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Swirl/tumble are rotational flow inside the combustion chamber. Fluent Computational Fluid Dynamics (CFD) software has been successfully used to simulate engine swirl and tumble flow. Two mesh approaches are possible within Fluent software to calculate transient engine swirl and tumble. One approach uses hybrid mesh with remeshing, while the other approach uses hex/wedge mesh with layering. The hybrid method employs tetrahedral remeshing, and is easier to set up compared to hex/wedge method for which only layering is used. Being easier to use, the hybrid method raises some concerns about result accuracy due to higher numerical diffusion associated with tet elements compared to the corresponding hex/wedge elements used for layering approach. This paper examines the two mesh approaches in terms of result accuracy for two engines, one SI and one diesel. The results are compared with PIV data for the SI engine.

Computational fluid dynamics (CFD) simulations of the transient flow-field around a generic side view mirror shape are presented that provide insight into the wind noise generated by the mirror. The generic mirror shape consists of half a cylinder, 0.2 m in diameter and length, topped with a quarter of a sphere of the same diameter. The transient flow past the generic side view mirror is simulated using the commercial CFD code Fluent with the LES turbulence model. A flow velocity of 200 km/hr is considered which correspond to a Reynolds number of 7 × 105. Detailed velocity vectors and contour plots of the time-varying velocity and pressure fields are presented along cut-planes in the flow-field. Mean and transient pressure are also monitored at several points in the flow field and compared to corresponding experimentally data published in literature. The results are also compared with predictions made using the Ffowcs-Williams-Hawkins acoustic analogy.