Wave and transport phenomena through porous media are of great importance in science and industrial applications, because they involve the interaction of various physical mechanisms and can provide useful informations of the structure of the porous medium. Despite the extensive application in modern industry and comprehensive research, transport and wave propagation through porous materials are not fully understood. This work focuses on the investigations of hydraulical and acoustical properties of sintered glass bead systems, which serve as replacement for rock samples. In contrast to common rock samples the hydraulical and acoustical properties of the sintered glass bead samples can be selectively influenced by the selection of certain glass beads and sintering treatments. Moreover, their high gray-scale contrast to the pore space, in addition to the relatively simple pore structure favors their use in scientific research and image analysis. The research goal is to understand the essential physical phenomena and mechanisms, which determine the transport and wave behavior in fluid-saturated porous sintered glass bead systems. For this purpose, a multi-purpose measuring cell is developed, which enables, besides stationary and dynamic permeability measurements, also to perform ultrasound experiments, while the produced porous sintered samples can be saturated with different fluids. The steady-state and oscillatory flow processes through sintered glass bead packings, are investigated, in order to determine both, the stationary and frequency-dependent hydraulic properties. For the ultrasound experiments the porous sintered samples are either saturated with Newtonian fluids, like water or silicone oil, or with magnetorheological fluids (MRF), which is a suspension of micron-sized, magnetizable particles in a silicone-oil-based carrying fluid. The wave propagation in MRFsaturated porous sintered samples is studied at different magnetization strengths. The ultrasound experiments are performed according to the transmission method and analyzed using the spectral ratio technique. The ultrasound experiments reveal nicely the dispersive nature of the fluid-saturated sintered granular materials and show strong frequency filtering as the dispersion properties of the detected waves are highly influenced by the pore fluid. The experimental studies of transport and waves are complemented by extensive research on the morphology by using XRCT-based images of the produced samples. A special focus lies on the elaborate μXRCT data processing of the produced samples. The proposed frameworks for μXRCT analysis can be used for arbitrary porous media. The binarized and differently-sized voxel data are incorporated in Lattice Boltzmann simulations to determine the local permeabilities numerically and finally are compared with experimental effective permeabilities. The numerical permeabilities are correlated with averaged microscopic features, such as pore throats.
|Award date||30 Jun 2016|
|Place of Publication||Enschede|
|Publication status||Published - 30 Jun 2016|