Reply on RC2

Abstract

Abstract. This study investigates the impact of microstructure geometry on the thermal and turbulence responses of fiber-optic (FO) cables under varying flow conditions and turbulence intensities. The underlying measurement principle is the directionally sensitive heat loss from electrically heated FO cables with imprinted microstructures exposed to turbulent airflows resembling a long hot-wire anemometer. Using the COMSOL Multiphysics 6.0 finite-element software, this study explores a wider range of different configurations of filled and hollow filled-coned microstructures of varying size compared to existing studies. The research identifies optimal combinations which maximize temperature differences (∆T) across FO cables with cones pointing in opposite directions while balancing key design criteria such as sensitivity to wind speed and minimizing the cables’ PVC coverage. We demonstrate that FO cables with hollow-coned microstructures (radius = 24 mm, height = 24 mm, and spacing = 15 mm) outperform their filled-coned counterparts, maintaining ∆T values above 2 K across a broader range of wind speeds and turbulence intensities. Notably, the hollow-cone configuration sustains a temperature difference of up to 0.8 K at a 60(°) wind attack angle. The findings implicate substantial improvements for an optimized FO cable design in atmospheric boundary layer studies, enabling more accurate measurements of wind direction, distributed turbulent heat fluxes, and vertical wind speed perturbations using fiber-optic distributed sensing (FODS). Future work shall validate the findings under field conditions to assess the robustness and real-world applicability of the optimized design.

Authors 1

1. Mohammad Abdoli corresponding Aachen Physical Geography and Climatology

   RWTH Aachen University · University of Bayreuth

   Affiliation as printed

   Micrometeorology Group, University of Bayreuth, Universitätsstraße, 95447 Bayreuth, Bavaria, Germany

   Physical Geography and Climatology, RWTH Aachen University, Wüllnerstraße 5b, 52062 Aachen, North Rhine-Westphalia, Germany