Effect of wind shear coefficient on wind velocity at coastal sites of Bangladesh

In this paper, the wind shear coefficient has been determined and analyzed at coastal wind sites of Bangladesh. For searching the wind energy for scale-up contribution to renewable energy in rural, pre-urban and urban areas some research work has been done. This is in line with the proposed renewable energy policy of Bangladesh targeting on solar-wind hybrids power generation by renewable energy to meet 5% of the total power demand by 2015. In this work, considering a coastal wind site such as Kuakata where wind shear coefficient has been determined and the effect of wind shear on velocity profile has been analyzed. It is evident that the heating and cooling cycle of the air adjacent to the earth during 24 h of the day influences the wind shear coefficients. During early hours of the day i.e. between 00:00 and 07:00 h, higher and almost constant values of α1, α2 and α3 were observed while from 07:00 h onwards, as heating of the ground surface and the air above it took place, these values started decreasing and after reaching a minimum at 09:00 h remained almost constant up to 18:00 h for α2. But at 12:00 h the wind shear coefficient becomes minimum both α1 and α3. After 16:30 h, the values of α1 and α3 again started increasing and after reaching a maximum at 21:00 h showed a decreasing pattern during rest of the night hours, which may be accounted for cooling of the ground surface and the air above it.