Numerical Simulation of Water Circulation In Marinas of Complex Geometry By A Multi-block Technique

International audienceThis paper presents a finite-volume method for solving the Shallow-Water Equations (SWE) in a curvilinear coordinate system on an arbitrary overlapping composite grids. A multi-block technique is implemented. The academic tests are also presented to validate the proposed technique. A typical application of this technique is the simulation of water circulation in marinas and harbor

Tidal Asymmetry and Suspended-Sediment Transport in the Gironde Estuary (FRANCE)

Source: ICHE Conference Archive - https://mdi-de.baw.de/icheArchiv

Three-dimensional modelling of turbine wake interactions at a tidal stream energy site

One of the biggest uncertainties in tidal stream energy resource assessment is how tidal energy conversion, particularly at large scale, will interact with the resource. As few arrays are currently operational, data collected from these developments tends to be commercially sensitive. Therefore, array interaction with the resource is generally assessed using numerical models. A fully three-dimensional numerical approach based on Actuator Disk theory was implemented into the Regional Ocean Modelling System (ROMS) to simulate the energy extraction by tidal stream turbines. Emphasis was placed on wake interactions and cumulative effects of individual devices on energy extraction at array scale. This model was applied at the tidal stream energy site of the Fromveur Strait (western Brittany, France) considering an array of horizontal-axis turbines of 10-m diameter, matching the device technology currently operating in the Strait. Two tidal energy metrics were considered to describe asymmetries in tidal current magnitude and direction. The area with reduced asymmetry in current magnitude was selected to implement the turbine array. A nested grid technique was adopted to cascade processes from the regional scale to the high-resolution local farm domain. The computation was conducted over the inner-nested array domain covering the tidal farm with horizontal and vertical resolutions of 1 m, matching the 1/10th turbine diameter (D) recommended to resolve velocity and turbulence intensity along device wakes. The array layout initially followed recommended staggered configurations with longitudinal and lateral spacings of 10D and 5D, respectively. However, during mean spring tidal conditions, the misalignment of peak flood currents induced significant wake interactions that reduced the array output by about 15% in comparison to peak ebb. These interactions were investigated to adapt array layouts, minimise wake interactions, and optimise the energy conversion. By reducing the lateral spacing between devices to 3D (measured centre to centre rather than tip to tip), the flood ebb asymmetry in energy extraction was lowered from 15% to 2%

Study by DNS of the effects of a shear thickening law on the Taylor-Couette flow

Dans le cadre de nos études sur la réduction de la traînée en conduite par l'emploi d'additifs, nous nous intéressons à l'impact du changement de propriétés sur les instabilités et l'écoulement. Ainsi nous explorons dans ce travail l'impact d'une loi associé à un additif réducteur de traînée sur la naissance et l'évolution des instabilités de Taylor-Couette par simulation numérique directe. Le code SUDRES (Guillou and Makhloufi, 2007) a été modifié pour résoudre les équations de la mécanique des fluides en coordonnées cylindriques

Numerical modelling of hydrodynamics and tidal energy extraction in the Alderney Race: a review

(IF 4.23; Q1)International audienceThe tides are a predictable, renewable, source of energy that if harnessed, can provide significant levels of electricity generation. Alderney Race, with current speeds that exceed 5 m/s during spring tides, is one of the most concentrated regions of tidal energy in the world, with the upper bound resource estimated at 5.1 GW. Due to its significance, the Alderney Race is frequently used for model case studies of tidal energy conversion, and here we review these model applications and outcomes. We examine a range of temporal and spatial modelling scales, from regional models applied to resource assessment and characterisation, to more detailed models that include energy extraction and array optimization. We also examine a range of physical processes that influence the tidal energy resource, including the role of waves and turbulence in tidal energy resource assessment and loadings on turbines. The review discusses model validation, and covers a range of numerical modelling approaches, from 2D to 3D tidal models, two-way coupled wave-tide models, Large Eddy Simulation (LES) models, and the application of optimization techniques. The review contains guidance on model approaches and sources of data that can be used for future studies of the Alderney Race, or translated to other tidal energy regions

Development of a Large-Eddy-Simulation approach with Telemac-3D

Water Qualit