Showing 2 results for Porous Media
H Gh, H Sadeghi,
Volume 7, Issue 1 (8-2013)
Abstract
Wave velocity and attenuation are among the most important attributes of stress waves that propagate through geomaterials. Utilizing these attributes, it is possible to acquire useful information about porous geomaterials such as soil and rock and also the fluids that saturate the pores of geomaterials. The key point in order to gain this information is to establish an accurate link between field measurements of wave attributes and physical properties of geomaterials’ skeleton and pore fluid. The pore fluids and their inhomogeneous distribution fluid are among factors that affect wave velocity and attenuation to a considerable extent. Patchy saturation of pores which occurs on the scale larger than grains size but smaller than wavelength is one of the reasons that causes inhomogeneity in pore fluid distribution. The influence of such inhomogeneity is studied in present paper. Two different attenuation mechanisms including relative movement of fluid with respect to solid phase and also attenuation caused by grain to grain contact are implemented to fully assess wave attenuation. It is observed that the former attenuation is more dominant at higher frequencies compared to the latter attenuation.
H Salamat Ravandi, Mh Kharazi Fard, Mr Majdzadeh Tabatabaee,
Volume 7, Issue 2 (3-2014)
Abstract
River bank erosion is a mechanism initiated by soil particles movement due to subsurface flow. This may occur in a soil texture at a critical hydraulic gradient. With regard to the complexity of river bank erosion processes and limited research in this field, it is of significance to investigate and to identify the effective parameters. In the present study, a physical model of a river bank was developed to achieve in-depth understanding of the effects of bank material particle sizes on porous media under various hydraulic gradients. It is concluded that the length of scour hole caused by seepage erosion may depend on the hydraulic gradients as well as Reynolds number. Further, two empirical relationships are derived on the basis of observed experimental results to estimate scour hole length resulted from river bank erosion for laminar and turbulent conditions
