This chapter describes Fluent’s Virtual Blade Model (VBM) which is used for analyzing the aerodynamic interaction between multiple rotors and airframes. With this technique, the 3D rotors are replaced with actuator disks that introduce the effect of the rotors via implicit momentum source terms in the governing equations. Since the actual blades are not physically modeled, the technique is hence referred to as the Virtual Blade Model. The model supports hybrid unstructured meshes for easy handling of multiple rotor geometries in close proximity, with convenient local mesh clustering. The non-linear aerodynamic interaction of rotor wakes with each other and with other structural components is obtained by coupling the VBM with Fluent’s Navier-Stokes solver. In addition, when using the VBM, rotor trimming can be performed at desired thrust and moments in an automatic and robust fashion using an iterative method to account for the non-linear relation between blade pitch and rotor performance. A propeller and a well-studied simplified single rotor helicopter model in forward flight are presented in as tutorials to show the capabilities of Fluent VBM. See Fluent’s Virtual Blade Model Tutorials for more details.