Flow structure analysis of nanofluid impingement on modified target surface under different design parameters.

The flow structures of jet impingement dominate heat and mass transfer process, even the whole thermal performance. In this study, we have inspected the flow structures and mechanism of nanofluid jet impingement onto a dimpled target surface with different design parameters. Investigations are performed for the relative depth of dimple (δ / D), the jet-to-plate spacing (H / d), nanoparticle volume concentration (ϕ), and Reynolds number (Re) ranging to explore the mechanism of flow structure variations. Results indicate that these parameters have a significant effect on the flow structure of nanofluid jet impingement near the dimpled target surface. The flow begins to separate after passing the edge of the dimple along with the curvature of a dimple. δ / D will affect the form and location of flow separation and reattachment, and ϕ will affect the intensity of separation flow. The length of the flow separation bubble varies in different H / d cases. When H / d increases, the impinging energy and the velocity near the dimple edge decreases. The different Re has little effect on the length of the flow separation bubble and the tendency of the pressure coefficient (Cp). These results can provide further mechanism inspiration for the design of the flow structure of nanofluid jet impingement. [ABSTRACT FROM AUTHOR]