%0 Generic
%A Herzog, Alexandra Gabriela
%D 2010
%F heidok:11220
%K PLIF , Air-Water Gas Exchange , Wind-induced Turbulence , Free Surface , Waves
%R 10.11588/heidok.00011220
%T Imaging of Water-sided Gas-Concentration Fields at a Wind-Driven, Wavy Air-Water Interface
%U https://archiv.ub.uni-heidelberg.de/volltextserver/11220/
%X The aim of this study is to develop improved measurement techniques to determine depth dependent water-sided gas concentration fields under a winddriven free surface that is strongly wave-influenced. In comparison to previous studies the pH-LIF method was improved by using a novel fluorophore, a more powerful Laser and an optimized optical setup. This configuration allows for the first time high temporal resolution imaging of concentration fields under a strongly wave-influenced surface in two spatial dimensions. Two measurement techniques based on Laser-induced fluorescence have been improved and developed, respectively: On the one hand, the theory of a spectral reconstruction approach was improved, that allows an arbitrary orientation of the illuminated cross section. Here, depth-dependent concentration fields can be estimated by inverse modeling. On the other hand, a novel measurement technique, static pattern LIF (SP-LIF), has been developed from side-LIF by applying a discretized illumination. For the first time, a reliable estimate of the water surface even under a nearly vanishing near surface concentration gradient, has become possible. Now, the found and classified coherent structures in the near surface turbulence under wind shear can be compared to the results of direct numerical simulations to reveal the dominating transport mechanisms under varying conditions.