Abstract When a pair of tandem cylinders is immersed in flow the downstream cylinder can be excited into wake-induced vibrations (WIV) due to interaction with vortices coming from upstream cylinder. Assi, Bearman & Meneghini ( J. Fluid Mech. , vol. 661, 2010, pp. 365–401) concluded that WIV excitation mechanism has its origin unsteady vortex–structure encountered by as it oscillates across wake. In present paper we investigate how responds excitation, characterising amplitude and...

Direct stability analysis and numerical simulations have been employed to identify characterize secondary instabilities in the wake of flow around two identical circular cylinders tandem arrangements. The centre-to-centre separation was varied from 1.2 10 cylinder diameters. Four distinct regimes were identified salient cases chosen represent different scenarios observed, for each configuration detailed results are presented compared those obtained a an isolated cylinder. It observed that...

Floating offshore wind turbines (FOWTs) are subjected to platform motion induced by and wave loads. The oscillatory movement trigger vortex instabilities, modifying the wake structure, influencing flow reaching downstream turbines. In this work, of a FOWT is analysed means numerical simulations comparison with linear stability theory. Two simplified models based on vortices developed for all degrees freedom turbine motion. our simulations, blades modeled as actuator lines spectral-element...

The possible states in the flow around two identical circular cylinders tandem arrangements are investigated for configurations vicinity of drag inversion separation. By means numerical simulations, hysteresis transition between shedding regimes is studied and relationship (three-dimensional) secondary instabilities regime determination addressed. differences observed behavior two- three-dimensional flows analyzed, regions bistable delimited. Very good agreement found proposed scenario...

The wake transition of the flow around two circular cylinders placed in staggered arrangements with fixed streamwise separation 5 D and cross-stream varying from 0 to 3 has been studied. is compared that a single isolated cylinder. Linear stability analysis utilizing Floquet theory direct numerical simulations using spectral/hp element spatial discretization were carried out. unstable modes first appear cylinder, which are long-spanwise-wavelength mode A short-spanwise-wavelength B, also...

We evaluate the accuracy of actuator line model (ALM) approach by performing simulations for NREL~5~MW wind turbine in uniform inflow using three large eddy simulation codes. The power and thrust coefficients obtained codes agrees within $1\%$ when grid spacing $\Delta_{\rm grid} \le 5.25$~m, are cross-validated against blade element momentum (BEM) theory. find that results ALM converge towards BEM theory without need tip correction numerical resolution is increased. For grid}=0.98$~m...

This paper thoroughly investigates the onboard generator and energy storage systemsets section for offshore platform supply vessels (PSVs), aiming to optimize fuelefficiency, reduce emissions, enhance operational reliability. The study employs adetailed analysis of various PSV phases, assessing different setconfigurations exploring impact battery integration.The commences with a focus on selecting generators based demandcurve, revealing substantial fuel savings exceeding 19% during periods...

Abstract. In wind energy research, scientific challenges are often associated with complex terrain sites, where orography, vegetation, and buildings disrupt flow uniformity. However, even sites characterized as simple can exhibit significant spatial variability in speed, particularly during stable boundary layers (SBLs) low-level jets (LLJs). This study investigates these interactions using both simulations observations from the American WAKe ExperimeNt (AWAKEN). We employ a multiscale...

ABSTRACT Sensitivity analysis plays a vital role in understanding the impact of control parameter variations on system output, particularly cases where an objective functional evaluates output's merit. The adjoint method has gained popularity due to its efficient computation, especially when dealing with large number parameters and few functionals. While discrete form is prevalent, exploring continuous counterpart can offer valuable insights into underlying mathematical problem,...

In previous work, comparisons were made between large-scale simulations of the American Wake ExperimeNt (AWAKEN) wind farms conducted using large-eddy simulation (LES) codes Nalu-Wind and Adaptive Mesh Refinement-Wind, engineering farm model FLOw Redirection Induction in Steady State (FLORIS), multi-scale Weather Research Forecasting model. Significant discrepancies observed modeled wake deficits, present paper investigates sources this variability new with single turbines smaller domains....

Abstract A simple way to decrease the drag and oscillating lift forces in flow around a circular cylinder consists of positioning splitter plate wake, parallel flow. In this paper, effect on wake dynamics, more specifically transition, is described detail. First, two-dimensional three-dimensional direct numerical simulations (DNS) using spectral element method were used observe behaviour presence plate. Then, linear stability analysis based Floquet theory was performed order obtain...

Greenhouse gas emissions are one of the most critical worldwide concerns, and multiple efforts being proposed to reduce these emissions. Shipping represents around 2% global CO 2 Since ship power systems have a high dependence on fossil fuels, hybrid using diesel generators batteries becoming an interesting solution In this article, we analyze potential implementation Li-ion in platform supply vessel system through simulations HOMER software (Hybrid Optimization Model for Multiple Energy...

The main objective of this paper is to select the optimal configuration a ship’s power system, considering use fuel cells and batteries, that would achieve lowest CO2 emissions also taking into consideration number battery cycles. ship analyzed in work Platform Supply Vessel (PSV) used support oil gas offshore platforms transporting goods, equipment, personnel. proposed scheme considers retrofitting. original generators are maintained, cell batteries installed as complementary sources....

Abstract This paper presents the modeling, simulation and optimization of a single channel proton exchange membrane fuel cell (PEMFC) using computational fluid dynamics methods. The shape flow‐channels was employed to improve electrical performance cell. maximization current density objective function single‐objective problem, upper lower widths flow channels were control variables cross‐section area restriction imposed. optimized flow‐channel PEMFC presented improved generation...

The nonlinear character of the primary bifurcation is investigated for flow around a flexibly mounted circular cylinder. We have considered cases in which cylinder can oscillate transverse direction only and both in-line directions. Low high values mass ratio ( $m^{\ast }=5$ 50) were studied, reduced velocity $V_{r}$ ) are chosen inside $V_{r}=9$ outside $V_{r}=5$ $V_{r}=13$ lock-in range low Reynolds numbers. For each combination }$ , global linear stability analysis was applied to find...

Brazil is currently witnessing the dawn of its offshore wind industry, and companies, government, investors, society must understand risks possible environmental impacts this technology can generate. This paper aims to partially fill need by presenting an analysis that would be caused a 5 MW floating turbine installed on Brazilian continental shelf through Environmental Impact Assessment (EIA) Life Cycle (LCA). We assumed supply electrical power oil gas extraction platform, with intention...