An Official Journal of the American Society of Thermal and Fluids Engineers

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Self-Similarity of Differential Equations and Heat Transfer Patterns of a Turbulent Near-Wall Layer

RESUMO

After looking at the works performed it becomes obvious that one of the most significant things is recast of a turbulent near-wall layer into locally self-similar one (depending on one coordinate). To solve this task, a number of steps were undertaken, such as determination of a new generalized coordinate, selection of constants and their determination. It should be noted that such recast of near-wall layer equations was carried out for the first time. The recast of equations of this type into locally self-similar ones enables one to ensure high accuracy of the iteration solution, however, powerful means are required — up-to-date computers and software. Such means had not been available previously, thus iteration solutions of quadratures were not performed. Application of the concurrent iteration solution method together with total solution of differential equations may be used with the objective of higher accuracy. Another important task is the determination of boundary heat transfer patterns in cases of variable physical properties. These patterns enable one to choose generalized heat transfer expressions. It was revealed that at high flow temperature turbulence and heat transfer decrease the velocity and temperature profiles change. This phenomenon has a practical value. At high flow temperatures there is no need to install turbulizers for intensification of heat transfer processes since no positive results will be obtained. The latter pattern comprises discovery elements.