PerAWaT - Numerical Modelling of Tidal Turbine Arrays Involving Interactions within an Array: Implementation of the Zero Tangential Shear Condition

Abstract:

The Performance Assessment of Wave and Tidal Array Systems (PerAWaT) project, launched in October 2009 with &pound;8m of ETI investment. The project delivered validated, commercial software tools capable of significantly reducing the levels of uncertainty associated with predicting the energy yield of major wave and tidal stream energy arrays. It also produced information that will help reduce commercial risk of future large scale wave and tidal array developments.<br /><br />This report includes an analysis of numerical modelling of tidal turbine arrays involving interactions within an array. Implementation of the zero tangential shear condition is included.<ul><li>Introduction<ul><li>The Level Set Method</li><li>Ghost Fluid Method</li></ul></li><li>Methodology<ul><li>Calculation of Level Set with re-distancing</li><li>Calculation of slop and curvature and free surface</li><li>Calculation methodology for the Ghost Fluid Method</li></ul></li><li>Implementing unsteady upstream boundary condition</li><li>Implemention<ul><li>A review on previous Connectivity modelling</li><li>A review on previous Re-Distancing modelling</li><li>Current programming strategy</li></ul></li><li>New Modules</li><li>Results</li></ul>The work package objective of WG3 WP2 D2 was to implement a Level-Set free surface model capable of performing a free-surface boundary condition and unsteady upstream boundary condition with Code_Saturne. So far, significant progress has been made to achieve this, but further work is needed on the stratified field approach as a work-around to the obstacles associated with the inaccessibility of the kernel of Code_Saturne. The success of this will be covered in the next deliverable of D3 through verification with experimental data. <br /><br />In the last deliverable D1, cell connectivity and re-distancing were achieved with its success seen in figure 7. The major developments since D1 have been in coding the Gradient Smoothing Method, which is necessary for the calculation of geometric features of the free surface, and coding the GhostFluid Method. The GFM has proven difficult to achieve in view of the lack of advice available to reprogram the kernel of Code Saturne in the way highlighted in section 4.3. The geometrically isotropic, bilinear interpolation scheme employed in the GFM has shown itself to be a stable method. The stratified flow approach will need some care to avoid issues with numerical stability near the interface region of the flow field. To demonstrate the required functionality of the modifications featured in this deliverable, a set of tests is planned as indicated in Figure 11. The results of these tests form the main content of deliverable D3

Publication Year:

2011

Publisher:

ETI

DOI:

https://doi.org/10.5286/ukerc.edc.000333

Author(s):

Ingram, D.M. and Olivieri, D.A.