Batteries General Workflow

When simulating batteries in Simcenter STAR-CCM+, follow the steps in this workflow.

Simcenter STAR-CCM+ provides the option to use either 3D battery cells that you import from Simcenter Battery Design Studio, or 0D cells that you can create directly in Simcenter STAR-CCM+. When you create a 0D battery cell in Simcenter STAR-CCM+, you can choose to define the cell manually or use parameters that are extracted from a .tbm file.
To set up an electro-thermal battery simulation, do one of the following—then follow the appropriate steps for the 0D or 3D battery cells throughout the workflow:
  • For 0D battery cells, start at step 1
  • For 3D battery cells, start at step 2
  1. Import the battery geometry of a full battery pack including the cells, or create the geometry in 3D-CAD.
    If you use battery cells that you create directly in Simcenter STAR-CCM+, the geometry should contain suitable parts to represent each battery module cell, tabs, connectors, casing, and any cooling plates or channels as required.
  2. Set up the physics continua.
    1. For battery cell continua, select the following physics models along with any others as required:
      Group Box Model
      Space Three Dimensional
      Material Solid or Multi-Part Solid
      Time Implicit Unsteady
      Optional Models Battery
      Circuit Model (selected automatically)
      Energy Segregated Solid Energy
      Gradients (selected automatically)
      Equation of State Constant Density
    2. Select any optional models as required. It is recommended that you select the following models to aid solution accuracy.
      • Cell Quality Remediation
      • Solution Interpolation
    3. For tabs and connectors, or other solid parts such as cooling plates or casing, select the following models:
      Group Box Model
      Space Three Dimensional
      Material Solid
      Time Implicit Unsteady
      Optional Models Segregated Solid Energy
      Gradients (selected automatically)
      Equation of State Constant Density
      Optional Models Select any optional models as required. It is recommended that you select the following models to aid solution accuracy.
      • Cell Quality Remediation
      • Solution Interpolation
    4. Select any optional models as required. It is recommended that you select the following models to aid solution accuracy.
      • Cell Quality Remediation
      • Solution Interpolation
    5. If you want to consider fluid flow, for example the flow of a coolant, create a physics continuum for the fluid and select the required models.
  3. Define the material properties.
    1. Expand the Continua > Battery > Models > Solid (or Multi-Part Solid) node and define the properties of the battery material, such as the specific heat and thermal conductivity.
    2. Check and edit the material properties for the other materials in the battery as required, such as the tabs and connectors, cooling plate/coolant, and casing.
  4. Define the battery cells.
    To Create 0D battery cells directly in Simcenter STAR-CCM+ To Import 3D battery cells from Simcenter Battery Design Studio
    This method allows more freedom to modify specific settings and use custom geometry for cells. Optionally, you can choose to use settings previously specified in a .tbm file. The battery can be defined using the RCR model. If you want to model thermal runaway, you can select the Heat Release model and the Vent model.
    1. Right-click the Batteries > Battery Cells node and select Create User-Defined Battery Cell.
    		 This method allows you to use pre-defined battery cells. There are less settings to define, however, there is less flexibility to modify the settings/geometry within Simcenter STAR-CCM+.
    1. Right-click the Batteries > Battery Cell node and select Create from Tbm.

      See Creating Battery (.tbm or .ebm) Files in Simcenter Battery Design Studio.

    2. In the Import Battery Data From File dialog, select a .tbm or .ebm file and click Open.

      Simcenter STAR-CCM+ automatically recognizes the cell models, updates the appropriate properties of the battery cell, and reads in the mesh settings that are specified in the Battery model.

    3. In the Import Battery Options dialog, ensure that the battery parts that you want to import are selected (you can exclude some optional parts and replace them with your own geometry) then click OK.

      Simcenter STAR-CCM+ reads the dimensions of the cell from the .tbm or .ebm file and generates an idealized battery cell 3D-CAD model.

      Simcenter STAR-CCM+ also automatically creates physics continua with appropriate physics models.
    See Battery Cells Reference: 0D Battery Cells. See Battery Cells Reference: 3D Battery Cells.
  5. Set up the battery modules.
    See Battery Modules Reference
    Using 0D battery cells Using 3D battery cells
    1. Right-click the Batteries > Battery Modules node and select New > User-Defined Battery Module.
    2. Select the Batteries > Battery Modules > Battery Module node and set the properties as required—in particular, N Series and N Parallel.

      The correct number of cells appear under the Battery Module > Battery Module Cells node.
    1. Right-click the Batteries > Battery Modules node and select New > TBM Battery Module.
    2. Select the Batteries > Battery Modules > Battery Module node and set the properties as required—in particular, N Series and N Parallel.
    3. Select the Battery Module > Module Configuration node and set the Battery Cells.
    4. Check and update any properties under the Battery Module sub-nodes as required.
    See Battery Modules Reference: Battery Modules That Use 0D Cells. See Battery Modules Reference: Battery Modules That Use 3D Cells.
  6. Assign the battery cell geometry parts to the battery module cells.
    Using 0D battery cells Using 3D battery cells
    1. Right-click the Batteries > Battery Modules > Battery Module node and select Assign Parts to Battery Module Cells by Name.
    2. In the Assign Parts to Battery Module Cells by Name dialog, assign the battery parts to their respective battery module cells.
      • When using the default setting Assign by Mapping, you specify which sequential numbers in the part names represent the parallel string numbers (Parallel Occurrence) and series string numbers (Series Occurrence), then you select all parts that represent battery module cells and click the right arrow .Simcenter STAR-CCM+ automatically assigns parts to the battery module cells. However, if the string numbers in the part names do not correspond directly with those in the battery module cell names, you specify the Parallel Offset and Series Offset to guide Simcenter STAR-CCM+ to convert the numbers from the part name to the numbers in the corresponding battery module cell name.
      • When using Assign Manually, you select parts on the left and battery module cells on the right, then click the right arrow . You can select multiple parts and battery module cells—the assignment happens from the top to the bottom of both selections.
    For more information, see Battery Modules Reference: Assign Parts to Battery Module Cells by Name.
    1. Right-click the Batteries > Battery Modules > Battery Module node and select Generate Battery Parts.

      The Geometry > Parts node is automatically populated with the battery parts that are designed in Simcenter Battery Design Studio.

    2. If required, to create tab connectors, right-click the Batteries > Battery Modules > Battery Module node and select Generate Connector Parts.
  7. Create the circuit.
    注You do not need to configure a circuit when modeling thermal runaway in 0D battery cells. You can disable the Circuit model, if you prefer.
    1. Define the required circuit elements.
      See Circuit Elements Reference.
      When defining battery modules that use 0D cells, you can multi-select the battery modules, then use the right-click options to automatically create series or parallel connected circuit elements from the modules.
      See Battery Modules That Use 0D Cells.
      Make sure that you also include one of the following circuit elements to define an electrical load on the battery:
      • Program File

        Specifies a load for a particular duration. For example, 10 amps for 10 seconds, then 8 amps for the next 20 seconds, and then 6 amps for the next 30 seconds.

      • Table

        Each table row specifies a load at a particular time. The interval between specified time values can be flexible: you do not need to specify values at regular time intervals. However, the load values are linearly interpolated between the specified time values to provide data at the time step of the thermal solver. Due to this interpolation, using a table to define a load can provide more flexibility than using a program file.

      • Scalar Function

        Specifies a load as a scalar function. The scalar function can be a constant value or an expression which is evaluated over time. The expression can use field functions that you define.

    2. Connect the circuit elements.
    For detailed instructions about setting up electrical circuits, see Creating Electric Circuits.
  8. If you want to create multiple battery modules and set up the battery pack, do the following:
    • Duplicate the battery modules manually by using the Copy and Paste technique.
    • (For battery modules created from 0D battery cells only) Right click the Batteries > Battery Modules > Battery Module node and select Create User-Defined Battery Pack.

      In the Create User-Defined Battery Pack dialog, you then specify the number and arrangement of battery modules in the battery pack and, optionally, create the connecting circuits and assign cell geometry parts to the modules.

      See Battery Modules Reference: Create New User-Defined Battery Pack.



  9. If required, create or define the external casing.
    Using 0D battery cells Using 3D battery cells
    When using the 0D battery cells approach, there is no specialized workflow required for creating the battery casing. If the geometry, physics continua, and region are not already defined for the battery casing, then create them now—if required.
    1. Select the Battery Module > External Casing Geometry > External Casing Specification node and select the option that you require.

      See Battery Modules Reference.

    2. Right-click the Batteries > Battery Modules > [battery module] node and select Create External Casing Part.

      Simcenter STAR-CCM+ creates a bounding box, or takes the selected casing part, and subtracts the battery module parts from it. The resulting part is named Battery Module: External Casing
  10. Assign parts to regions.
    Using 0D battery cells Using 3D battery cells
    1. Multi-select the Geometry > Parts > [part] nodes, then right-click one of the nodes and select Assign Parts to Regions.
    2. In the Assign Parts to Regions dialog, select the appropriate parts and set the options as required for the regions, boundaries, part curves, and the interface type.
    3. Click Apply and Close.
    1. Right-click the Batteries > Battery Modules > [Battery Module] node and select Assign Parts to Regions.
    2. In the Assign Battery Parts to Regions dialog, select the appropriate parts and set the options as required for the regions, boundaries, part curves, and the interface type.
    3. Click Apply and Close.

    By default, each battery region is defined as a battery energy source. Regions that are created for the tab parts are ohmic heat sources and the region for the stack is both a polarization heat source and an ohmic heat source. These settings are defined automatically when the regions are generated, and do not need to be changed. Regions that are created for the tab connectors are not defined as battery energy sources.

    See Assign Parts to Regions Reference
    Make sure that all battery cell parts are assigned to a battery region and that the interfaces are created as expected (between parts that are in contact).
  11. Assign physics continua to the appropriate regions. Select each of the Regions > [region] nodes and set the Physics Continuum as necessary.
  12. Create the mesh.
    The thin parts of a battery (such as tabs and connectors) benefit from using the Thin Mesher. The Thin Mesher recognizes thin parts of geometries and produces prismatic cells within the thin parts. For non-thin parts of the geometry, the Thin Mesher automatically changes to produce polyhedral (or tetrahedral) cells. The mesh remains conformal.
    When following the 3D battery cell workflow, Simcenter STAR-CCM+ automatically creates a mesh operation that contains the appropriate models, settings, and custom controls required to mesh a battery—Surface Remesher, Automatic Surface Repair, Polyhedral Mesher, and Thin Mesher.
    Using 0D battery cells Using 3D battery cells
    1. Right-click the Geometry > Operations node and select New > Mesh > Automated Mesh.
    2. In the Create Automated Mesh Operation dialog, select all of the parts that require meshing, and select the meshers (for example, Surface Remesher, Automatic Surface Repair, Polyhedral Mesher, and Thin Mesher).
    3. Click OK.
    4. Expand the Geometry > Operations > Automated Mesh Operation node and set the default controls as required.
    5. It is recommended to create a custom volumetric control to refine the mesh of the tabs and connectors—with a mesh size that is roughly 4% of the tab stem height.
    6. To generate the volume mesh, right-click the Geometry > Operations node and select Execute All.
    For further guidance, see Meshing.    		 You can follow the same method as for meshing 0D battery cells, or use the provided battery mesher. To change the pre-defined battery meshing settings as necessary before you generate the mesh.
    1. Right-click the Batteries > Battery Modules > [Battery Module] node and select Set Up Battery Parts Meshing.
    2. Expand the Geometry > Operations > Mesh Battery Module > Meshers node and make any necessary adjustments to the mesher properties.

      Make sure to maintain a volumetric control to refine the mesh of the tabs and connectors.

    3. Create automated mesh operations for any non-battery parts.
    4. To generate the volume mesh, right-click the Geometry > Operations node and select Execute All.
    The refinement of the mesh in the connectors helps with the convergence of the energy solver when the Ohmic Heating model is turned on.
  13. Optionally, you can set up ohmic heating to account for the ohmic heating effect in the tab connectors when a current passes through them.
    Using 0D battery cells Using 3D battery cells
    When using the 0D battery cells approach, there is no specialized workflow required for setting up the ohmic heating. If you want to account for Ohmic heating, you include the Ohmic Heating model in the physics continuum for the tabs and connectors—defined in earlier steps. You can create reports and field functions to check for current conservation in and out of the cell at the posts for the negative tab and positive tab respectively. Right-click the Batteries > Battery Modules > [battery module] node and select Set Up Connector Ohmic Heating.
    Simcenter STAR-CCM+ creates:
    • Two reports for the current and interface surface area: BatteryCellCurrent and TabStem_Post_Intersect_Area
    • Current density field functions from the reports: CurrentDensityToApplyToConnector_IN and CurrentDensityToApplyToConnector_OUT.

      The field functions are automatically applied to the appropriate interfaces—where they compute the current density, with one for current flowing in and the other for current flowing out. These values are of equal magnitude but opposite sign. The definition for the positive current density is ($BatteryCellCurrentReport / $TabStemAreaReport). The convention is to have the positive current density represent the current flowing in. The current flows into the post for the negative tab and flows out of the post for the positive tab.
  14. Set the initial conditions.
    1. Expand the Continua > [continuum] > Initial Conditions nodes for each continuum
    2. Set appropriate values for the initial starting conditions, such as the static temperature.
  15. Define the solver settings.
    As a result of non-converged initial electric potential, spurious heat is introduced into the Segregated Energy solver in the first iterations of an analysis. This behavior can lead to high temperatures in intermediate non-converged states. To improve convergence of the Segregated Energy solver:
    1. For the Segregated Energy solver, set a Solid Under-Relaxation Factor of 0.9999.
    2. Select the Segregated Energy > Solid Under-Relaxation Factor Ramp node and set Ramp Method to Linear Ramp, then set the Linear Ramp properties:
      Start Iteration 6
      End Iteration 10
      Initial Value 1.0 E-7
    3. Specify any other solver settings as required.
      When using the Distributed 3D model, see Adjusting Battery Settings for the Distributed 3D Model.
  16. Set up post-processing.
    You can create many types of monitors, plots, reports, or scenes to display various outputs from battery cells, for example:
    • Scalar scenes to view specific parts or plane sections through parts, such as the temperature in the centre of a battery module or at the outlet of a cooling channel.
    • Plots from reports, such as the state of charge, temperature, current, etc. See Battery Model Reference: Field Functions.
    • Create multiple reports, monitors, and plots from battery modules. See Create Battery Module Reports....
    • Animations to watch a charge and/or discharge cycle of a battery. See Animating Solution Views.
    For more information, see Post-Processing.

    When following the 3D battery cell workflow, Simcenter STAR-CCM+ automatically creates the BatteryCellCurrent and TabStem_Post_Intersect_Area reports. The battery cell current report is a volume average report that collects the current going through the cell. The battery module stack or the jellyroll region is automatically assigned to it. The tab stem/post intersect area report returns the area of the intersection between the stem and the post for the stacked cell, and end plate and post for the cylindrical cell.

If a battery cell state of charge reaches 0% or 100%, the simulation results can become unphysical, but the simulation can continue to run. If the battery cell uses a physical model (such as the DISTNP model), the simulation stops automatically when the state of charge reaches 0% or 100%. However, if the battery cell uses an empirical model (such as the NTG model or the RCR model), the state of charge of the cell becomes fixed at 0% or 100%. The simulation continues to run, but uses the constant value that the model computes at the fixed state of charge. Obviously, a real battery cell does not do this. If you want your simulation to stop when the state of charge of any battery cell reaches 0% or 100%, you can set the appropriate stopping criteria.
  1. When using an empirical model, to stop the simulation when the minimum state of charge is reached, do the following:
    1. Right-click the Reports node and select New Report > User > Minimum.
    2. Set Scalar Field Function to Battery > Battery SOC and set Parts to the region that represents the jellyroll (the state of charge is defined only on the jellyroll region).
    3. Right-click the Reports > [report] node and select Create Monitor and Plot from Report.
    4. Right-click the Stopping Criteria node and select New Monitor Criterion, then in the Select Monitor dialog, select [Minimum Monitor] and click OK.
    5. Select the Stopping Criteria > [Minimum Monitor Criterion] node and deactivate Stop Inner Iterations.
    6. Select the Stopping Criteria > [Minimum Monitor Criterion] > Minimum Limit node and set the Minimum Value as a percentage of the cell capacity.
  2. Set any other stopping criteria as required.
    See Setting Up Stopping Criteria.
  3. Save the simulation.
  4. Run the simulation.