Study of the effects of aspect ratio on hydrodynamic stability in curved rectangular ducts using energy gradient method

Abstract

We investigated the hydrodynamic instability of fluid flow in the 180° curved rectangular ducts under different aspect ratios using the energy gradient method. For this purpose, distribution of 3D energy gradient function K is computed by computational fluid dynamics (CFD). Our numerical results are properly validated against the existing experimental and numerical data. The results of current study indicate that Kmax is enhanced (destabilizing effect) by an increase in the aspect ratio from 0.2 up to 0.8. However, Kmax is decreased (stabilizing effect) by an increase in the aspect ratio from 0.8 up to 2. Values of Kmax and corresponding positions for the inception of Dean instability at different aspect ratios are also presented.

Keywords

• Hydrodynamic instability
• Curved duct
• Aspect ratio
• Energy gradient theory