This lesson covers the process of defining the domain of a boundary value problem using Ansys software. The lesson begins with the creation of a fluid region surrounding a cylinder using the Ansys Workbench™ simulation integration platform. The lesson explains how to rename the project for better organization, change the analysis type to 2D, and open Ansys Discovery™ 3D product simulation software. The lesson also covers how to set the units and display precision, sketch on the correct plane. Finally, the lesson concludes with how to set up locations for applying boundary conditions using name selections and save the project.