T2GR (2D hybrid-unstructured grid construction software)

T2GR is a two-dimensional hybrid-unstructured grid construction software, developed by members of the Turbomachines & Fluid Dynamics Laboratory (TurboLab-TUC). The geometry to be examined and the boundaries of the domain are imported in a 2D-coordinates form, through a “.txt” file, or in parametric form, through an “.obj” file. The direction of the nodes must follow counter clockwise sense for external boundary nodes and clockwise sense for internal boundaries. T2GR software enables the creation of purely triangular grids for the simulation of inviscid flows, as well as hybrid unstructured grids, consisting of triangular and quadrilateral elements, in order to accurately solve the boundary layer that develops in the area near the solid walls of the computational domain when simulating viscous flows. For the construction of the triangular grid, the “Delaundo” software developed by J.D. Muller is used, while for the construction of the viscous layers around the solid walls, an algebraic methodology is utilized. An algorithm is applied to suitably combine the triangular and quadrilateral sections into a single grid. All data is stored in properly designed structures. Additionally, a Free-Form Deformation (FFD) tool has been incorporated for the concurrent manipulation of both the geometry and the grid. The software has been implemented in Qt C++ programming language, and is also enriched with a flexible graphical interface (GUI), for easy user interaction, as well as with a viewer for visualizing computational grids based on OpenGL.

References:

S.N. Leloudas, A.I. Eskantar, I.K. Nikolos, "Design of a Low Reynolds Airfoil Family for Small Horizontal Axis Wind Turbine Applications Based on the RG15 Airfoil", Proceedings of the 7th European Conference on Renewable Energy Systems, ECRES 2019, Madrid, Spain, 10-12 June 2019.

A.I. Eskandar, Software development for the generation of two-dimensional hybrid unstructured grids, Diploma Thesis, School of Production Engineering & Management, Technical University of Crete, 10/7/2019.

S.N. Leloudas, A.I. Eskantar, G.N. Lygidakis, I.K. Nikolos, "Low Reynolds Airfoil Family for Small Horizontal Axis Wind Turbines Based on RG15 Airfoil", SN Applied Sciences, 2, 371, 2020. doi.org/10.1007/s42452-020-2161-1.

S.N. Leloudas, G.N. Lygidakis, A.I. Eskantar, I.K. Nikolos, "A Robust Methodology for the Design Optimization of Diffuser Augmented Wind Turbine Shrouds", Renewable Energy, 150, pp. 722-742, 2020. https://doi.org/10.1016/j.renene.2019.12.098

Numerical Applications and Simulations