In this study, a boundary layer flow over a flat plate is investigated numerically at constant inlet freestream velocity and turbulence intensity. After intensive mesh refinements, an adequate computational domain is determined. Four turbulence models (k-epsilon, k-omega, k-omega SST, Transition SST) are used to analyze the boundary layer flow. Local surface friction coefficient distribution is obtained and compared to each other to assess the most convenient turbulence model. The Computational Fluid Dynamics (CFD) results show that the Transition SST turbulence model demonstrates the most realistic surface friction coefficient (Cf) distribution in agreement with the experimental data. Additionally; the effects of constant heat fluxes on Cf values are investigated and it is found that the heating process moves transition backward compared to isothermal case. Moreover, it is fount that Cf values in the turbulent region decrease compared to isothermal case.
In this study, Computational Fluid Dynamics (CFD) calculations are performed with ANSYS-Fluent for an external flow over a flat plate under constant surface temperature conditions. By using an Active Flow Control (AFC) method, the flat-plate is heated to manipulate the transition region. Calculations are performed for a steady and turbulent flow at 15 m/s free-stream velocity. Local skin friction coefficient and local heat transfer coefficient distributions along the flat-plate are investigated for laminar and turbulent boundary layers at various constant surface temperatures. For laminar and turbulent flow boundary layer characteristics, theoretical correlations in the literature are used to verify the numerical results. Results show that theoretical correlations are highly consistent with CFD results only in the laminar and turbulent regions and it is also shown that transition can only be predicted by CFD simulations. On the other hand, heating as an AFC method is found to be useful in delaying transition regime over a flat plate.
In this study, numerical calculations are performed to investigate steady, laminar convective heat transfer characteristics in rectangular micro channel heat sinks under constant heat fluxes. The investigations are performed at three different inlet Reynolds numbers (400,600 and 800) and constant heat fluxes (500, 1000 and 2000 kW/m2). The aspect ratios of the rectangular micro-channel are selected 1, 1.5 and 2 in the laminar flow regime, respectively. Heat transfer enhancement is the main objective of the study. Nusselt number variation and the pressure drops are found for the given parameters to find the best heat transfer enhancement. It is found that a micro-channel heat sink with square cross-sectional area can be used as an adequate configuration under laminar flow conditions.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.