Mathematical Problems in Engineering
Volume 2009 (2009), Article ID 394387, 26 pages
Research Article

Higher Period Stochastic Bifurcation of Nonlinear Airfoil Fluid-Structure Interaction

Faculty of Aerospace Engineering, Delft University of Technology, Kluyverweg 1, 2629HS Delft, The Netherlands

Received 1 February 2009; Accepted 11 March 2009

Academic Editor: José Roberto Castilho Piqueira

Copyright © 2009 Jeroen A. S. Witteveen and Hester Bijl. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The higher period stochastic bifurcation of a nonlinear airfoil fluid-structure interaction system is analyzed using an efficient and robust uncertainty quantification method for unsteady problems. The computationally efficient numerical approach achieves a constant error with a constant number of samples in time. The robustness of the method is assured by the extrema diminishing concept in probability space. The numerical results demonstrate that the system is even more sensitive to randomness at the higher period bifurcation than in the first bifurcation point. In this isolated point in parameter space the clear hierarchy of increasing importance of the random nonlinearity parameter, initial condition, and natural frequency ratio, respectively, even suddenly reverses. Disregarding seemingly less important random parameters based on a preliminary analysis can, therefore, be an unreliable approach for reducing the number of relevant random input parameters.