## 2 Methodology  
### New Omni-Directional Wind-Funnel Design  
The first INVELOX omni-directional wind funnel was introduced by [PERSON] and [PERSON] [8] to harvest wind power by accelerating wind speed at the venturi throat.  
This system works based on capturing wind from all directions and tunnelling it through the convergent-divergent nozzle, where the wind turbine is located at its throat, leading to an increase in wind speed. The detailed dimension and geometry of the first INVELOX were introduced in 2014.  
In this research, a few design parameters are considered, such as the length of each guide vane, number of guide vanes, the elbow diameter, and the ratio of diameter of intake to venturi. Figure 1 includes details of the changes, dimensions, length of guide vane, number of guide vanes, elbow diameter, and the ratio of diameter of intake to venturi to increase the inlet air, reduce the escaping air, avoid the formation of re-circulation zone, increase the pressure drop in the passage, and direct more air to the venturi throat.  
The most prominent changes as compared with the conventional INVELOX are summarized in Table 1.  
The overall wind funnel height was doubled to reduce the amount of air entering the INVELOX and the amount of air escaping from the opposite side of the INVELOX, and thus, increase the pressure drop of the air passage inside.  
Instead of increasing the diameter of the lower funnel like previous research, the lower funnel diameter is fixed at 2 m and extended to the bottom of the funnel at the circular diameter of 7.8 m, giving a narrowing effect on the escaping air path, while the extended length of the guide vane also helps to guide the air towards the venturi throat section and, thus, prevent the early escape of the inlet air flow at the opposite end, directing sufficient speed of the air flow to enter the venturi throat and creating a low-pressure region at the  
Figure 1: **(a)** Schematic drawing of the omni-directional wind funnel; (b) detailed dimension and geometry of the omni-directional wind funnel; (c) 3D model of the omni-directional wind funnel with the configuration of five fins at 72\({}^{\circ}\) each; (d) cross section of the 3D model.  
venturi. Meanwhile, the extended length of lower-funnel diameter and guide vane could also prevent the formation of recirculation zone in the passage, which is undesirable and would reduce the amount of air to the venturi throat.  
In addition, the reduction in the size of the venturi throat and elbow diameter by 8.6% and 11.4%, respectively, as compared with the conventional INVELOX, has created the contraction effect at the venturi throat and, thus, increased the trapped air speed to satisfy the law of mass conversion. This could also increase the overall pressure drop of the wind funnel.  
Finally, the upper diameter is also doubled, while the inlet height is increased by 28%, as compared with the conventional INVELOX, to increase the amount of the inlet air to overcome the pressure drop effect, which limits the amount of air entering the wind funnel. The configuration of five fins at 72\({}^{\circ}\) each, compared with the four fins in the conventional configuration, aims to collect and direct the winds from all directions more efficiently. Figure 1b shows the best design.