Mean velocity and temperature scaling for near-wall turbulence with heat transfer at supercritical pressure

Abstract

Compared with conventional gaseous and liquid fluids, fluids operating at supercritical pressure undergo drastic variations in thermophysical properties within a small temperature range across the pseudo-critical point. Therefore, the effect of these variations on flow and heat transfer must be studied. This paper presents direct numerical simulations (DNSs) of the turbulent heat transfer of CO2 at supercritical pressure in a fully developed channel flow between two isothermal walls. The thermophysical property tables generated from the REFPROF 9.1 database were used in this DNS. The velocity and temperature scaling and the analogy between momentum and scalar transport are comprehensively explored by using stress balance and semi-local methods. The results show that at small temperature differences, the velocity transformation developed by Trettel and Larsson [“Mean velocity scaling for compressible wall turbulence with heat transfer,” Phys. Fluids 28, 026102 (2016)] with a semi-local coordinate provides a good description of the near-wall turbulence of supercritical fluids. Upon including how large specific-heat variations affect temperature transformation, the logarithmic region of the cooled wall becomes consistent, as does the heated wall in a certain temperature range. In addition, in near-wall turbulence with small temperature differences at supercritical pressure, momentum transport is highly analogous to scalar transport.