Numerical Simulation of Multiphase Flow in Porous Media

Nathaniel Morgan, Georgia Institute of Technology

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Multiphase heat-transfer offers superior cooling performance over single-phase convection. A new approach to cooling heat-generating elements is to couple porous materials with two-phase convection; this combination provides additional structural support for the element along with extremely efficient heat transfer capabilities. Various applications ranging from high-frequency windings to electronics will benefit from this cooling technology. However, little is still understood about phase transition in porous media, and the modeling capabilities are extremely limited. Advances in computational fluid dynamics are essential for accurately predicting and characterizing the cooling performance of a particular design.

The two major challenges in developing a direct numerical simulation (DNS) of two-phase flow in porous media are (1) accurately handling the arbitrary geometries that accompany a porous structure, and (2) the liquid-vapor interface. A remedy to these challenges is to model both the liquid-vapor interface and the solid-fluid interface using the level set framework. The complicated geometries are handled by using a level-set field that is stationary, along with an immersed boundary technique that guarantees a sharp solid-fluid interface. Likewise, the liquid-vapor interface is captured implicitly using the standard level-set method on a structured mesh. Representing each interface with a level-set field allows the Navier-Stokes equations to be solved on a structured mesh using standard single phase solvers, which greatly reduces the complexity of modeling two-phase flows through porous structures.

Abstract Author(s): Nathaniel Morgan, Marc Smith, Mostafa Ghiaasiaan