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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Multiplicity and Stability of Forced Convection in Curved Ducts of Square Cross Section

Get access (open in a dialog) DOI: 10.1615/IHTC12.10
6 pages

Resumo

A numerical study is made on the fully developed bifurcation structure and stability of forced convection in a curved duct of square cross section. In addition to the extension of three known solution branches to the high Dean number region, three new asymmetric solution branches are found from three symmetry-breaking bifurcation points on the isolated symmetric branch. The flows on these new branches are either an asymmetric 2-cell state or an asymmetric 7-cell structure. The linear stability of multiple solutions is conclusively determined by solving the eigenvalue system for all eigenvalues. Only 2-cell flows on the primary symmetric branch and on the part of isolated symmetric branch are linearly stable. The linear stability is observed to change along some solution branches even without passing any bifurcation or limit points. Furthermore, dynamic responses of the multiple solutions to finite random disturbances are also examined by the direct transient computation. It is found that physically realizable fully-developed flows possibly evolve, as the Dean number increases, from a stable steady 2-cell state at a lower Dean number to a periodic oscillation, another stable steady 2-cell state, an intermittent oscillation, and a chaotic oscillation. Among them, three temporal oscillation states have not been reported in the literature. A periodic oscillation between symmetric/asymmetric 2-cell flows and symmetric/asymmetric 4-cell flows are found in the range where there are no stable steady fully developed solutions.