Computational fluid dynamics (CFD) is widely employed for VAWT performance analysis. It
solves the Reynolds Averaged Navier-Stokes equation or the more advanced and costly direct
numerical simulation, large eddy simulation, and detached eddy simulation (DES). Ivan
Dobrev et al. [10] conducted high fidelity simulation to explore the possibility of using the 3-
D Navier-Stokes solver DES solver/k-w model, and particle image velocimetry for
experimental validation. The comparison of wake and shedding vorticity with experiments
shows that the 3-D/k-w modeling gives results were quite similar to phase averaged velocity.
The power coefficient measured was very close to the experiment result, confirming the
capability of DES model to accurately capture the turbulent detached flow. Mohamed [11]
carried out aerodynamic investigation for 20 different airfoils using 2-D unsteady Reynolds
averaged Navier Stokes (RANS) simulation. He found the S-1046 profile for H-Darrieus
rotor very promising for wind energy generation, in particular in urban areas compared to
symmetric airfoils. Many other studies have been done using RANS [12-14]; however, CFD
is computationally intensive as the aerodynamic performance of the turbine is a function of
instantaneous forces and moment coefficient.