This paper pioneers the direct numerical simulation (DNS) and physical
analysis in supersonic three-temperature carbon dioxide (CO2) turbulent channel
flow. CO2 is a linear and symmetric triatomic molecular, with the thermal
non-equilibrium three-temperature effects arising from the interactions among
translational, rotational and vibrational modes under room temperature. Thus,
the rotational and vibrational modes of CO2 are addressed. Thermal
non-equilibrium effect of CO2 has been modeled in an extended three-temperature
BGK-type model, with the calibrated translational, rotational and vibrational
relaxation time. To solve the extended BGK-type equation accurately and
robustly, non-equilibrium high-accuracy gas-kinetic scheme is proposed within
the well-established two-stage fourth-order framework. Compared with the
one-temperature supersonic turbulent channel flow, supersonic three-temperature
CO2 turbulence enlarges the ensemble heat transfer of the wall by approximate
20%, and slightly decreases the ensemble frictional force. The ensemble density
and temperature fields are greatly affected, and there is little change in Van
Driest transformation of streamwise velocity. The thermal non-equilibrium
three-temperature effects of CO2 also suppress the peak of normalized
root-mean-square of density and temperature, normalized turbulent intensities
and Reynolds stress. The vibrational modes of CO2 behave quite differently with
rotational and translational modes. Compared with the vibrational temperature
fields, the rotational temperature fields have the higher similarity with
translational temperature fields, especially in temperature amplitude. Current
thermal non-equilibrium models, high-accuracy DNS and physical analysis in
supersonic CO2 turbulent flow can act as the benchmark for the long-term
applicability of compressible CO2 turbulence.Comment: Carbon dioxide flow, Vibrational modes, Three-temperature effects,
Supersonic turbulent channel flow