An adjoint-based Navier-Stokes design and optimization method for two-dimensional multi-element high-lift configurations is derived and presented. The compressible Reynolds-Averaged Navier-Stokes (RANS) equations are used as a flow model together with the Spalart-Allmaras turbulence model to account for high Reynolds number effects. Using a viscous continuous adjoint formulation, the necessary ...

An adjoint-based Navier-Stokes design and optimization method for two-dimensional multi-element high-lift configurations is derived and presented. The compressible Reynolds-Averaged Navier-Stokes (RANS) equations are used as a flow model together with the Spalart-Allmaras turbulence model to account for high Reynolds number effects. Using a viscous continuous adjoint formulation, the necessary ...

Large Eddy Simulation (LES) and Reynoldsaveraged Navier-Stokes (RANS) calculations have been used to predict the development, separation, reattachment and downstream recovery of the flow over a smoothly contoured ramp. The statistically two-dimensional upstream flow separates along the ramp surface and then reattaches downstream on a flat section. A canonical flatplate turbulent boundary layer ...

Most mathematical models include parameters that need to be determined from measurements. The estimated values of these parameters and their uncertainties depend on assumptions made about noise levels, models, or prior knowledge. But what can we say about the validity of such estimates, and the influence of these assumptions? This paper is concerned with methods to address these questions, and ...

The simulation of turbulent boundary layers requires quite detailed inflow information since the resolved flow is unsteady and three-dimensional. Rather than simulating laminar and transitional regions arising near a leading edge, it is often more computationally efficient to formulate a fully turbulent inflow condition. To date, three types of methods for creating appropriate inflow conditions...

A fast Newton–Krylov algorithm is presented that solves the turbulent Navier–Stokes equations on unstructured 2-D grids. Themodel of Spalart andAllmaras provides the turbulent viscosity and is loosely coupled to themean-flow equations. It is often assumed that the turbulence model must be fully coupled to obtain the full benefit of an inexact Newton algorithm. We demonstrate that a loosely coup...

The separation of a turbulent boundary layer, which is encountered in devices such as airfoils, diffusers and turbomachinery, is one of the most challenging research topics in fluid mechanics. Its understanding and its prediction with turbulence models are however still not satisfactory. The reason may be partly due to a shortage of reliable data from numerical simulations, which account for Re...

Tillage has long been an essential component of traditional agricultural systems. Broadly defined, tillage is the mechanical manipulation of the soil and plant residues to prepare a seedbed for crop planting. The benefits of tillage are many: it loosens soil, enhances the release of nutrients from the soil for crop growth, kills weeds, and regulates the circulation of water and air within the s...