Large Eddy Simulation Of Turbulent Flow Over An Airfoil Using Both Structured And Unstructured Grids

Large Eddy Simulation of Turbulent Flow Over an Airfoil Using Both Structured and Unstructured Grids

This report describes the application of Large Eddy Simulations (LES) to turbulent flow over an airfoil. Two different approaches have been used, a second-order finite-difference solver on structured grid and a finite-element solver on unstructured grid. Results are presented for the flow around a NACA 4412 airfoil at maximum lift. The diversity of flow characteristics encountered in this flow include laminar, transitional and turbulent boundary layers, flow separation, unstable free shear layers and a wake. while Reynolds-averaged Navier-Stokes simulations (RANS) have had some success when tuned to flows dominated by one such flow characteristic, this variety of flow features taxes the presently available RANS models and presents an excellent opportunity to validate the utility of the dynamic SGS model for LES. Work has also been conducted on high order methods, both for the unstructured and the structured approach.

Large Eddy Simulation of Turbulent Flow Over an Airfoil Using Unstructured Grids

Many flows of aeronautical interest have regions where turbulence has a significant effect. For many of these flows, Reynolds-averaged Navier-Stokes simulation (RANSS) techniques do not give an acceptable description of the flow. In these cases a more detailed simulation of the turbulence is required. One such detailed simulation technique, large-eddy simulation (LES) has matured to the point of application to complex flows. Historically, LES have been carried out with structured grids which suffer from two major difficulties: the extension to higher Reynolds numbers leads to an impractical number of grid points, and most real world flows are rather difficult to represent geometrically with structured grids. Unstructured-grid methods offer a release from both of these constraints. Within this sponsored research significant progress has been made towards the application of the above approach to flows of aeronautical interest.

Large Eddy Simulation of Turbulent Flow Over an Airfoil