Direct numerical simulation for a time-developing combined-convection boundary layer along a vertical flat plate

• Published in: International journal of heat and mass transfer Vol. 53; no. 9; pp. 2113 - 2122
• Main Authors: Abedin, Mohammad Zoynal, Tsuji, Toshihiro, Hattori, Yasuo
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.04.2010; Elsevier
• Subjects: Boundary layer; Boundary layer and shear turbulence; Combined convection; Computational fluid dynamics; Convection and heat transfer; Convective heat transfer; Direct numerical simulation; Exact sciences and technology; Flat plates; Fluctuation; Fluid dynamics; Fluid flow; Fundamental areas of phenomenology (including applications); Mathematical analysis; Physics; Transition; Turbulence; Turbulent boundary layer; Turbulent flow; Turbulent flows, convection, and heat transfer; Combined convection; Convective heat transfer; Turbulent boundary layer; Transition; Direct numerical simulation; Temperature distribution; Turbulent flow; Nusselt number; Digital simulation; Air; Velocity distribution; Reynolds stress; Heating surface; Modelling; Vertical plate; Boundary layers; Heat transfer
• ISSN: 0017-9310; 1879-2189
• DOI: 10.1016/j.ijheatmasstransfer.2009.12.044

Time-developing combined-convection boundary layers induced by imposing aiding and opposing flows to the natural-convection boundary layer in air along a hot vertical flat plate have been examined with a direct numerical simulation. As the freestream velocity increases, the transition from laminar to turbulence delays for aiding flow and quickens for opposing flow, corresponding well to actual observations in space-developing flows. The calculated profiles of mean streamwise velocity, mean temperature, intensities of streamwise velocity fluctuation and temperature fluctuation in the laminarization process of the boundary layer for aiding flow agree relatively well with the existing data. Also, the distributions of turbulent statistics and instantaneous fluid motions in the combined-convection boundary layers with adding and opposing flows are displayed, and the regimes of the boundary layer flows obtained from the calculations are compared with those observed in the experiment.