Fig. 4: Flame propagation near top dead center (TDC) in a compression ignition engine simulation between t = −2.0 and t = 2.0 crank angle degrees (CAD) after TDC (aTDC).
From: End-to-end modeling of fuel injection via static coupling of internal flow and ensuing spray
Iso-surfaces of temperature identify the flame front, while the fuel spray parcels are colored by their velocity. a-c Computational fluid dynamics (CFD) predictions obtained using the rate of injection (ROI) approach. d-f CFD predictions obtained using the one-way coupling approach. With one-way coupling, due to the transient widening of the spray, many parcels are injected to the sides where drag effects become relatively more important and cause the droplet to slow down considerably (cf. black parcels). These parcels are also more likely to impinge on the cylinder head creating a fuel film that persists during the early stages of the combustion, as visible from the visualization in subfigure (f).
