*2.1. Geometries*

The geometry was generated using an ANSYS Design Modeler, commercial software, which is included in the ANSYS WorkBench package. A parametric study was performed for the study. The geometries of the tunnel and the variables considered are given in Figure 3. Face-to-duct end distances were large enough to ensure that the flow was not influenced by boundary conditions. The tunnel profile was defined for a regular tunnel section. All of the analyzed profiles were concentric to that depicted in Figure 3. Common sections for mine ducts were retrieved from commercial catalogs and particularly from [22] (p. 236). The parametrized geometry is specified in Table 1 for the four scenarios considered.

**Figure 3.** Definition of the parameters. Tunnel view: Left, lateral; right, front.


**Table 1.** Geometrical parameters used for the parametric study.
