3d Measurements Of Nano-Particle Transport In Complex 2.5d Micro-Models

A confocal Micro-Particle Image Velocimetry (C-mu PIV) technique along with associated post image processing algorithms is established to quantify three dimensional distributions of nano particle velocity and concentration at the micro-scale (pore scale) in 2.5D porous media designed from a Boise rock sample. In addition, an in-situ, non-destructive method for measuring the geometry of the micro-model, including its depth, is described and demonstrated. The particle experiments use 900 nm fluorescence labeled polystyrene particles at a flow rate of 10 nLmin(-1) and confocal laser scanning microscopy (CLSM), while in-situ geometry measurements use regular microscope along with Rhodamine dye and a depth-to-fluorescence-intensity calibration. Image post-processing techniques include elimination of background noise and signal from adsorbed nano-particle on the inner surfaces of the micro-model. In addition, a minimization of depth of focus technique demonstrates a capability of optically thin slice allowing us to measure depth wise velocity in 2.5D micro-model. The mean planar components of the particle velocity of the steady-state flow and particle concentration distributions were measured in three dimensions. Particle velocities range from 0.01 to 122 mu m s(-1) and concentrations from 2.18 x 10(3) to 1.79 x 10(4) particles mm(-2). Depth-wise results show that mean velocity closer to the top wall is comparatively higher than bottom walls, because of higher planar porosity and smooth pathway for the nano particles closer to the top wall. The three dimensional micro-model geometry reconstructed from the fluorescence data can be used to conduct numerical simulations of the flow in the as-tested micro model for future comparisons to experimental results after incorporating particle transport and particle-wall interaction models.