The Prospect and Benefits of Using the Partial-Averaged Navier-Stokes Method for Engine Flows 2020-01-1107
This paper presents calculations of engine flows by using the Partially-Averaged Navier-Stokes (PANS) method . The PANS is a scale-resolving turbulence computational approach designed to resolve large scale fluctuations and model the remainder with appropriate closures. Depending upon the prescribed cut-off length (filter width) the method adjusts seamlessly from the Reynolds-Averaged Navier-Stokes (RANS) to the Direct Numerical Solution (DNS) of the Navier-Stokes equations. In the conventional well-established PANS, the unresolved to total kinetic energy ratio fk known as the cut-off control parameter, is calculated from the grid spacing and the computed integral turbulence length scale. Several formulations have been derived up to now. In most of these formulations, fk is obtained by summing up the resolved turbulence, while the unresolved motion is computed from the modelled equation. The PANS method was successfully used on large number applications but mainly on static geometries, e.g. ; . This is due to calculations of the resolved kinetic energy which is obtained by suitably averaging of the resolved field. Such averaging process is expensive and impractical for engines as it would require averaging per cycles. A recently published work on PANS  opens up a prospect of more cost-effective engine calculations. This new PANS approach solves the additional equation for a total resolved turbulent kinetic energy which enables continuous (in situ) update of the resolution parameter fk. Thus fk. is dynamically specified in time and space depending on the flow and computational meshes. Calculation results of the IC engine  will be compared with the measurements which include cycle-to-cycle variations and emission measurements. Large-Eddy Simulation (LES) results will also be used to evaluate potential benefits of the PANS method for engine calculations.