Experimental 3D Velocity Field in Random Sphere Packing

Description

3D velocity fields obtained experimentally performing high resolution PTV in the bulk of a transparent porous medium at low Reynolds number (~10^-3). The porous medium is made out of a three dimensional random stack of monodisperse rigid spherical PMMA particles of diameter d = 2 mm. The sampled volume of porous medium is (5d*5d*9d), and the resolution is one pixel=d/120. The stationary flow is obtained by pushing fluid (seeded with passive fluorescent tracers) through the porous medium with an imposed flow rate. The velocity field is obtained by accumulating data over 1000 successive images in a slice of the porous medium. A PTV algorithm provides the fluid velocity within each pixel, thus outperforming most recent PIV techniques in terms of spatial resolution. The 3D velocity field is obtained by repeating the above 2D velocity field measurement over 50 slices spaced every d/10 = 200 um, in both the y and z-directions. Using linear interpolation we obtain the 3D velocity field over the whole sampled domain, where VX, VY, VZ are the velocity components in the x,y,z directions. Finally, a weighted divergence correction scheme is used to ensure the incompressibility of the 3D velocity field, while having negligible effect on the velocity distributions. The experimentally measured velocity fields are used to investigate dispersion, stretching, and mixing in porous media. This data set contains the 3D binary microstructure and the 3D divergence free velocity fields (both in raw format and Matlab format). Velocities are expressed in meter/sec, and the average velocity amplitude <U> = sqrt(VX^2+VY^2+VZ^2) = 127e-6 m/s. Datas has been used to develop Pore Aventura, a 3D velocity field explorer, that can be found on GitHub (https://github.com/Nico04/Pore-Aventura). For an introduction video, check (https://www.youtube.com/watch?v=NkHmAcAheAQ&feature=youtu.be) Data has been acquired in IUSTI Lab, UMR 7343, Aix-Marseille Université. Data set authors: Mathieu Souzy, Henri Lhuissier, Yves Méheust, Tanguy Le Borgne and Bloen Metzger. Main Related Publication : "Velocity distributions, dispersion and stretching in three-dimensional porous media", Journal of Fluid Mechanics, doi:10.1017/jfm.2020.113 Author contact : mathieu.souzy@gmail.com