Journal of Applied Sciences1812-56541812-5662Asian Network for Scientific Information10.3923/jas.2007.2437.2443MondalR.N.M.A. HudaS.F. AhmmedS.M.A. RahmanMunnujahan Ara122007717Unsteady solutions of the thermal flows through a curved rectangular duct of aspect ratio 2 is investigated numerically by using the spectral method over a wide range of the Dean number, 0≤Dn≤1000, with a temperature difference between the vertical sidewalls for the Grashof number, 1000≤Gr≤1500. The outer wall of the duct is heated while the inner wall is cooled. In the present study, unsteady solutions of the thermal flows for a single case of the Grashof number Gr = 1500 is investigated in detail and complete flow behavior, covering the wide range of Gr, is shown by a phase diagram. It is found that the steady flow turns into chaotic flow through periodic or multi-periodic flows for large or moderate Gr; for small Gr, however, the steady flow turns into chaotic state through various flow instabilities, if Dn is increased.]]>Chandratilleke, T.T. and Nursubyakto,2003Dennis, S.C.R. and M. Ng,1982Finlay, W.H. and K. Nandakumar,1990Gottlieb, D. and S.A. Orszag,1977Kao, H.C.,1992Ligrani, P.M. and R.D. Niver,1988Mondal, R.N.,2006Mondal, R.N., Y. Kaga, T. Hyakutake and S. Yanase,2006Mondal, R.N., D. Tarafder, M.A. Huda, M. Samsuzzoha and M. Sharif-Uddin,2007Nandakumar, K. and H.J. Masliyah,1982Wang, L. and T. Yang,2005Yanase, S. and K. Nishiyama,1988Yanase, S., N. Goto and K. Yamamoto,1989Yanase, S., Y. Kaga and R. Daikai,2002Yanase, S., R.N. Mondal and Y. Kaga,2005Yamamoto, K., T. Akita, H. Ikeuchi and Y. Kita,1995