See also: porous bone cement injection in medical physics

Complex physics in porous media

Unlike many other CFD tools, our software generates the computational mesh itself - fast and efficiently, in a time negligible compared to the actual simulation. The simplicity of setting up a numerical problem is particularly striking in a complex geometry.

Next follows an animation of a water-air multi-phase flow inside the Berea sandstone produced by the lattice Boltzmann CFD software library Palabos. The porosity of the medium was 20%. The full simulation domain was 3.6 mm wide and 4.0 mm high. The simulation lattice was comprised by 400 x 400 x 444 nodes. This was a high-resolution simulation to demonstrate the multi-phase capabilities of the Palabos solver. The water-air interface is shown as the fluid marches inside the medium.

 

The next animation concerns the capillary/viscous fingering of a non-wetting buoyant fluid (red) through a crystalline porous structure (gray) that is initially saturated with a more viscous and denser fluid (transparent). The porous medium has an approximate porosity of 35%, and opens in a crystal-free environment that is initially completely occupied by the dense fluid. At the porosity transition, because of the sudden change in confinement, capillary forces break the capillary fingers into bubbles that buoyantly rise through the crystal-free environment.

Multi-phase flow in a crystal. Courtesy of Dr. Andrea Parmigiani and Dr. Sébastien Leclaire.
 

On the left side of the video we see only the non-wetting buoyant fluid, while on the right side we can additionally see: (1) the geometry of the environment (high crystallinity at the bottom, crystal-free at the top) and (2) the magnitude of the velocity field. The calculation was performed with a lattice Boltzmann recoloring method on a grid size of 150 x 150 x 550 nodes. The viscosity ratio between the two fluids was set to 100, and the Bond number for this multi-phase flow was equal to 0.3.

In the following demo, the porous medium is originally saturated with water, and oil is injected from the bottom. The velocity in the water is shown as the oil invades the porous medium.

 
Our software is all about complexity. The following example combines the physics of 3D two-phase flow in a pore-scale porous medium with a melting process in the third, solid medium. The example also includes heat convection, as the mechanism of melting is connected to the temperature in the liquid phases.
 
Multi-phase flow in a melting chamber. Courtesy of the University of Geneva.

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