gmsh script for generating 2D/3D mesh for straight pipe

• For nomenclature and the mesh parameters, see the attached figure
• Choose either 2D (= circular disc) or 3D (= straight pipe) mesh options in GENERAL SETTING
• Set the mesh controlling parameters in SETTINGS
• To generate 3D mesh: gmsh pipeMesh.geo -3 -order 2
• To generate 2D mesh: gmsh pipeMesh.geo -2 -order 2
• For turbulent pipe flow simulation using Nek5000, see this technical report.