### 9.8.3. Spark Ignition Model

The spark ignition model is available only for transient simulations.

#### 9.8.3.1. Spark Kernel

Set Kernel Center and Initial Volume to the location and the initial size of the spark. Set Transition Radius to control when the transition from the spark model to the regular combustion model to occur. The transition radius should be sufficiently large such that the transition region can be resolved by the mesh.

#### 9.8.3.2. Ignition Time

Specify the time for spark ignition to occur.

#### 9.8.3.3. Spark Energy

Optionally, the electrical energy of the spark may be included into the model. The energy of the spark can be defined by one of the following:

- Spark energy (specifies the total energy of the spark)

- Spark power (energy flux) and duration of the spark

The Electrode Efficiency parameter controls the fraction of the spark energy introduced into the fluid. The complementary fraction is modeled to be lost to the external world by heat transfer in the spark electrode.

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