Vertical axis wind turbines (VAWTs) have regained attention for distributed, urban, and floating offshore applications, yet the literature remains fragmented across competing rotor concepts and modelling traditions. This review consolidates the principal archetypes—Savonius, H-Darrieus, troposkein Darrieus, helical Darrieus, and Savonius–Darrieus hybrids—through five governing parameters: drag-versus-lift-driven operating principle, tip speed ratio $\mathsf{\lambda }=\mathsf{\omega }\mathrm{R}/{\mathrm{V}}_{\infty }$ (0.6–1.2 for Savonius; 2.5–5.0 for Darrieus), solidity $\mathsf{\sigma }=\mathrm{N}\mathrm{c}/\mathrm{R}$ (0.1–0.4), chord-based Reynolds number ${\mathrm{R}}_{\mathrm{e}\_\mathrm{c}}$ (${10}^5–{10}^6$), and peak power coefficient ${\mathrm{C}}_{\mathrm{p}\_\mathrm{m}\mathrm{a}\mathrm{x}}$ (0.15–0.25 for Savonius; 0.35–0.45 for optimized H-Darrieus). Off-design performance is dominated by unsteady mechanisms that quasi-steady streamtube models cannot resolve—leading edge vortex shedding, dynamic stall hysteresis, blade–wake interaction, and flow-curvature-induced virtual camber—each examined for its contribution to the instantaneous torque ${\mathrm{C}}_{\mathrm{T}}\left(\mathsf{\theta }\right)$ and the cycle-averaged ${\mathrm{C}}_{\mathrm{p}}$. Turbulence closures are benchmarked against phase-locked PIV and torque measurements: $\mathrm{k}–\mathsf{\omega }\mathrm{S}\mathrm{S}\mathrm{T}$ URANS captures peak-region ${\mathrm{C}}_{\mathrm{p}}$ to within $\pm 5–10\%$ but over-predicts torque below ${\mathsf{\lambda }}_{\mathrm{o}\mathrm{p}\mathrm{t}}$; the $\mathsf{\gamma }–{\mathrm{R}}_{\mathrm{e}\_\mathsf{\theta }}$ transition SST model reduces this error to $\pm 3–5\%$; DES, DDES, and LES reach $\pm 2–3\%$ at one to two orders of magnitude higher cost. Best practice computational fluid dynamics (CFD) guidelines are consolidated: domain extents of 15D upstream, 10D downstream, and 20D lateral; rotating sub-domain ${\mathrm{D}}_{\mathrm{r}\mathrm{o}\mathrm{t}}$ $\approx 1.5\mathrm{D}$; ${\mathrm{y}}^{+}\le 1$; $\Delta \mathsf{\theta }\le 0.1°$; and 20–30 revolutions before sampling. Performance enhancement strategies (variable pitch, guide vanes, helical twist, and hybridization) are reviewed quantitatively, with reported ${\mathrm{C}}_{\mathrm{p}}$ gains of $5–30\%$. Four research priorities are identified: (i) transition-sensitive turbulence closures validated below ${\mathrm{R}}_{\mathrm{e}\_\mathrm{c}}$ = $5\times {10}^5$; (ii) coupled aero-hydro-servo-elastic models for floating offshore VAWTs; (iii) machine-learning-augmented turbulence modelling—including physics-informed neural networks (PINNs) and neural-network-corrected RANS closures—to improve unsteady flow prediction at sub-LES cost; and (iv) integrated aeroacoustic–aeroelastic frameworks for urban and building-integrated deployment.

This research aimed to quantitatively investigate the impact of a novel approach, known as the undulatory form inspired by the flower of life concept, on the performance of conventional Savonius Wind Turbine (SWT). This approach entails the replacement of the conventional SWT's concave surface with a series of small blades, distributed in both convex and concave positions, arranged in an undulating pattern along the surface. Four models have been tested (MODEL22, MODEL30, MODEL60 and MODEL80) in an attempt to verify the effectiveness of this new method in enhancing wind turbine power coefficient. We use ANSYS Fluent software to solve the Unsteady Reynolds-Averaged Navier-Stokes (URANS) and the SST k-omega turbulence model equations. The experimental and numerical data supported the innovative methodology, which was meant to show how it could increase the wind turbine's power coefficient in a tip speed ratio (TSR) range of 0.5 to 1.2 while keeping a 15% overlap ratio (OR) relative to the rotor diameter and an inlet velocity of 7 m/s with a R_e=4.43×〖10〗^5. We conducted a comparison between our innovative model and the experimental and numerical studies and found that the undulatory shape significantly improved the power coefficient. MODEL60 was the optimal model, showing an improvement of 17.34% at TSR = 0.7 compared to a wavy-form numerical study and 6.25% at TSR = 1 compared to the experimental study.

Journal sscm, jsscm, journal of the serbia society for computational mechanics, mechanics, serbia mechanics, journal

The effect of rotation rate parameter, cylinder diameter, and the variation of Reynolds number on the circular cylinder was the main object of this 2D numerical study. Rotating and stationary circular cylinder in steady and unsteady incompressible flow has been analysed. For each value of Reynolds number, we have varied the rotation rate parameter clockwise and anti-clockwise to visualize their effect on the drag, lift, and coefficients. All cases have carried out steady laminar, unsteady laminar, and turbulent regimes. A realizable K-epsilon model has been used to solve the Navier Stokes equations for the turbulent regime. Results were in good agreement with the recent findings.

Journal sscm, jsscm, journal of the serbia society for computational mechanics, mechanics, serbia mechanics, journal