Abstract
In this article, a numerical study achieved to show the secondary flow behavior inside narrow gaps having complex shapes. The gaps are forming from a system of hot tubes compacted inside insulated container. All the possibilities of contact studied by local views for different sections along the container. The flexible grid generated by two differential equations in elliptic form which was suitable for all the complex sections presented in this study. Boundary fitted coordinate system used to distribute the grid orthogonally with all surfaces of contact. Niaver-Stocke equations together with the energy equation used to complete the solution after changing its first and second degree of partial derivative terms to computational domain using the Jacobia and metric transformations. Numerical solution completed with a steady flow assumption, for this purpose, a reasonable relaxation factors used to insurance axial slipping along the container benefiting from the parabolic form of energy equation. The local patterns show inequality in the effect and intensity of vorticity depending on the shape and location of the gaps. Vorticity generate from a hot streams, it mixing the heat between the tubes and its intensity agree directly with the gaps narrowing so that it disappear more rapidly compared with other gaps which contact with isolated wall. Finally, the results clear that Vorticity would not cause in enhancing in heat transfer coefficient directly with Rayliah number because its intensity depend on the shapes and locations of the gaps inside the container.