Contrasting turbulence–radiation interaction in supersonic channel and pipe flow

The Large Eddy Simulation (LES) technique is used to explore similarities and differences between turbulence–radiation interaction (TRI) in fully developed supersonic plane channel flow and axisymmetric non-swirling pipe flow, bounded by isothermal black and diffusive walls which are kept at a temperature of 800 K. The comparison between both flows is based on equal friction Mach number, friction Reynolds number, Prandtl number and ratio of specific heats. The Reynolds number is defined with the channel half-width and pipe radius. An explicit filtering scheme based on approximate deconvolution is applied to treat the closure problem of the low-pass filtered compressible Navier–Stokes equations. The working fluid is water vapour and its radiative properties are accounted for using a grey gas model with a Planck mean absorption coefficient varying with temperature. Simulations have been performed for two different optical thicknesses. Results for mean flow quantities, Reynolds stresses and pressure–strain correlations are presented, contrasting radiative effects in both flows and indicating their interaction with curvature effects in the pipe. An analysis of the total enthalpy balance reveals the role of radiative heat transfer, compared to turbulent and mean molecular heat transport.