Direct numerical simulations of forced homogeneous isotropic turbulence in a dense gas

ABSTRACT

Direct Numerical Simulations (DNS) of forced homogeneous isotropic turbulence in a dense gas (FC-70), accurately described by a complex EoS, are computed for a turbulent Mach number of 0.8. In a numerical experiment, results are compared to the ones obtained when considering the fluid as a perfect gas. It is found that the dense gas displays a deeply modified shocklets' structure. The amplitude of compression shocklets jumps in pressure, density and entropy is divided by an order of magnitude with respect to the perfect gas. Moreover, expansion shocklets are found in the dense gas flow, also associated with small jumps in pressure, density and entropy. Comparing TKE spectra, the same inertial range is found regardless of the EoS. By comparing the terms of the filtered TKE equation for the dense and perfect gas EoS, it is found that for FC-70 and the present turbulent Mach and Taylor Reynolds numbers, the SGS deformation work is the only significant term in the inertial regime and does not significantly change with the EoS. A preliminary analysis of the flux terms responsible for the total energy conservation shows that the pressure term PDF is however significantly modified by the thermodynamic properties of the fluid.

Keywords:

• HIT
• compressible turbulence
• linear forcing
• dense gas
• BZT fluid

Acknowledgments

Some of the results detailed in this article have been presented at the second International Seminar on Non-Ideal Compressible-Fluid Dynamics held at Bochum, Germany in October 2018.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work is supported by the JCJC ANR EDGES project [grant number ANR-17-CE06-0014-01] of the French Agence Nationale de la Recherche. Simulations have been carried out using HPC resources at CINES under the project grant number A0042A07564.