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Item type:Publication, Access status: without files , Data-driven gust modeling and adaptive wind tunnel control using offshore field data from the Baltic Sea(American Society of Mechanical Engineers (ASME), 2026-06); ; 10 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Assessment of wind gust effects on the flow around offshore helidecks using RANS simulations(American Society of Mechanical Engineers (ASME), 2026-06); ; ; Wind gusts can significantly affect the flow characteristics above offshore helidecks, with direct implications for the operability and safety of helicopters. In this paper, RANS simulations using k–ω SST turbulence model are performed to investigate the influence of wind gusts on the mean flow field above a converter platform helideck. Idealized gusts are defined using field-measured characteristics from the Baltic Sea, and the gust response is analyzed through phase-interval averaged quantities and assessed using relevant metrics. The results show that gust forcing induces an increase in the mean turbulence kinetic energy and flow velocity magnitude with respect to the baseline mean flow. Across the investigated wind directions, turbulence kinetic energy generally increases over gust phases, with the strongest response occurring during the phase following the gust peak velocity. Critical wind directions for helicopter operations are identified for the configurations in which the helideck is located in the flow stagnation region, and the separated shear layer from the helideck interacts with the wakes from the surrounding superstructures. The results also highlight the importance of accounting for unsteady inflow conditions, showing that steady inflow simulations can lead to differences in the estimated kinetic energy values of turbulence during gust events.Publicationtype: Conference Paper16 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Numerical and experimental investigation of the tip vortex flow induced by an elliptical foil(HAL science ouverte, 2024-11-13); ; ; ; This collaborative paper within the AVT-320 joint research activity compares Computational Fluid Dynamics (CFD) results from diverse methods across research partners, validated against Experimental Fluid Dynamics (EFD) investigations in two test facilities. Focusing on non-cavitating tip vortex flows using an elliptical foil as a test case, the study reveals flow fluctuations and highlights the synergy between research institutions and advanced measurement technologies. The evaluation of CFD methods, including hybrid RANS/LES-numerical approaches, provides insights into turbulence modeling for tip vortex flows. Strong interactions between the tip region and trailing edge flow are observed, contributing to refining our understanding of these complex fluid dynamics. The study includes a comprehensive analysis of the tip vortex behavior of the the elliptical foil NACA 662-145, which has been investigated over the past three decades. The collected data encompasses the distribution of 19 flow variables on 17 cross sections, with a detailed analysis and comparison performed on four planes. Experimental results elucidate the effects of wandering correction on variable distribution. Two approaches to model turbulence are employed in CFD computations: scale-resolved simulation models to characterise the local flow and the eddy viscosity-based k − ω SST model. The hybrid turbulence model ensures consistency in velocity and pressure in the core region, serving as a robust reference for cavitation inception.Publicationtype: Working Paper73 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Characteristics and consequences of vortex wandering around a ship hull at drift: a numerical study(2022-07-01); ; ; The present paper investigates the major trailing vortex next to the KVLCC2 hull at 30°static drift and ReLoa≈2.6⋅106. Numerical simulations of a single-phase flow with the SST-based IDDES model are conducted with OpenFOAM. Proper orthogonal decomposition reveals the transverse displacement at the vortex centre. Spectral analysis indicates both the presence of a low-frequency broadband wandering motion and the existence of a distinct amount of turbulence at the centre by a broad inertial subrange. Tracking the instantaneous vortex centre in time reveals that the amplitude in relation to the core size is comparable to the far-field wingtip vortex studied by Devenport and colleagues in 1996. A new observation is the significant bending of the vortex axis. This reveals difficulties for the use of vortex planes being corrected for wandering. Following the correction is restricted to the vortex centre. One consequence of wandering is that about two thirds of resolved TKE can be attributed to it.Publicationtype: Journal Article99 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Experimental Investigation on the Wake of the Japan Bulk Carrier Model with Stereoscopic and Tomographic Particle Image Velocimetry(2022-06); ; To provide reliable turbulence data for validating computational fluid dynamics solvers, extensive experimental investigations are conducted on the wake of a double-body model of the underwater hull of the Japan Bulk Carrier without appendages in straight ahead and drift conditions in the low speed wind tunnel of TUHH. The investigation focused on capturing and tracking the After-Body (ABV) and Fore-body Side (FSV) vortices, using a Tomographic Particle Image Velocimetry (TPIV) system. The results of the investigation are compared with the results of an earlier investigation conducted in the same facility using a Stereoscopic Particle Image Velocimetry (SPIV) system in both straight ahead and drift condition. The results were compared additionally to the results of the investigation conducted by National Maritime Research Institute (NMRI) and Osaka University (OU) in a towing tank using a SPIV system for the straight ahead condition. In addition, this paper provides data for local flow fields and turbulence with high temporal and spatial resolution for future comparisons.Publicationtype: Conference Paper118 100 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Experimental study of the wake of a truncated wall-mounted circular cylinder at high Reynolds numbers(Elsevier, 2022-03-23); ; ; ; The paper presents the Particle Image Velocimetry (PIV) analysis of the wake of the wall mounted truncated cylinder with an Aspect Ratio (AR) of 4 at a range of high Reynolds numbers from 6.4*10 4 to 2.41*10 5 . The velocity distributions are measured using a two-dimensional three-components PIV(2D-3C PIV) system in two horizontal sections. In order to choose a proper measurement window,preliminary smoke tests are conducted. The snapshots of the velocity field are subjected to the Proper Orthogonal Decomposition (POD) analysis in order to understand the structure of the unsteady flow.The influence of the Reynolds number on the POD modes and the distribution of the fluctuation energy among the velocity components are studied. Additionally, a so-called amplitude analysis for each of the first three strongest modes is conducted in order to give a physical interpretation to each of them. The mode structures have been found to remain similar in the mention Re range, so the complete description of the POD results is given for Re = 1.28*10 5 . The most modes are connected to symmetric (about x-axis) fluctuations of the wake in transversal, vertical or longitudinal directions. At the top of the cylinder the wandering and the change of the tip vortices’ (TV) intensity also contribute to the fluctuation energy. In the considered measurement windows the modes which could be associated with the von Karman vortex shedding have not been identified.Publicationtype: Preprint40 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Numerical investigation of the JBC hull and propeller interaction under static drift conditionAs outlined in the Tokyo CFD Workshop 2015, reliably reproducing the turbulent kinetic energy and vorticity in the wake of the Japan Bulk Carrier (JBC) hull is still a challenge to contemporary CFD methods (Hino, et al., 2021). Depending on the applied turbulence modeling approach, a wide variance of fluid characteristics can be observed. In numerical simulations, the accuracy of resolving the stationary vortices induced along the ship hull and quantifying their strength is part of current research investigations (see Visonneau, et al., 2016, Shevchuk, et al., 2016). This topic is especially important for the static drift condition, under which the vortical structures can have a significant influence on the interaction between the hull and propeller and lead to high fluctuations of propeller and hull drift forces. The objective of this study is the numerical investigation of the hull-propeller interaction of the JBC hull under static drift condition. Taking the propeller into account leads to two different scenarios that are investigated: positive and negative drift. This results in two operational conditions of the propeller. Within the numerical study a RANS approach as well as DES methods are applied in order to investigate the influence of the applied turbulence model on the flow structure. The numerical model is validated based on extensive results from the Tomographic Particle Image Velocimetry measurements with and without propeller, which are presented and compared to the CFD results. A detailed analysis of hull and propeller forces will be presented in this paper.Publicationtype: Conference Paper89 134 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Experimental and Numerical Studies of the Flow Around the JBC Hull Form at Straight Ahead Condition and 8 degrees Drift AngleThis paper presents the new experimental and computational data on the JBC (Japan Bulk Carrier) hull form at straight ahead condition and 8◦ drift angle obtained at Hamburg University of Technology. The experiments were conducted on a double-hull model in a wind tunnel using the PIV technique. Good agreement with the results of other institutions (OU, NMRI) for the straight ahead condition is attained. The simulations at straight course are performed employing two different hybrid approaches, which are compared to each other and to the experimental results in terms of integral and distributed flow quantities. The more reliable approach (SST-DDES - SST-based Delayed Detached Eddy Simulation) is selected for further simulation of the flow at pure drift condition. In all cases a good agreement between the experimental and numerical results for most quantities is observed. However, the numerically predicted TKE levels on fine meshes turn out to be too high compared to the experimentally obtained ones and are attributed to the deterioration of shielding properties of the DDES delay function on finer meshes.Publicationtype: Conference Paper142 131 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: with files , Fore-body side vortex of KVLCC2 at 30° drift: A trailing vortex resolved with DES and compared to PIV data(Scientific Research Publishing, 2019-10-30); ; ; 4 4