Nonlinear characteristics of periodically fully developed flow in cross-flow tube bundle

In this paper, a numerical study of periodically fully developed convective heat transfer is performed in horizontal cross flow across tube bundle. The developed mathematical mode is governed by the couple equations of continuity, momentum and energy and is solved numerically by employing SIMPLE algorithm with QUICK scheme. The effects of Reynolds number on fluid flow and heat transfer performance are investigated. It is found that at small Reynolds numbers does not have much influence on the flow field. While at high Reynolds numbers have considerable effect on the flow pattern and Nussle number, and appear unsteady-state. The unsteady state flow and heat transfer exhibited periodic oscillating or chaotic behaviors due to formation of the vortexes behind the tubes. Within the velocity boundary layer is torn because of the pressure evolving negatively at the tube area, large shear stresses occur. As a result, the first vortex cannot persist and emergence of an additional cell is observed when increasing Reynolds number. As a result, the flow and this disequilibrium is the source of instabilities. Fundamental studies on oscillatory convection are expected to clarify the general mechanism of oscillatory convection. Moreover, the deterministic chaos theory is used to the stability analysis in this paper. The maximum Lyapunov numbers are calculated in order to reflect the chaotic degrees.