In certain cases, the imported geometries can often contain multiple regions in the computational model with different meshing requirements. For such models, the Region-based sizing method in the ‘Generate the Volume Mesh’ task allows the user to define the cell-size controls for each of the regions independently. In this workshop, we will demonstrate how to create a CFD-ready mesh, using the Ansys Fluent Meshing Watertight Geometry Workflow, that can be used to study the fluid flow through a Catalytic Converter. Apart from understanding the working details of the Region-based sizing method, we will also look at post-volume mesh creation activities like how to rename the zones and extend the outlet boundary, with the intention to avoid backflow during the simulation. Finally, we will understand how to switch to the solution mode, not only using the GUI but also using a TUI command.