Large Eddy Simulation of Flow over a Valve in a Simplified Cylinder Geometry

This study focuses on gaining a deeper understanding on the formation of turbulence and other in-cylinder flow structures caused by the intake jets during the intake stroke in internal combustion engines. This is important as the in-cylinder turbulence has a large effect on the mixing of fuel and oxidizer. A fine resolution large eddy simulation (LES) is carried out on an incompressible flow (Re is equivalent to 100,000) over a static valve (lift d = 7 mm) alongside with three other simulations using coarser meshes. The problem is studied in a simplified valve-cylinder geometry on which experimental data by Yasar et al., (2006) is available. The vortex cores, produced by the shear layer of the intake jets, are visualized using the λ₂ definition for vortex cores. The governing flow structures are identified and some features of the flow's mixing capabilities are observed. Additionally, the mixing is studied by releasing a passive scalar into to the flow. The simulations are carried out using the OpenFOAM CFD software with a transient solver for incompressible flows. The computational mesh is created with an automated grid generator, based on splitting of hexahedral cells, that allows the building of a mesh with an optimal cell size distribution for LES with high resolution near the wall and within the shear layer of the intake jets. The results of the simulation imply that the used numerical solution algorithm together with a novel grid generation strategy produces realistic results. The present work is one first studies that considers high resolution LES of an intake flow. The paper is the authoritative source for the abstract.