Electrical Mesh

The electrical mesh defines cells on the battery stack or jellyroll strip. Each cell in the electrical mesh represents an ecell in the electrical calculation. Although you must define the electrical mesh dimensions, it is created internally and cannot be visualized.

The initial resolution for the electrical mesh depends on the battery model that is selected in Simcenter Battery Design Studio, and is read into Simcenter STAR-CCM+ during the import process. The electrical mesh is used during the simulation only for the electrical calculations; a thermal mesh is used for the energy calculations.

The X and Y dimensions that are specified in Simcenter Battery Design Studio are the number of nodes in each dimension. In Simcenter STAR-CCM+, the values of node-based fields (such as ohmic heat and current fields) are present on the electrical grid at the X and Y dimensions that are specified in Simcenter Battery Design Studio. However, the number of e-cells in the X and Y dimensions is two less than the number of nodes, so the e-cell grid has dimensions of X-2, Y-2. This specification applies to e-cell values, such as SOC and polarization heat.

You can change the resolution of the electrical mesh to suit the requirements of your simulation. See Battery Cells Reference.

Within Simcenter Battery Design Studio, the specified electrical mesh dimensions are used to compute the resolution that Simcenter STAR-CCM+ uses for its electrical solver. The actual dimensions are derived from the specified resolution and the minimum number that is feasible based on the layout of the jellyroll and tabs.

Typically, the electrical mesh is less dense than the thermal mesh or the surrounding fluid mesh. For many applications, it is recommended that you start by using a coarse electrical mesh and increase the mesh density only if necessary. For a stacked cell, a coarse electrical mesh is 10x10x1 or less. The solution time varies linearly with the addition of battery cells to a battery module.

For a stacked cell, you set the value of the electrical mesh resolution in the Z-direction, according to the thickness of the battery cell. For thin cells, there is no advantage in using more than one ecell as there is not normally a significant temperature gradient in the normal direction.

For a spiral cell, the minimum mesh resolution is determined automatically in Simcenter Battery Design Studio based on the layout of the cell. If the specified resolution is lower than this minimum, Simcenter Battery Design Studio increases it accordingly. For a stacked cell, the minimum mesh resolution is 1x1x1.

The thermal mesh for the battery cell is defined separately in Simcenter STAR-CCM+ in a mesh operation on the geometry. Mesh settings for other parts of the battery, such as tabs and connectors, are also defined in a mesh operation on the geometry.