Wind Energy Potential Ranking of Meteorological Stations of Iran and Its Energy Extraction by Piezoelectric Element

: Piezoelectrics have been used in several recent works to extract energy from the environment. This study examines the average wind speed across Iran and evaluates the amount of extracted voltage from vortex-induced vibrations with the piezoelectric cantilever beam (Euler–Bernoulli beam). This study aims to compute the maximum extracted voltage from polyvinylidene ﬂuoride piezoelectric cantilever beam at the resonance from vortex-induced vibration to supply wireless network sensors, self-powered systems, and actuators. This simulation is proposed for the ﬁrst-ranked meteorological station at its mean velocity over six years (2015–2020), and the ﬁnite element method is used for this numerical computation. The wind data of 76 meteorological stations in Iran over the mentioned period at the elevation of 10 m are collected every three hours and analyzed. Based on the statistical data, it is indicated that Zabol, Siri Island, and Aligudarz stations had recorded the maximum mean wind speed over the period at 6.42, 4.73, and 4.42 m/s, respectively, and then energy harvesting at the mean wind speed of top-ranked station (Zabol) is simulated. The prevailing wind directions are also studied with WRPLOT view software, and the wind vector ﬁeld of 15 top-ranked stations is plotted. For energy harvesting simulation, periodic vortex shedding behind the bluff body, known as vortex-induced vibration, is considered numerically (ﬁnite element method). The piezoelectric cantilever beam is at a millimeter-scale and has a natural frequency of 630 Hz in its mode shapes to experience resonance phenomenon, which leads to maximum extracted voltage. The maximum extracted voltages for three piezoelectric cantilever beams with the natural frequency of 630 Hz with the wind speed of 6 m/s are 1.17, 1.52, and 0.043 mV, which are suitable for remote sensing, supplying self-power electronic devices, wireless networks, actuators, charging batteries, and setting up smart homes or cities. To achieve this, several energy harvesters with various dimensions should be placed in different orientations to utilize most of the blown wind.


Introduction
The energy crisis, air pollution, increasing energy demand, and global warming have motivated various communities to shift to renewable energy sources such as wind, solar, wave, and geothermal energy. Global energy demand is predicted to increase 25% by 2040. Renewable energy sources, nuclear energy, and natural gas will meet most of this energy demand [1]. Energy production from wind resources is proper because of its characteristics such as sustainability, high potential, and predictability [2]. The extraction of energy by wind farms has almost doubled from 2014 to 2018 [3]. Wind energy resources the experimental and numerical energy harvesting from turbulent flow in a channel with piezoelectric matter. The vortex generator plate, made up of conical nozzles, was used to increase the amount of electricity generated. They discovered that the best Reynolds number for extracting energy is about 30,000. Cha et al. [23] explored the possibility of extracting energy from fishtail vibration with piezoelectric materials (MFC piezoelectric sealed with epoxy) to drive fish tags. In this research, fluid-solid interaction (FSI) was described. In a study, Lai et al. [23] investigated harvesting energy from a low-speed wind regime with a novel hybrid energy conversion system. A piezoelectric layer made the conversion system with a dielectric generator inside a cylinder. VIV caused vibration in the beam, and piezoelectric directly converted this vibration into electricity. The dielectric was mounted in the cylinder, which could move normally in the flow direction and produce electricity. Li et al. [24] proposed an energy harvester structure based on a galloping piezoelectric-electromagnetic. In this structure, a vibration of the piezoelectric beam caused a vibration in the magnets, and electromagnetic energy could be captured. They have found that at a wind speed of 9 m/s, the effective output power is 121% more than the classic galloping piezoelectric with no magnet. The results from the numerical simulation were finally verified experimentally, which had a good agreement with the results derived from the simulation. Song et al. [25] have investigated tandem piezoelectric energy harvesters from water flow. In this study, mathematic models were coupled with hydrodynamics forces obtained from the computational fluid dynamics. They have found that, in a highspeed flow regime, a piezoelectric beam placed downstream performs better due to vortexinduced vibration. The maximum extracted power from the downstream piezoelectric harvester was 371 µW, which was approximately 2.5 times the amount extracted from the upstream harvester. Zhao et al. [26] have studied energy harvesting based on transverse galloping for wireless sensing power supply. They have also compared the single degree of freedom model (SDOF) with single-mode and multi-mode Euler-Bernoulli distributed parameters and then validated with the experimental model, which had a rough agreement with distributed parameters. A non-linear bi-directional piezoelectric energy harvester with vortex-induced vibration was developed and analyzed by Su and Wang [27]. In this model, the Euler-Bernoulli piezoelectric cantilever beam was fabricated and experimentally tested in a wind tunnel. They have found that the prototype has extreme non-linearity in a horizontal direction. With the added magnet, the structure greatly enhanced the lock-in region.
Wind energy conversion systems (WECS) impact factors are mean wind speed and prevailing wind direction [28]; the wind data of 76 meteorological stations in Iran is collected every three hours and analyzed in this study. Therefore, this study examines the average wind speed over Iran and evaluates the amount of extracted voltage from vortexinduced vibrations, with the piezoelectric cantilever beam (Euler-Bernoulli beam). This study aims to compute the maximum extracted voltage from PVDF piezoelectric cantilever beam at the resonance from VIV, to supply wireless network sensors, self-powered systems, and actuators. This simulation is proposed for the first-ranked meteorological station (Zabol station) at its mean velocity over the mentioned period, and the finite element method is used for this numerical computation.

Data Collection and Stations Description
Iran has a 1.6 million m 2 area with different climates and is located in Central Asia and the Northern Hemisphere. The Alborz and Zagros Mountains ranges in Iran's north, west, and southwest is mountainous. Iran's central and eastern regions are deserts. The Persian Gulf and the Gulf of Oman are the southern edges of Iran. In addition to the mountain range, there is the coastal area of the Caspian Sea in the north. It depicts weather and climate variations in every part of Iran, allowing summer and winter to be felt simultaneously in different areas of the country [29].
Meteorological data of 76 synoptic stations across Iran, including coastal, desert, and mountainous areas, were collected from Iran's meteorological organization (IRIMO) over six years (1 August 2015 to 1 July 2020). Iran is an ideal case for studying wind energy potential and its variability. Iran has a complex and diverse topography (including mountains, plateaus, plains, hills, and basins), and climate conditions (e.g., arid, semiarid, Mediterranean, and humid climate zones) [30,31]. Figure 1 illustrates 76 synoptic stations across Iran. tain range, there is the coastal area of the Caspian Sea in the north. It depicts weather and climate variations in every part of Iran, allowing summer and winter to be felt simultaneously in different areas of the country [29].
Meteorological data of 76 synoptic stations across Iran, including coastal, desert, and mountainous areas, were collected from Iran's meteorological organization (IRIMO) over six years (1 August 2015 to 1 July 2020). Iran is an ideal case for studying wind energy potential and its variability. Iran has a complex and diverse topography (including mountains, plateaus, plains, hills, and basins), and climate conditions (e.g., arid, semiarid, Mediterranean, and humid climate zones) [30,31]. Figure 1 illustrates 76 synoptic stations across Iran. Wind speed and direction, humidity, and temperature are all determined by synoptic data. In this analysis, only wind data is taken into account. Wind data are analyzed with WRPLOT view software (Ver. 8.0.2). Table S1 lists each station's geographical characteristics and wind indicators, such as the prevailing wind direction, mean wind speed, and maximum speed. Each station's windrose plot was examined to determine the prevailing wind direction. The average wind speed in these stations ranges from 1.35 to 6.42 m/s in Dogonbadan (Kohgiluyeh and Boyer province) and Zabol (Sistan and Balouchestan province), respectively. Wind speed and direction, humidity, and temperature are all determined by synoptic data. In this analysis, only wind data is taken into account. Wind data are analyzed with WRPLOT view software (Ver. 8.0.2). Table S1 lists each station's geographical characteristics and wind indicators, such as the prevailing wind direction, mean wind speed, and maximum speed. Each station's windrose plot was examined to determine the prevailing wind direction. The average wind speed in these stations ranges from 1.35 to 6.42 m/s in Dogonbadan (Kohgiluyeh and Boyer province) and Zabol (Sistan and Balouchestan province), respectively.

Simulation Procedure
By placing an object in the moving fluid, vortices appear behind it. These vortices shed at the wake periodically and exert an external periodic pressure difference to the body  (1) and (2).
In these Equations, ρ is the air density (kg/m 3 ), V is wind speed (m/s), D is diameter of the bluff body (m), µ is dynamic viscosity of the air (Pa·s), and f is the vortex shedding frequency (Hz). The shedding from a circular cross-sectioned cylinder occurs when the Reynolds number is in the range of 10 2 -10 7 , and the Strouhal number approximately is 0.21 [32].
The extraction of energy from vibrations induced by wind flow vortices with piezoelectric material is simulated in this research. The wind flow passes through the circular bluff body, exerting lift force on the cantilever piezoelectric beam periodically (due to the pressure difference). This force causes polarization and vibration in the piezoelectric.
Vibration equation of beam can be expressed as Equation (3), in which y, . y, and ..
y are displacement, velocity, and acceleration, C is mechanical damping, and k is stiffness.
As mentioned, external force that is exerted at the beam is lift force and also expressed in Equation (4), where A 0 is projected area and C L is coefficient of lift force.
Motion equation of VIV can be obtained from Equation (5), where ω 0 is natural frequency and ζ is damping ratio. ..
Strain in piezoelectric beam can be obtained from Equation (6), in which u b is the amplitude of piezoelectric beam. By integration of potential Vector D, Piezoelectric charge Q can be obtained in which D and Q are expressed by Equations (6) and (7), where d 31 is piezoelectric constant, E b is Young's modulus of the piezoelectric cantilever, w (m) is thickness, and L (m) is the length of piezoelectric.
At last, voltage polarization of piezoelectric can be obtained from Equation (9).
In Equation (9), C b (V/C) is capacitance of piezoelectric.

Energy Harvesting Simulation
Drag force had no impact because of the PEH structure, thus it was neglected. The lift force acting on the piezoelectric cantilever beam due to wind flow passing through the bluff body was measured (per length). Wind speed ranged from 1 to 6 m/s. The highest average wind speed in this timeframe was about 6 m/s, according to 6-year synoptic data from 76 meteorological stations. Since the maximum lift force is exerted at maximum velocity, a simulation based on a wind speed of 6 m/s is proposed. A schematic of the PEH structure is shown in Figure 2. The flow field is considered as a rectangular channel with a length and width of 100 and 20 mm, respectively. The oscillator cantilever piezoelectric beam is 15 mm away from the circular bluff body, which is fixed and has a diameter of 2 mm.
EER REVIEW 6 beam is 15 mm away from the circular bluff body, which is fixed and has a diameter of 2 mm. According to the specificity of the bluff body diameter, wind speed, and other required parameters, the Reynolds number is about 800. The Strouhal number can also be considered equal to 0.21, which ultimately has a vortex shedding frequency of 630 Hz.
The resonance phenomenon will occur if the vortex shedding frequency equals the piezoelectric beam's normal frequency. The maximum deflection of the piezoelectric beam occurs when the resonance happens, and the highest voltage can be obtained from the piezoelectric beam. At resonance phenomenon, due to oscillations and high displacement of the piezoelectric beam, conventional piezoceramics cannot be used due to fragility, and flexible piezoelectrics such as PVDF or MFC should be used. This study uses PVDF piezoelectric; its characteristic parameter is listed in Table 1.

Parameters
Value As the vortex shedding frequency is known, three piezoelectric beams are selected by trial-and-error approach and eigenfrequency study simulation. These three PVDF beams with different dimensions have a natural frequency of about 630 Hz (at mode shapes), which at the wind velocity of 6 m/s leads to a resonance phenomenon. The following three specifications in Table 2 demonstrate piezoelectric beam dimensions.  According to the specificity of the bluff body diameter, wind speed, and other required parameters, the Reynolds number is about 800. The Strouhal number can also be considered equal to 0.21, which ultimately has a vortex shedding frequency of 630 Hz.
The resonance phenomenon will occur if the vortex shedding frequency equals the piezoelectric beam's normal frequency. The maximum deflection of the piezoelectric beam occurs when the resonance happens, and the highest voltage can be obtained from the piezoelectric beam. At resonance phenomenon, due to oscillations and high displacement of the piezoelectric beam, conventional piezoceramics cannot be used due to fragility, and flexible piezoelectrics such as PVDF or MFC should be used. This study uses PVDF piezoelectric; its characteristic parameter is listed in Table 1. As the vortex shedding frequency is known, three piezoelectric beams are selected by trial-and-error approach and eigenfrequency study simulation. These three PVDF beams with different dimensions have a natural frequency of about 630 Hz (at mode shapes), which at the wind velocity of 6 m/s leads to a resonance phenomenon. The following three specifications in Table 2 demonstrate piezoelectric beam dimensions. The lift force (per length) in the wind velocity range of 1 to 6 m/s is numerically simulated. The maximum lift force (6 m/s wind velocity) is applied with a frequency domain in the range of 625 to 635 Hz with the step of 0.01. Coupled electrostatic and electrical circuit modules with a resistor of 10 9 Ω are used to simulate the output voltage at the resonance for energy extraction. The energy harvesting simulation flowchart is presented in Figure 3.
FOR PEER REVIEW 7 resonance for energy extraction. The energy harvesting simulation flowchart is presented in Figure 3.

Results and Discussion
Table S1 is ranked according to the average wind speed for energy harvesting. Zabol city, Siri Island, and Aligudarz city have the highest average speeds, and their topography is desert, marine, and mountainous, respectively. Each of these three cities is discussed in greater depth in the following sections. The wind vector field for the first 15 stations is shown in Figure 4. The predominant winds of the south of Iran, the Persian Gulf, and the Omen Sea are all oriented west (Figure 4). The most significant wind vector in Iran is guided northwest for Zabol station. The central part of Iran is not among the top 15 stations with the fastest mean wind speed, which may be due to the country's civilization in this area. According to meteorological data of Birjand, Sabzevar, and Quchan cities, the prevailing wind direction is toward the east.

Results and Discussion
Table S1 is ranked according to the average wind speed for energy harvesting. Zabol city, Siri Island, and Aligudarz city have the highest average speeds, and their topography is desert, marine, and mountainous, respectively. Each of these three cities is discussed in greater depth in the following sections. The wind vector field for the first 15 stations is shown in Figure 4. The predominant winds of the south of Iran, the Persian Gulf, and the Omen Sea are all oriented west (Figure 4). The most significant wind vector in Iran is guided northwest for Zabol station. The central part of Iran is not among the top 15 stations with the fastest mean wind speed, which may be due to the country's civilization in this area. According to meteorological data of Birjand, Sabzevar, and Quchan cities, the prevailing wind direction is toward the east.

Zabol
Zabol city is located in the northwestern part of Sistan and Balouchestan. Winds of over 200 km per hour blow through Zabol city, which has a desert topography. According to the meteorological data from the synoptic station throughout the period, the average wind speed in this station was 6.42 m/s. The prevailing wind direction is northwest, according to the windrose diagram of this station ( Figure 5).
The resultant vector is shown in windrose diagrams. The resultant vector combines the frequency of winds in each direction to get an average wind direction. In the calculation of the resultant vector, wind speed has no role. For the Zabol station, the resultant vector is in the same direction as the prevailing wind direction. The frequency distribution of different wind classes ( Figure 6) indicates that the recorded speed of 45% of the blown winds is between 1 and 4 m/s, and about 50% has a speed between 4 and 15 m/s, which is significant.

Zabol
Zabol city is located in the northwestern part of Sistan and Balouchestan. Winds of over 200 km per hour blow through Zabol city, which has a desert topography. According to the meteorological data from the synoptic station throughout the period, the average wind speed in this station was 6.42 m/s. The prevailing wind direction is northwest, according to the windrose diagram of this station ( Figure 5).
The resultant vector is shown in windrose diagrams. The resultant vector combines the frequency of winds in each direction to get an average wind direction. In the calculation of the resultant vector, wind speed has no role. For the Zabol station, the resultant vector is in the same direction as the prevailing wind direction. The frequency distribution of different wind classes ( Figure 6) indicates that the recorded speed of 45% of the blown winds is between 1 and 4 m/s, and about 50% has a speed between 4 and 15 m/s, which is significant.

Siri Island
Siri Island is located in the southern part of Iran in Hormozgan province and is considered a coastal location. According to the meteorological data of the synoptic station, the average wind speed over the mentioned period was 4.73 m/s (Table S1). Based on the windrose diagram (Figure 7), approximately 33% of the prevailing winds have been

Siri Island
Siri Island is located in the southern part of Iran in Hormozgan province and is considered a coastal location. According to the meteorological data of the synoptic station, the average wind speed over the mentioned period was 4.73 m/s (Table S1). Based on the windrose diagram (Figure 7), approximately 33% of the prevailing winds have been

Siri Island
Siri Island is located in the southern part of Iran in Hormozgan province and is considered a coastal location. According to the meteorological data of the synoptic station, the average wind speed over the mentioned period was 4.73 m/s (Table S1). Based on the windrose diagram (Figure 7), approximately 33% of the prevailing winds have been blown from west and southwest, 30% from east and northeast. The resultant vector determines the direction to the northwest.  The frequency distribution of different wind classes is shown in Figure 8. According to that, more than 90% of prevailing winds of Siri Island have a speed between 1 and 15 m/s, and about 50% of this recorded data is between 4 and 15 m/s, which plays a key role in energy conversion systems. The highest wind speed of the region in the period is reported to be 42 m/s. The frequency distribution of different wind classes is shown in Figure 8. According to that, more than 90% of prevailing winds of Siri Island have a speed between 1 and 15 m/s, and about 50% of this recorded data is between 4 and 15 m/s, which plays a key role in energy conversion systems. The highest wind speed of the region in the period is reported to be 42 m/s.  The frequency distribution of different wind classes is shown in Figure 8. According to that, more than 90% of prevailing winds of Siri Island have a speed between 1 and 15 m/s, and about 50% of this recorded data is between 4 and 15 m/s, which plays a key role in energy conversion systems. The highest wind speed of the region in the period is reported to be 42 m/s.

Aligudarz
Aligudarz meteorological station is in a mountainous region located in the western part of Iran. The average wind speed in this region from August 2015 to July 2020 is

Aligudarz
Aligudarz meteorological station is in a mountainous region located in the western part of Iran. The average wind speed in this region from August 2015 to July 2020 is 4.42 m/s. According to the windrose diagram (Figure 9), 35% of the wind in this area blows from the southeast. The resultant vector is also towards the southeast. The frequency distribution of different wind classes is in Figure 10, which demonstrates that 48% of the winds have a speed between 1 and 4 m/s, and approximately 43% have a speed between 4 and 15 m/s. The highest reported wind speed in this meteorological station is 64 m/s.

Lift Force
The maximum amount of the lift force at each velocity is presented in Table 3. The lift force is proportional to the square of the velocity, therefore:

Lift Force
The maximum amount of the lift force at each velocity is presented in Table 3. The lift force is proportional to the square of the velocity, therefore: The R 2 value of the curve fitting to the maximum points of lift force was equivalent to 0.996, which is very close to 1 when a parabolic curve was fitted to the maximum points of lift force at each velocity. This implies that the simulation of the lift force at each velocity is a function of the parabolic curve ( Figure 11).

Lift Force
The maximum amount of the lift force at each velocity is presented in Table 3. The lift force is proportional to the square of the velocity, therefore: The R 2 value of the curve fitting to the maximum points of lift force was equivalent to 0.996, which is very close to 1 when a parabolic curve was fitted to the maximum points of lift force at each velocity. This implies that the simulation of the lift force at each velocity is a function of the parabolic curve ( Figure 11).

Simulation Based on Piezoelectric Beam I
The natural frequency of the piezoelectric beam, which is 18.5 mm long and 1.0016 mm thick, is about 630 Hz in its first mode shape. This frequency is close to the vortex shedding frequency in the wind flow passage at a speed of 6 m/s through the bluff body with the specified diameter. The deformation of this cantilever beam is shown in Figure 12. As can be observed from Figure 13, the resonance happened at the frequency of around 630 Hz, and the maximum voltage of 1.17 mV has extracted from the first mode shape.

Simulation Based on Piezoelectric Beam I
The natural frequency of the piezoelectric beam, which is 18.5 mm long and 1.0016 mm thick, is about 630 Hz in its first mode shape. This frequency is close to the vortex shedding frequency in the wind flow passage at a speed of 6 m/s through the bluff body with the specified diameter. The deformation of this cantilever beam is shown in Figure  12. As can be observed from Figure 13, the resonance happened at the frequency of around 630 Hz, and the maximum voltage of 1.17 mV has extracted from the first mode shape.

Simulation Based on Piezoelectric Beam II
The second piezoelectric beam, 46 mm long and 0.99 mm thick, experiences a resonance phenomenon at the second mode shape (Figure 14). The output voltage at the frequency of 630 Hz is equal to 1.52 mV. Figure 15 shows the output voltage versus frequency for this beam.

Simulation Based on Piezoelectric Beam II
The second piezoelectric beam, 46 mm long and 0.99 mm thick, experiences a resonance phenomenon at the second mode shape (Figure 14). The output voltage at the frequency of 630 Hz is equal to 1.52 mV. Figure 15 shows the output voltage versus frequency for this beam.

Simulation Based on Piezoelectric Beam II
The second piezoelectric beam, 46 mm long and 0.99 mm thick, experiences a resonance phenomenon at the second mode shape ( Figure 14). The output voltage at the frequency of 630 Hz is equal to 1.52 mV. Figure 15 shows the output voltage versus frequency for this beam.

Simulation Based on Piezoelectric Beam III
The third piezoelectric beam, with a length of 55 mm and a thickness of 0.5053 mm, in its third mode shape has a frequency equal to 630 Hz, in which resonance phenomena occur in the third mode shape (Figure 16). The maximum output voltage is equal to 0.043 mV. Figure 17 shows the output voltage versus frequency. Figure 15. Output voltage from piezoelectric beam II at second mode shape.

Simulation Based on Piezoelectric Beam III
The third piezoelectric beam, with a length of 55 mm and a thickness of 0.5053 mm, in its third mode shape has a frequency equal to 630 Hz, in which resonance phenomena occur in the third mode shape (Figure 16). The maximum output voltage is equal to 0.043 mV. Figure 17 shows the output voltage versus frequency.

Conclusions
The proportion of renewable energy in a community's energy supply is steadily growing. Wind energy has been highly regarded among various renewable energy sources due to its high capacity, ease of conversion, and predictability and has thus made considerable progress over the years. The use of non-rotating turbines such as vortex bladeless wind turbines [33] and Invelox [34] is one of the latest advances in wind energy extraction. Piezoelectric materials have also been widely investigated due to their simplicity of operation and the possibility of using them in low-power or self-actuating sensors and electronic devices. Therefore, in this study, wind data of 76 meteorological stations in

Simulation Based on Piezoelectric Beam III
The third piezoelectric beam, with a length of 55 mm and a thickness of 0.5053 mm, in its third mode shape has a frequency equal to 630 Hz, in which resonance phenomena occur in the third mode shape (Figure 16). The maximum output voltage is equal to 0.043 mV. Figure 17 shows the output voltage versus frequency.

Conclusions
The proportion of renewable energy in a community's energy supply is steadily growing. Wind energy has been highly regarded among various renewable energy sources due to its high capacity, ease of conversion, and predictability and has thus made considerable progress over the years. The use of non-rotating turbines such as vortex bladeless wind turbines [33] and Invelox [34] is one of the latest advances in wind energy extraction. Piezoelectric materials have also been widely investigated due to their simplicity of operation and the possibility of using them in low-power or self-actuating sensors and electronic devices. Therefore, in this study, wind data of 76 meteorological stations in Figure 17. Output voltage from piezoelectric beam III at third mode shape.

Conclusions
The proportion of renewable energy in a community's energy supply is steadily growing. Wind energy has been highly regarded among various renewable energy sources due to its high capacity, ease of conversion, and predictability and has thus made considerable progress over the years. The use of non-rotating turbines such as vortex bladeless wind turbines [33] and Invelox [34] is one of the latest advances in wind energy extraction. Piezoelectric materials have also been widely investigated due to their simplicity of operation and the possibility of using them in low-power or self-actuating sensors and electronic devices. Therefore, in this study, wind data of 76 meteorological stations in Iran over six years (2015-2020) were collected every three hours, and the average speed and direction of the prevailing winds of each were examined. Three meteorological stations in Zabol with 6 m/s, Aligudarz 4.5 m/s, and Siri 4 m/s had the highest average of wind speeds in this period. Zabol, Aligudarz, and Siri Island stations prevailing wind directions are northwest, southwest, and west, respectively. Winds are toward the west for the southern part of Iran (the Persian Gulf and Oman Sea).
Considering the maximum average speed, known bluff body's diameter, and the Strouhal number (approximately 0.21), the frequency of vortex shedding is about 630 Hz. By selecting three elements of PVDF piezoelectric cantilever with different sizes and a natural frequency of 630 Hz, the voltage extracted when the resonance phenomenon occurs is as follows: • The maximum voltage of 1.17 mV has been harvested from the piezoelectric element with dimensions of 18.5 × 1.0016 mm. • From the second piezoelectric element with 46 × 0.99021 mm dimensions, which has a natural frequency of 630 Hz at its second mode, a voltage of 1.52 mV was extracted.

•
The third element with dimensions of 55 × 0.5503 mm, which has a natural frequency of 630 Hz in its third shape mode, can also pick up the maximum voltage of 0.043 mV during amplification.
The amount of voltage obtained is also low due to the energy harvester's small size; therefore, multiple elements of various sizes and orientations can be positioned at a distance of 20 times the length of each other to neutralize each other's effect due to wind cycling and to increase harvested energy. This study shows that energy harvesting from vortex-induced vibration can supply wireless sensors and self-powered systems for developing smart cities and houses.

Conflicts of Interest:
The authors declare no conflict of interest.

Abbreviations
The following abbreviations are used in this manuscript: