[suren1992]

Hello , I'm working with the simulation of the reactions occuring in a lead acid battery and the type of reaction considered for the simulation is wall surface reaction.

Geometry:(a screenshot of the geometry and mesh is attached)
2D
3 rectangles placed side by side : Anode - electrolyte - cathode

Mesh:
Used face meshing for all the 3 rectangles and the size of the mesh at the interface which is the smallest mesh size is about 1e-7 m.

Materials:
Fluid: H+, HSO4-, SO42-, H2O (last in the position of the materials)
Solid species: PbSO4, Pb, PbO2

Reactions considered for Fluent:
Anode: Pb + HSO4- = PbSO4 + 2e-
Cathode: PbO2 + HSO4- + 3H+ + 2e- = PbSO4 + 2H20

Problem :
The problem is, in the end of the simulation, the results showing a molar production of water at the anode eventhough there’s no water included in the reaction at the anode. And SO42- present in the materials as a spectator ions, but the result shows that there are some molar production and consumption of these ions eventhough I didnt include them in the reaction at the anode or the cathode. The result for the other substances are correct.
Would like to know if there's a way to solve this problem or any suggestions since i'm a beginner in simulation. Thank you in advance!

Settings considered for the simulation:
Time step size(s) = 1 (also worked with 1e-5(Adaptative) but had the same problem)
No. of time steps = 3600
Max iteration = 30
Time stepping method = Fixed
Solution Controls = 0.95 for all the reactants and products, as for the other values, they were maintained as the default values.
Initialization = Hybrid

[309558927]

You look like do something about the fuel cell,the caculation is so complex,because of the chemical recation,I have ever done a similar work using STAR CCM+ and ESI CFD,you can try.