Helideck Turbulence Study on Offshore Platforms by Anisotropic Turbulence Model

Abstract

The objective of this paper is to investigate the predictive capabilities of an anisotropic turbulence model for Helideck turbulence studies on offshore platforms and also to discuss the challenges in fulfilling the regulations and demands from the authorities for ensuring a safe helideck design. A Computational Fluid Dynamics (CFD) study is performed on a Front End Engineering Design (FEED) phase offshore platform geometry using unsteady Reynolds Stress model (RSM) [1] and the mean flow conditions for safe helideck operations are evaluated. The results are compared with an isotropic turbulence model using the realizable-kEpsilon (RKE) model [2] to establish if there is any gain or added merits in using computationally intensive RSM versus RKE model. The result comparison shows that for the skewed wind angles, flow separation from the platform outer edges will develop a swirl that starts to rise towards the helideck areas. This is well captured in the RSM model when compared to RKE model. In addition to numerical prediction, operational experience from pilots and their reactions to turbulence has also been documented in this paper. An open source software tool OpenFOAM is used in this study for the numerical analysis. As a part of this study, OpenFOAM has also been tested for canonical flows and the results are compared with experimental studies. Guidelines for evaluating helideck flow conditions and potential design modifications for safe helideck operations are also discussed in this paper.