We developed a numerical method for computing the effective properties of a microstructure. The method is particularly efficient and accurate for microstructures with a diffuse-interface description similar to those generated from phase-field simulations. In particular, we considered the diffusive transport property of a microstructure by solving the steady-state diffusion equation using a Four...

We have constructed tapered fiber-optic microsensors with a tip diameter of less than 10 microm to measure profiles of backscattered light in biofilms, which are thin layers of micro-organisms firmly attached to surfaces. The observed response agrees well with local effective diffusivity microelectrode measurements, with R(2) > 0.85. A strong relation between signal intensity and wavelength has...

Nutrient concentration profiles are affected by the mass transport outside the biofilm, inside the biofilm, and by the structure of the biofilm. To understand the distribution of biofilm activity, it is necessary to correlate the local nutrient concentration, local mass transport in the biofilm and the biofilm structure. The correlations among surface averaged dissolved oxygen concentration, su...

Axial diffusion in a two-dimensional channel of smoothly varying geometry can be approximately described as one-dimensional diffusion in the entropy potential with position-dependent effective diffusivity by means of the modified Fick-Jacobs equation. In this paper, Brownian dynamics simulations are used to study the range of applicability of such a description, as well as the accuracy of the e...

We consider the motion of a particle in a periodic two dimensional flow perturbed by small (molecular) diffusion. The flow is generated by a divergence free zero mean vector field. The long time behavior corresponds to the behavior of the homogenized process that is diffusion process with the constant diffusion matrix (effective diffusivity). We obtain the asymptotics of the effective diffusivi...

energy and mass transfer investigations in thermal processing of fruits serve as a breakthrough in the design and scale up of drying systems. diffusivity characteristics and specific energy consumption for drying of fig fruit in a laboratory scale microwave dryer were assessed. several intervals for microwave power intensity including 0.5, 1, 1.5, 2, and 2.5 w g-1, and 6 levels of power on-off ...

This paper studies the influence of convection by periodic or cellular flows on the effective diffusivity of a passive scalar transported by the fluid when the molecular diffusivity is small. The flows are generated by two-dimensional, steady, divergence-free, periodic velocity fields.

A simple-to-fabricate woven mesh, consisting of bonded laminates of two-dimensional plain-weave conductive screens is described. Geometric equations show that these porous matrices can be fabricated to have a wide range of porosity and specific surface area, . A heat transfer model is developed. It shows that the laminates can have a highly anisotropic thermal conductivity vector, with in-plane...

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