Meaning
Computational algorithm that calculates the temperature distribution across a battery system by progressing through time in small, discrete increments without solving a simultaneous system of equations. This mathematical approach determines the state of the system at the next time step based solely on the known values of the current step. An explicit thermal solver is highly effective for simulating fast, transient events such as thermal runaway or high energy impacts where temperature changes occur in microseconds.
The method remains stable only when the time step is smaller than a specific physical limit known as the Courant condition.
Numerical Procedure
Calculation of the heat flux at each node depends on the temperature gradients established in the previous interval. Using an explicit thermal solver allows for a highly parallelized computation because the update for one element does not require the simultaneous values of its neighbors. This efficiency makes it suitable for complex three dimensional geometries with non linear material properties.
Stability Constraint
Time step size must remain extremely small to prevent numerical oscillations from growing and ruining the simulation. When an explicit thermal solver is applied to a large battery pack, the total number of iterations can become very high even for a short real time event. Engineers often use mass scaling or other techniques to manage the computational cost while maintaining physical accuracy.
Transient Analysis
Rapid temperature spikes during a short circuit event are captured with high fidelity using this direct temporal integration. Because an explicit thermal solver does not require the inversion of a large matrix, it handles the sudden changes in heat generation kinetics better than steady state methods. The result provides a detailed map of how heat propagates from one cell to the next during a propagation failure.
