Aspects of the recursive projection method applied to flow calculations
Joakim Möller · 2005
In this thesis, we have investigated the Recursive Projection Method, RPM, as an accelerator for computations of both steady and unsteady ows, and as a stabilizer in a bifurcation analysis. The criterion of basis extraction is discussed. It can be interpreted as a tolerance for the accuracy of the eigenspace spanned by the identied basis, alternatively it can be viewed as a criterion when the approximative Krylov sequence becomes numerically rank decient. Steady state calculations were performed on two dierent turbulent test-cases; a 2D supersonic nozzle ow with the Spalart-Allmaras 1-equation model and a 2D sub-sonic airfoil simulation using the k model. RPM accelerated the test-cases with a factor between 2 and 5. In multi-scale problems, it is often of interest to model the macro-scale behavior, still retaining the essential features of the full systems. The coarse time stepper is a heuristic approach for circumventing the analytical deriv-