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Articles Published in Journal of Fluid Mechanics

  1. Meecham, W.C. and Jeng, D.T.. "Use of the Wiener-Hermite expansion for nearly normal turbulence" Journal of Fluid Mechanics. vol. 32. 1968. pp. 225--249.


  2. Crow, S.C. and Canavan, G.H.. "Relationship between a Wiener-Hermite expansion and an energy cascade" Journal of Fluid Mechanics. vol. 41. 1970. pp. 387--403.


  3. Wan, X. and Karniadakis, G.E.. "Stochastic heat transfer enhancement in a grooved channel" Journal of Fluid Mechanics. vol. 565. OCT 2006. pp. 255--278.

    We investigate subcritical resonant heat transfer in a heated periodic grooved channel by modulating the flow with an oscillation of random amplitude. This excitation effectively destabilizes the flow at relatively low Reynolds number and establishes strong communication between the grooved flow and the Tollmien-Schlichting channel waves, as revealed by various statistical quantities we analysed. Both single-frequency and multi-frequency responses are considered, and an optimal frequency value is obtained in agreement with previous deterministic studies. In particular, we employ a new approach, the multi-element generalized polynomial chaos (ME-gPC) method, to model the stochastic velocity and temperature fields for uniform and Beta probability density functions (PDFs) of the random amplitude. We present results for the heat transfer enhancement parameter E for which we obtain mean values, lower and upper bounds as well as PDFs. We first study the dependence of the mean value of E on the magnitude of the random amplitude for different Reynolds numbers, and we demonstrate that the deterministic results are embedded in the stochastic simulation results. Of particular interest are the PDFs of E, which are skewed with their peaks increasing towards larger values of E as the Reynolds number increases. We then study the effect A multiple frequencies described by a periodically correlated random process. We find that the mean value of E is increased slightly while the variance decreases substantially in this case, an indication of the robustness of this excitation approach. The stochastic modelling approach offers the possibility of designing `smart' PDFs of the stochastic input that can result in improved heat transfer enhancement rates.


  4. Lucor, D., Meyers, J., and Sagaut, P.. "Sensitivity analysis of large-eddy simulations to subgrid-scale-model parametric uncertainty using polynomial chaos" Journal of Fluid Mechanics. vol. 585. AUG 25 2007. pp. 255--279.

    We address the sensitivity of large-eddy simulations (LES) to parametric uncertainty in the subgrid-scale model. More specifically, we investigate the sensitivity of the LES statistical moments of decaying homogeneous isotropic turbulence to the uncertainty in the Smagorinsky model free parameter C-s (i.e. the Smagorinsky constant). Our sensitivity methodology relies on the non-intrusive approach of the generalized Polynomial Chaos (gPC) method; the gPC is a spectral non-statistical numerical method well-suited to representing random processes not restricted to Gaussian fields. The analysis is carried out at Re-lambda=100 and for different grid resolutions and C-s distributions. Numerical predictions are also compared to direct numerical simulation evidence. We have shown that the different turbulent scales of the LES solution respond differently to the variability in C-s. In particular, the study of the relative turbulent kinetic energy distributions for different C-s distributions indicates that small scales are mainly affected by changes in the subgrid-model parametric uncertainty.