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Multi-dimensional modelling of the flow and combustion promises to become a useful optimisation tool for IC engine design. Currently, the total simulation time for an engine cycle is measured in weeks to months, thus preventing the routine use of CFD in the design process. Here, we shall describe three tools aimed at reducing the simulation time to less than a week. The rapid template-based mesher produces the computational mesh within 1-2 days. The parallel flow solver STAR-CD performs the flow simulation on a similar time-scale. The package is completed with COVISEMP, a parallel post-processor which allows real-time interaction with the data.

Numerical simulations of diesel engine combustion and emission formation have been performed using a detailed soot model. Operating conditions typical for modern truck-size engines have been investigated, and calculated results show encouraging agreement with experimental data for soot in engine exhaust gas. Predictions of details in the soot formation process compare well with detailed experimental data from the literature. The modelling of the soot/flow-field interaction is based on a flamelet approach. Source terms of the soot volume fraction are taken from a flamelet library using a presumed probability density function and integrating over mixture fraction space. In order to save computer storage and CPU time, the flamelet library of sources was constructed using a multi-parameter fitting procedure resulting in simple algebraic equations and a proper set of parameters.