Multiscale Modeling and Simulation

Organization:

Funded by: Philip Morris Products S.A.

PhD: David J. Lopez Penha

Supervisor: Bernard Geurts / Steffen Stolz

Collaboration: Philip Morris International Research & Development

**Description:**Porous materials are encountered in a wide variety of technologies. Many of these technologies employ porous materials for filtration, mixing (and reacting) or separation purposes. Some examples include: packed beds in chemical engineering and biological membranes/filters in biomedical engineering. A distinct feature of porous materials is their complicated pore structure. Transport processes (e.g., mass, momentum and energy) take place within an intricate network of three-dimensional, interconnected channels. Simulating these processes using well-known body-conforming grid methodologies poses a significant problem, i.e., the generation of grids of practicable quality. In general, these body-conforming grids are both difficult and time-consuming to produce. This research focuses on the development and application of a method that utilizes a nonbody-conforming representation of the flow domain. In particular, we develop and apply an immersed boundary (IB) method for simulating the dynamics of carrier fluids in biomaterials and their interactions with the underlying solid-pore matrix. The IB method eliminates the need for grid generation.

IB methods operate on highly efficient Cartesian grids, which, generally, are not aligned with the solid boundaries in the flow domain. Rather, IB methods rely on a source term in the equations of momentum transport to approximate no-slip boundary conditions at fluid-solid interfaces. Various forcing strategies are available for the IB method, one of the simplest is volume-penalization. Its source term is defined throughout the entire domain, including both the fluid and solid regions. The source term includes a phase-indicator function to help identify regions in the domain occupied by each phase; taking the value of ‘1’ in the solid parts and ‘0’ in the fluid parts of the domain. Therefore, parts of the domain occupied by a fluid experience no forcing; implying only the Navier-Stokes equations to be active. In stationary solid regions, the forcing function dominates the dynamics and forces the velocity to a negligibly small value. The volume-penalizing IB method is very versatile when it comes to accepting geometrical data, as this input enters through the phase-indicator function. Tests have indicated that this IB method shows first-order convergence of the solution. Research is being conducted on increasing solution accuracy and incorporating interacting physical processes, e.g., conjugate heat transfer and chemical species evolution (advection-diffusion-reaction modeling).

Fig.1: An example of a highly porous ceramic foam, also known as a reticulated porous ceramic (RPC). Clearly visible is the extreme internal pore complexity. Image source: <http://www.pre.ethz.ch/research/projects/?id=comptom >.

Presentation:

• An Immersed Boundary Method for Computing Anisotropic Permeability of Structured Porous Media.pdf 15 June 2009

Posters:

•Modeling Pore-Scale Transport in Realistic Porous Media Using an Immersed Boundary Method at Woudschoten conference 06 October 2010

•Multiscale Modeling and Simulation.pdf at Woudschoten conference 08 October 2009

PHD defense:

27 September 2012, 16.45 Hours “Simulating microtransport in realistic porous media”

Interview with MESA+ about the PhD project click here