Numerical Study of the Hydrodynamic and Thermal Proprieties of Titanium Dioxide Nanofluids Trapped in a Triangular Geometry

摘要

In the present work, we investigate numerically the fluid flow and heat transfer inside an entrapped cavity, which has an isosceles triangular cross-section and is filled with TiO_2-water nanofluid. The base wall is maintained at high constant temperature, while the two other sides are kept a lower constant temperature. The length of the cavity is large enough to assume that the flow is two-dimensional. The governing equations are discretized by the finite volume method and solved numerically via the SIMPLER algorithm. In the present work, we investigate the effect of some parameters including theRayleigh number, the solid volume fraction, the cavity aspect ratio and the inclination angle on both the thermal performance and the flow structure. The obtained results show that the thermal performance of the cavity and the flow structure are most sensitive to Rayleigh number and solid volume fraction. On the other hand, the aspect ratio of the cavity and its inclination also affect considerably the heat transfer and fluid flow pattern. We notice the occurrence of a pitchfork bifurcation phenomenon, which is a function of both Rayleigh number and cavity aspect ratio. Our results provide information that may be useful for design optimization as well as for thermal performance enhancement of energy systems such as solar water heaters.