The engine used in this exercise is a direct-injection diesel engine with one main injection event. Its specifications are given in Table 1.1: Specifications of modeled DI diesel engine . The start of injection (SOI) occurs early during the compression stroke. The advantage of an earlier SOI is better mixing in the chamber, which provides a more homogeneous mixture prior to ignition. In conventional diesel engines, the SOI is very near top dead center (TDC).

Diesel engines are often modeled using a sector-mesh approach, and this exercise uses that method. The sector-mesh approach models only the in-cylinder processes. A sector can represent the full geometry since we can take advantage of the periodicity of the cylinder and injector nozzle-hole pattern. For example, an eight-hole injector allows simulation using a 45° sector (360°/8). By using the symmetry of the problem in this way, the mesh created is much smaller and the simulation therefore runs faster than it would with a 360° mesh. Such a simplification usually cannot be made for spark-ignited engine cases due to asymmetries introduced by spark plugs or intake flows.