DR_VHAWT (Dual-Rotor Vertical/Horizontal Axis Wind Turbine) is an in-house vortex filament code, developed in FORTRAN 95 by Lee Slew, for the aerodynamic performance prediction of up to two wind turbine rotors operating in either vertical or horizontal axis configuration. Based on the Prandtl’s Lifting-Line theory, this vortex code uses vortex filaments to accurately represent the spatial and temporal variation in the wake behind a wind turbine. The circulation of each vortex filament is evaluated using the Kutta-Joukowski theorem. These vortices are then convected in the flow field using a second-order Adams-Bashforth explicit integration formula. The effect of the wake on the performance of the blades is then calculated based on the Blade Element theory. It should be noted that the code’s ability to accurately predict a wind turbine’s performance greatly depends on the input aerodynamic polars (CL and CD), which can be obtained from either wind tunnel experiments or numerical methods (e.g., XFOIL). For more information, download thesis by Lee Slew, as well as Michael Miller and/or Fereidooni (for more wind turbine research) from our library.