I'm running into the Floating Point Error in ANSYS Fluent. I've imported a model of a fiber structure that I have encased in "fluid". To do this, I extruded a volume over the space of the fiber model on a different plane and used a Boolean operation to differentiate the two. I'm just changing the element size for meshing. I've also created named sections by selecting the face of a fiber strand and applying it to all surfaces at that x, y, or z coordinate, so I'm fairly certain the fibers and fluid surfaces make contact. In Fluent, I'm running at steady state while using the energy equation and laminar-viscous model. The fluid (air) in this analysis is to be stagnant, so I'm treating that volume as a solid with air properties. I've applied a temperature of approximately 660 K to the top surface and 400 K to the bottom surface. The other four side wall surfaces are at a constant heat flux of 0. All other walls/contacts are set to coupling. I'm using hybrid initialization and when I run the calculation, my residuals (only energy) shoot way up after maybe 80 iterations. If I allow the calculation to continue, I am prompted with the floating point error. I've even relaxed energy to 0.3. Any ideas on what my issue could be and how to fix it? I'll attach a few images to give a better idea of what I'm doing.
Mesh with the surrounding fluid
Mesh with the fluid hidden
This is a static temperature contour plot of the interfaces. You can see there is some slightly warmer areas on the top face, but heat isn't moving like it should. This was only after 13 iterations.
This is the same plot, but of the fluid walls.
I'd appreciate any help, If you need more information just let me know. Thank you!