Masters Theses

Keywords and Phrases

Non-intrusive polynomial chaos; Second-order probability


"A mixed aleatory (inherent) and epistemic (model-form) uncertainty quantification (UQ) analysis method was applied to a computational fluid dynamics (CFD) modeling problem of synthetic jet actuators. A test case, (Case 3, flow over a hump model with synthetic jet actuator control) from the CFDVAL2004 workshop was selected to apply the Second-Order Probability framework implemented with a stochastic response surface obtained from Quadrature-Based Non-Intrusive Polynomial Chaos (NIPC). Three uncertainty sources were considered: (1) epistemic uncertainty in turbulence model, (2) aleatory uncertainty in free stream velocity and (3) aleatory uncertainty in actuation frequency. Uncertainties in both long-time averaged and phase averaged quantities were quantified using a fourth order polynomial chaos expansion (PCE). Results were compared with experimental data available. A global sensitivity analysis with Sobol indices was utilized to rank the importance of each uncertainty source to the overall output uncertainty. The results indicated that for the long-time averaged separation bubble size, the uncertainty in turbulence model had a dominant contribution, which was also observed in the long-time averaged skin friction coefficients at three selected locations. For long-time averaged pressure coefficient, the contributions from free stream velocity and turbulence model are depending on the locations. The mixed UQ results for phase averaged x-velocity distributions at three selected locations showed that the 95% confidence intervals (CI) could generally envelope the experimental data. The Sobol indices showed that near the wall, the turbulence model had a main influence on the x-velocity, while approaching the main stream, the uncertainty in free stream velocity became a larger contributor. The uncertainty in frequency was found to have a very small contribution to both long-time averaged and phase averaged quantities with the range of variance considered"--Abstract, page iii.


Hosder, Serhat

Committee Member(s)

Riggins, David W.
Du, Xiaoping


Mechanical and Aerospace Engineering

Degree Name

M.S. in Aerospace Engineering


Missouri Research Board


Missouri University of Science and Technology

Publication Date

Fall 2011


xii, 125 pages

Note about bibliography

Includes bibliographical references (pages 56-62).


© 2011 Daoru Han, All rights reserved.

Document Type

Thesis - Open Access

File Type




Subject Headings

Actuators -- Testing
Analysis of variance
Computational fluid dynamics
Jets -- Fluid dynamics

Thesis Number

T 9926

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