BSC collaborates with Iberdrola (https://www.iberdrola.es) on wind resource assessment. As part of this collaboration, the CFD version of code ALYA (https://www.bsc.es/es/computer-applications/alya-system) developed at BSC has been adapted so that Iberdrola can use it as an alternative to commercial software for wind farm assessment. This has several advantages. The wind farm assessment tool is based on ALYAlya, a code designed to run efficiently on supercomputers comprising many . Therefore, thousands of processors, which in turn permits can be used to simulate onsimulations using significantly finer meshes than those possible with a commercial code. can handle.FurthermoreOn the other hand, since BSC is the developer of ALYAlya, new models can rapidly be implemented and tested. RANS turbulence models are the standard approach for wind farm assessment but recently LES models are also being consideredtested since they can become feasible with the advent of Exascale computers. With the help of HPC experts from the Energy Oriented Center of Excellence (EoCoE) experts the code has been optimized to increase its node level performance. Computational savingsReductions of up to 38% have been obtained in the assembly of the matrix for the Navier Stokes equations. Moreover, we are working withelinear algebrasolverspecialistsexperts from EoCoE to test 2 iterative solvers (Maphys and AGMG). For some LES cases, we have seen CPU time reductions of more than 50% in the solver CPU time with AGMG.
In order to make the tools easy to handle by wind assessment engineers a series of pre-process and post-process tools tailored to their needs have been developed. The process starts with the creation of a mesh in a highly automated way. The key inputs the user specifies needs to give are the extent of the domain he wants to simulate together withand topography and roughness files in any of the standard formats (grd, map, etc). Further,Sseveral coordinate systems can be used (WGS_84,NAD_83,ED_50, …). Moreover, the user can easily modify the size of the meshes to be used. The meshing process has recently been enhanced with the possibility of including adaptive refinement to take into account the wind turbines and their wakes [GP15]. This,In combinationtogether with an actuator disc model, this allows simulating the wind deficit generated by the wind turbines to be taken into account directly. The second step is the generation of boundary conditions and input files for ALYAlya. This is done with minimal input from the user. This ends the pre-processing phase, after which and now ALYAlya can be run in thousands of processors for.sSeveral different wind directions. are simulated. A post-processing tool has been developed that allows blending the results from the simulations with experimental data at a mast. In this way, the information at the mast is extrapolated to the whole domain of interest to help select of the optimal position for the wind turbines. The output from the post processing step is a resource grid file (WRG) with Weibull values A and k over the whole domain that can easily be used in the standard workflow for wind farm assessment.
[GP15] A. Gargallo-Peiró, M. Ávila, H. Owen, L. Prieto, A. Folch. Mesh generation for Atmospheric Boundary Layer simulation in wind farm design and management, 24th International Meshing Roundtable (IMR24).