR: In this article, a general methodology for design and analysis of mixture optimisation experiments is developed, focusing on multivariate investigation of the zone of optimal solution properties as a function of the ion composition and the total ionic concentration of the solution.
Abstract: This study demonstrates that nutrient solutions can be defined as 'mixture systems'. A general methodology for design and analysis of mixture optimisation experiments is developed. The emphasis is centred on multivariate investigation of the zone of optimal solution properties as a function of the ion composition and the total ionic concentration of the solution. The study of the effects of ion interaction on well defined solution properties is also possible by this multivariate approach. This work is a valuable tool in mineral nutritional research, because for the first time the chemical feasibility conditions of such solution, combined with additional chemical, physiological or economical constraints, form the foundation of the statistical experimental design theory, which makes the optimisation of complex mixtures of ions in relation to well-defined response variables possible.
17 citations
TL;DR: In this paper, a principle of similarity applicable to saturated sands under the so-called one gravity (1-g) model testing, as opposed to centrifugal testing say, is developed.
6 citations
TL;DR: In this paper, the deformation gradient associated with the motion of any constituent can be decomposed into a constitutively prescribed, or deformation, component and another component referred to as the carrier component.
5 citations
TL;DR: In this article, a Courant violating scheme is examined for the mixture drift-flux equations, which for rapid transients is at least as fast as classic semi-implicit methods and for slow transients allows time step sizes many times greater than the material Courant limit.
Abstract: Mixture models are commonly used in the simulation of transient two-phase flows as simplifications of six-equation models, with the drift-flux models as a common way to describe relative phase motion. This is particularly true in simulator and control system modeling where solutions that are faster than real time are necessary, and as a means for incorporating thermal-hydraulic feedback into steady-state and transient neutronics calculations. Variations on semi-implicit finite difference schemes are some of the more commonly used temporal discretization schemes. The maximum time step size associated with these schemes is normally assumed to be limited by stability considerations to the material transport time across any computational cell (Courant limit). In applications requiring solutions that are faster than real time or the calculation of thermal-hydraulic feedback in reactor kinetics codes, time-step sizes that are restricted by the material Courant limit may result in prohibitive run times. A Courant violating scheme is examined for the mixture drift-flux equations, which for rapid transients is at least as fast as classic semi-implicit methods and for slow transients allows time step sizes many times greater than the material Courant limit.
4 citations
TL;DR: In this paper, the authors describe a procedure in which simplified constitutive models for random composites can be defined from the mechanical behavior of each component, which does not rely on a linear elastic analysis of the microstructure.
3 citations
31 Mar 1995
TL;DR: In this article, a 2D laser surface remelting problem is numerically simulated using a multiphase model, constructed from classical mixture theory, and numerical results show the modifications caused by an increase of the free surface shear stress (represented by the Reynolds number Re) upon the stability of thermocapillary flow in the melting pool.
Abstract: A 2D laser surface remelting problem is numerically simulated. The mathematical formulation of this multiphase problem is obtained using a continuum model, constructed from classical mixture theory. This formulation permits to construct a set of continuum conservation equations for pure or binary, solid-liquid phase change systems. The numerical resolution of this set of coupled partial differential equations is performed using a finite volume method associated with a PISO algorithm. The numerical results show the modifications caused by an increase of the free surface shear stress (represented by the Reynolds number Re) upon the stability of the thermocapillary flow in the melting pool. The solutions exhibit a symmetry-- breaking flow transition, oscillatory behavior at higher values of Re. The spectral analysis of temperature and velocity signals for particular points situated in the melted pool, show that these oscillations are at first mono-periodic then new frequencies appear generating a quasi- periodic behavior. These oscillations of the flow in the melted pool could induced the deformation of the free surface which could explain the formation of surface ripples observed during laser surface treatments (surface remelting, cladding) or laser welding.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.
1 citations
31 Dec 1995
TL;DR: In this article, a nonequilibrium mixture theory has been developed and incorporated into the shock physics code, CTH, to model the shock-induced behavior of porous or damaged energetic materials.
Abstract: To model the shock-induced behavior of porous or damaged energetic materials, a nonequilibrium mixture theory has been developed and incorporated into the shock physics code, CTH. Foundation for this multiphase model is based on a continuum mixture formulation given by Baer and Nunziato. In this nonequilibrium approach, multiple thermodynamic and mechanics fields are resolved including the effects of material relative motion, rate-dependent compaction, drag and heat transfer interphase effects and multiple-step combustion. Benchmark calculations are presented which simulate low-velocity piston impact on a propellant porous bed and experimentally-measured wave features are well replicated with this model. This mixture model introduces micromechanical models for the initiation and growth of reactive multicomponent flow which are key features to describe shock initiation and self-accelerated deflagration-to-detonation combustion behavior. To complement one-dimensional simulation, two dimensional numerical simulations are presented which indicate wave curvature effects due to the loss of wall confinement.