An approach to modelling of Active Gurney Flap (AGF) on a helicopter blade involving the application of the FLUENT code with its capabilities enhanced by the Applicant through User Defined Functions (UDFs) is proposed. The Active Gurney Flap will be modelled using UDFs by automatically changing the airfoil or blade section contour and rearranging grid nodes in the zone containing the lower part of the blade. The applied algorithm prohibits harmful distortions of grid cells during AGF operation. The proposed algorithm will be incorporated in the Virtual Rotor (VR) module of UDFs, modelling the kinematics of rotor blades, using the sliding mesh technique available in Fluent, created already and successfully tested by the Applicant. The available in Fluent software models of turbulence and LES/DES schemes will be applied in order to find the most suitable approach for the modeling of AGF on a rotor blade. The two- and three-dimensional flow cases described in the Call for Proposals will be analysed in this work, including 2D and 3D wind tunnel test cases, whirl tower rotor test cases and rotor forward-flight test cases. The VR software and all the UDFs used within this project will be transferred to the Clean Sky Joint Undertaking with documentation, training, and all test cases.