[oliverwijaya]

Hi, I am doing a research in natural convection of lithium ion batteries (I simplified the model as a cylinder in a case) (picture 1). I already did the meshing in ICEM with good skewness and good orthogonal quality. I have some trouble when simulating my model in Fluent.
1. My residual value only shows the residual value of the energy, is that a problem ? (picture 2)
2. After I simulate the model, it appears the temperature contour is a bit strange, the heat flux didnt spread equally in the cylinder. (picture 2)

Does anyone ever had experienced in simulating something like these ?

Thanks !

[AlexanderZ]

how your domain looks like?
what kind of boundary condition did you apply

[oliverwijaya]

Originally Posted by AlexanderZ

how your domain looks like?
what kind of boundary condition did you apply

Hi Alexander ! Thank you for responding.

My domain looks like in the picture 3. It is only a simple box.

About the boundary condition, i applied wall BC for the case (domain) and heat flux wall for the cylinder (battery cells)

[AlexanderZ]

inside the box you should have fluid isn't it?

I wonder, why do you have such a low temperatures on the top (circle part) of cells. the difference for central cells is like 3000K on side and 300K on top

cells in the center should have higher temperate comparing to cells located close box walls. this is observed

plot fluid velocity contours

[LoGaL]

Seems to me a non converged simulation. How are you judging convergence? Just the energy residual?

[oliverwijaya]

Originally Posted by AlexanderZ

inside the box you should have fluid isn't it?

I wonder, why do you have such a low temperatures on the top (circle part) of cells. the difference for central cells is like 3000K on side and 300K on top

cells in the center should have higher temperate comparing to cells located close box walls. this is observed

plot fluid velocity contours

Yes i have working fluid inside the box, yeah that is the problem i havent solved why the top and bottom part has a low temperature. You can see in the picture I attached, the contour of wall heat flux is already constant in all of the surfaces

[oliverwijaya]

Originally Posted by LoGaL

Seems to me a non converged simulation. How are you judging convergence? Just the energy residual?

Hi Logal, yes the first simulation I forgot to turn on the gravity so the continuity and the velocity residuals doesnt show. Now it already showed but it only converged to 1e10-4. and still my problem havent solved yet

[AlexanderZ]

do you have space for fluid between cells and top\bottom walls of the box?
show xz view

[oliverwijaya]

yes, the cylinder didnt intersect with the walls

[AlexanderZ]

check material properties of cells, are you using orthotropic heat transfer coef?

and
cooling effect is too huge, from my point of view

[oliverwijaya]

Originally Posted by AlexanderZ

check material properties of cells, are you using orthotropic heat transfer coef?

and
cooling effect is too huge, from my point of view

i am assuming the battery cell as a wall with constant heat flux, and for this simulation i am doing natural convection with 0 pressure inlet and 0 pressure outlet