Numerical Simulation of Coastal Current due to wind in the Coasts of Astara

Volume 2, Issue 3 - Serial Number 3
Autumn 2019
Pages 258-271

Document Type : Original Article

Authors

1 Islamic Azad University, Science and Research Branch, Tehran

2 Faculty of Marine Science and Technology, Islamic Azad University, North Tehran Branch,

3 Department of Marine Science & Technology, Islamic Azad University, Tehran North Branch, Tehran, Iran

4 Institute of Geophysics, Tehran University, Tehran

Abstract
This research sets out to examine spatio-temporal pattern of wind induced currents in Astara port and coastlines adjacent to the port. Wave breaking occurs when wave amplitude reaches the point that the crest of wave actually overturns, and as a consequence it generates radiation stress and current on the surface of water. By collecting required data and validation of the ECMWF wind, wave simulating was applied to Caspian Sea and radiations stress was extracted to model current in the entire Caspian Sea for average of 10 years during the 2003-2013 periods. Boundary conditions extracted from large scale flow model was used to simulate wave-induced current in the Astara region. The results showed that although the current was severe in autumn, it was calm in summer. Prevailing directions of the current on the coast of the port was determined south and southwest respectively. Furthermore, pattern of weaker coastal currents included small vortices in the region. The highest frequency of wave height in the studied stations was between 0.3 to 0.6 m in all months of the year and the highest calm sea condition was observed in summer at 33.64%. The highest current velocity due to wave breaking with a value of 0.3 m / s has been observed in the northern station of Astara port for winter. The main direction of flow on the shores of Astara port was determined as south and southwest. The strongest coastal currents will occur in autumn and the calm currents will prevail in the region in summer. There are no field measurements on the Astara coast from the current profile to compare the results. Therefore, comparing the results of this study with modeling studies for wind-induced currents in the south of the Caspian Sea and the entire Caspian Sea for the current velocity due to wind in Astara region shows an error of about 25%.

Keywords