17.9 Contact Resistance at Walls

ANSYS FLUENT's solidification/melting model can account for the presence of an air gap between the walls and the solidified material, using an additional heat transfer resistance between walls and cells with liquid fractions less than 1. This contact resistance is accounted for by modifying the conductivity of the fluid near the wall. Thus, the wall heat flux, as shown in Figure  17.9.1, is written as

where $T$, $T_w$, and $l$ are defined in Figure  17.9.1, $k$ is the thermal conductivity of the fluid, $\beta$ is the liquid volume fraction, and $R_c$ is the contact resistance, which has the same units as the inverse of the heat transfer coefficient.

Figure 17.9.1: Circuit for Contact Resistance