E. Migoya

Large-eddy simulation of spectral coherence in a wind turbine wake

This work is mainly dedicated to the study of the characteristics of spectral coherence of turbulence fluctuations in wind turbine wakes. A computational fluid dynamics (CFD) code has been implemented using a large-eddy simulation (LES) approach, which is thought to be conceptually more suitable for studying the turbulence evolution in a wind turbine wake. Comparisons with experimental data from the Norrekaer Enge II Windfarm, in Denmark, and with an analytical model proposed by Panofsky and Dutton have been performed, and the results are found to be in reasonable agreement with both.

THERMOCAPILLARY MIGRATION OF BUBBLES AT LARGE REYNOLDS NUMBERS

Abstract The thermocapillary movement of bubbles has been investigated for large Reynolds numbers. A numerical analysis of the flow field around a bubble has been carried out for arbitrary Marangoni (Ma) numbers. For small Ma the flow field has been calculated using a matched asymptotic procedure. A comparison is made of the nondimensional bubble velocity and the temperature gradient at the bubble surface, calculated numerically, with analytical results for large and small values of Ma, and with numerical results obtained previously. The expansion for large Ma has also been proposed by Balasubramaniam and Subramanian (1996) . For Ma⪢1 the presence of both the thermal boundary layer and the wake impose limitations in the numerical calculations. The calculations have been carried out for values of Ma significantly larger than those previously obtained.