Learning Forum

[luc.bernhardt]

Hi everyone,

I’m currently running a CFD simulation to analyze the heat transfer in a battery segment composed of lithium cells. Here are the key details of the setup:

Model: k-epsilon turbulence model with energy equation enabled.
Heat source: On each cells, defined as a source term corresponding to the power dissipated in the cells, specified in W/m³ based on use cases.
Mesh: Focused on the positions of the cells, with a volume enclosure around the segment.
Boundary conditions:
Inlet: Velocity of 7 m/s with an air temperature of 35°C.
Outlet: Pressure outlet with air exiting at 35°C.
The simulation runs fine overall, and the air temperature rises as expected while passing through the segment. However, I’m observing an issue: the cells closest to the inlet are unexpectedly the hottest.

I’ve checked the inlet and outlet configurations, and they seem correct since the air is clearly heating as it moves through the segment. The mesh quality is good as well. I also have the radial and axial thermal conductivity values and the specific heat of the cells.

Does anyone have an idea what could be causing this behavior? Could it be related to turbulence modeling, heat transfer mechanisms, or something I might have overlooked?

Thanks in advance for your help!

[luc.bernhardt]

Here are a screenshot of the results and boundary conditions.

[Rob]

Can you plot temperature contour & velocity vectors on the fluid (only) for the z mid-plane? I agree in that I'd expect the inlet end to be coolest, but with only one image diagnosing why is impossible.