A large eddy simulation (LES) code of the atmospheric boundary layer (ABL) has been developed and applied to study the effect of spatially variable surface properties on the areally averaged surface shear stress at the land-atmosphere interface. The LES code simulates the space and time evolution of the large-scale turbulent eddies and their transport effects in the ABL. We report here on simul...

We represent a theory of polymer gelation as an analogue of liquid-glass transition in which elastic fields of stress and strain shear components appear spontaneously as a consequence of the cross-linking of macromolecules. This circumstance is explained on the basis of obvious combinatoric arguments as well as a synergetic Lorenz system, where the strain acts as an order parameter, a conjugate...

We propose a scaling ansatz for the elastic energy of a system near the critical jamming transition in terms of three relevant fields: the compressive strain ∆φ relative to the critical jammed state, the shear strain , and the inverse system size 1/N . We also use ∆Z, the number of contacts relative to the minimum required at jamming, as an underlying control parameter. Our scaling theory predi...

Laminar free convection flow of viscous, incompressible fluid with variable viscosity and viscous dissipation through two horizontal parallel walls embedded in a porous medium is studied. Arrhenius model is used in which the variable viscosity is used to be decreasing exponentially with temperature. An approximation technique is defined to obtain the solution of the coupled non-linear equations...

Materials such as foams, concentrated emulsions, dense suspensions or colloidal gels, are yield stress fluids. Their steady flow behavior, characterized by standard rheometric techniques, is usually modeled by a Herschel-Bulkley law. The emergence of techniques that allow the measurement of their local flow properties (velocity and volume fraction fields) has led to observe new complex behavior...

1. Filamentous algae are widespread in freshwater ecosystems worldwide with a significant presence in streams, rivers and lakes with sufficient light and nutrients. Although typically not a preferred food source for grazers, dense filamentous mats provide surfaces for epiphytic microorganisms that are more palatable, thus adding to stream productivity. 2. We tested the hypothesis that epiphytes...

New analytic solutions for unsteady magnetohydrodynamic (MHD) flows of a generalized second-grade fluid have been derived. The generalized second-grade fluid saturates the porous space. Fractional derivative is used in the governing equation. The analytical expressions for velocity and shear stress fields have been obtained by using Laplace transform technique for the fractional calculus. The o...

Granular materials in a split-bottom ring shear cell geometry show wide shear bands under slow, quasi-static deformation. From discrete element simulations (DEM), continuum fields like the deformation gradient and stress can be computed with the goal to formulate objective constitutive relations for the flow behavior. From a single simulation only, by applying timeand (local) space-averaging, y...

Crack tip stress and deformation fields are analyzed for tensile-loaded ideally plastic crystals. The specific cases of (0 1 O) cracks growing in the [1 0 1] direction, and (1 0 1) cracks in the [0, 1, O] direction, are considered for both fcc and bcc crystals which flow according to the critical resolved shear stress criterion. Stationary and quasistatically growing crack fields are considered...

The objective of this study was to investigate the bacterial adhesion under different wall shear stresses in turbulent flow and using a diverse bacterial consortium. A better understanding of the mechanisms governing microbial adhesion can be useful in diverse domains such as industrial processes, medical fields or environmental biotechnologies. The impact of wall shear stress-four values rangi...