Development of the Sensors

In order to quantifly and handle the errors and uncertainties arising, sensors for their detection were developed and implemented. These sensors scan the boundary layer and flow field to ascertain the level of adherence to relevant best practice guidelines. These sensors are developed and calibrated on the basis of a generic test case using a reference solution with minimal error. A sensitivity study with isolated mechanisms was carried out first of all, following which the interaction of errors was investigated for mixed errors. The results were parameterized to give simple expressions for the error magnitude as a function of the relevant sensor output. The applicability of these derived functions to more complex test cases is tested.

1.1 Development of the Error Sensors

At the beginning of the investigation the grid convergence study was performed on the flat plate test case (Re = 2.1e6, Ma = 0.1, u0 = 33m/s) with a fully structured grid. For this the turbulence model of Spalart-Allmaras with Edward-modification (SAE) was used, which is the specified standard model in TAU. The grid expansion ratio near the wall and the wall distance y0 of the wall nearest grid point were varied until there were no significant changes in the solution. The hereby identified grid was used as a reference grid and as a basis for the further investigations. For all investigations eight different turbulence models were applied — two one-equations models (SAE and Spalart-Allmaras (SAO)), three two-equation models (Wilcox k – ю, Menter-SST und LEA к-ю) and three EARSM models (Rung RQEVM, Wallin & Johannson 2D Mean Flows (WJ2D) und Hellsten EARSM к-ю).