TOWARDS THE DEVELOPMENT OF RANS MODELS FOR CONJUGATE HEAT TRANSFER
Timothy J. Craft Turbulence Mechanics Group, School of Mechanical, Aerospace and Civil Engineering, The University of Manchester, PO Box 88, Manchester M13 9PL, UK
Hector Iacovides Turbulence Mechanics Group, School of Mechanical, Aerospace and Civil Engineering. The University of Manchester, Manchester M13 9PL, U.K.
Sakchai Uapipatanakul Turbulence Mechanics Group, School of Mechanical, Aerospace & Civil Engineering, The University of Manchester, Manchester M60 1QD, UK
AbstraktThe present study is concerned with exploring the ability of eddyviscosity based RANS models to compute conjugate heat transfer problems, including capturing the decay of turbulent temperature fluctuations across the wall region. This is done by extending the application of the modelled transport equations for temperature variance and its dissipation rate across the solid wall region, thus providing the decay of the variance across this region.
Comparisons are drawn with existing DNS data of plane channel flow, at a relatively low Reynolds number, heated through a wall of nonzero thickness. Cases are simulated covering a range of thermal activity ratios, representing a range of different solid/fluid thermal conductivity/diffusivity ratios. It is found that, in order to predict the correct decay of temperature variance across the wall, an accurate representation of it, and of its dissipation rate, in the nearwall fluid flow region is required. This, in turn, also requires an accurate representation of the nearwall dynamic field turbulence.
A number of modifications are proposed to an existing fourequation k−ε−θ^{2}−ε_{θ} model in order to provide good nearwall predictions of the four variables under the two limiting thermal boundary treatments of isothermal and isoflux conditions. The resulting scheme is shown to perform well in the conjugate calculations over a range of thermal activity ratios.
