ABSTRACT In coastal bay, circulation mainly occurs due to wave and wind induced current. As such two-dimensional model without wave effect fails to simulate the circulation pattern in a bay. Since the introduction of radiation stress concept to account for momentum flux due to waves by Longuet-Higgins and Stewart (1962), the stress terms are appropriately used to simulate coastal current (Birkemeir and Dalrymple, 1975). In a semi circular bay the wave with normal incidence will refract and diffract and propagate fanning out in the bay. It is observed that this phenomenon induces flow approaching from two sides and produce rip current at the middle. The two-dimensional wave period averaged radiation stress model has been developed to simulate this phenomenon. Effects of wave height and wave period on circulation pattern in a bay has been studied.