Air Bubble Effects on Long Waves

The study has investigated the severe long waves formed during Cyclone Aila in 2009 that crossed the coastal region of Bangladesh. A comparison is made between the surges with and without air bubbles to investigate the behavior of surge height during storm surge. We have found the significant effects of air bubble on water level variation at different locations in the coastal region of Bangladesh. Finite difference method is used where the coasts and islands are included in the model following the stair step method. The dynamic effect of pressure gradient outside the storm surge region in the model is found negligible in comparison with the dominant effect of wind. It was observed that approximately 1.5%-3.5% water level increases with the increasing of void fraction from 10%-70% associated during Aila. The results are in good agreement with the field validation as reported from post storm survey information.