Spatially resolved Pulsed Field Gradient (PFG) velocimetry techniques can provide precious information concerning flow through opaque systems, including rocks. This velocimetry data is used to enhance flow models in a wide range of systems, from oil behaviour in reservoir rocks to contaminant transport in aquifers. Phase-shift velocimetry is the fastest way to produce velocity maps but critical issues have been reported when studying flow through rocks and porous media, leading to inaccurate results. Combining PFG measurements for flow through Bentheimer sandstone with simulations, we demonstrate that asymmetries in the molecular displacement distributions within each voxel are the main source of phase-shift velocimetry errors. We show that when flow-related average molecular displacements are negligible compared to self-diffusion ones, symmetric displacement distributions can be obtained while phase measurement noise is minimised. We elaborate a complete method for the production of accurate phase-shift velocimetry maps in rocks and low porosity media and demonstrate its validity for a range of flow rates. This development of accurate phase-shift velocimetry now enables more rapid and accurate velocity analysis, potentially helping to inform both industrial applications and theoretical models.
Nanotechnology provides a lot of progress in all areas of engineering and technology. Similarly, in the field of lubrication, nano particles play vital role. It has been intensively evaluated in the last many years. Nano particles capable of improving the performance of lubricating oil. This review summarizes the morphological parameters of nanoparticles in the field of oil lubrication. Researchers studies various shapes, sizes and compositions of nanoparticles. This review is able to provide information about the morphological parameters of nanoparticles for better understanding of nano lubrication.
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