A frequency independent criterion to determine the limp model validity for highly porous sound absorbing materials is investigated. Although limp model is derived from the Biot theory assuming that the porous frame has no bulk stiffness, it is shown that this model can be used for highly porous materials since the criterion is respected. Abacus giving the criterion limit as function of the poro...

Based on an effective energy conversion method between gas enthalpy and thermal radiation, a multi-layered type of porous air heater has been proposed. In the five layered structure which is analyzed in this work, there are five porous layers which are separated by four quartz glass windows. The main layer operates as a porous radiant burner that products a large amount of thermal radiative ene...

Learners often struggle to grasp the important, central principles of complex systems, which describe how interactions between individual agents can produce complex, aggregate-level patterns. Learners have even more difficulty transferring their understanding of these principles across superficially dissimilar instantiations of the principles. Here, we provide evidence that teaching high school...

abstract bottom intake is one of the most appropriate systems for diverting discharge in steep rivers. bottom intake with porous media is a new system of diverting discharge which can be replaced by bottom rack intakes. to investigate the hydraulic flow characteristics on diverted discharge of this intake, an experimental model was designed in which the inflow, diverted discharge and remained f...

[1] We investigate the effects of the porosity (and thus permeability) of porous matrix and the fracture aperture on transport in fractured porous media. We do so with detailed lattice Boltzmann simulations on constructed porous media with a single fracture. Both plume spatial moments (the average plume velocity and the dispersion coefficients) and mass transfer coefficients between the facture...

A three-dimensional two-phase lattice Boltzmann model (LBM) is implemented and validated for qualitative study of the fundamental phenomena of liquid water transport in the porous layer of a proton exchange membrane fuel cell (PEMFC). In the present study, the three-dimensional microstructures of a porous layer are numerically reconstructed by a random generation method. The LBM simulations foc...

We investigated the implant-bone interface around one design of femoral stem, proximally coated with either a plasma-sprayed porous coating (plain porous) or a hydroxyapatite porous coating (porous HA), or which had been grit-blasted (Interlok). Of 165 patients implanted with a Bimetric hip hemiarthroplasty (Biomet, Bridgend, UK) specimens were retrieved from 58 at post-mortem. We estimated ing...

A numerical model is developed to simulate the transport phenomena in the flow channel between parallel plates with porous and non-porous (or impermeable) walls. The continuity and momentum equations were solved first, assuming the wall Reynolds number in the range of with the suction or injection of air at a speed equal to the uniform inlet velocity. The results show that at constant inlet and...

This paper presents a method for the fabrication of integrated porous silica layers in microfluidic channel networks by microfabrication techniques. Porous silica is obtained by anodization of silicon, followed by full conversion of the porous silicon network into porous silica by means of thermal oxidation. A series of experiments were performed with various channel layouts to determine the cr...