Amplifications of turbulence across a normal shock in thermal non-equilibrium using direct numerical simulations*

Shock-turbulence interactions are important phenomena in engineering applications and natural systems.

One universal observation is the amplification of turbulence which can be described by a similarity variable K which is combination

of all governing parameters, namely, the Reynolds number, and the turbulent and mean Mach numbers (Chen & Donzis 2019).

At high speeds, temperature increases and molecular vibrational energy becomes important and start affecting the dynamics of the flows.

Due to long temporal relaxation in vibrational energy, the flows are in a state of thermal non-equilibrium.

We present a study of shock-turbulence interactions with activated vibrational energy using direct numerical simulations.

The discussion will focus on turbulence amplifications by shock compression and the contributions from vibrational energy.

Our results show that the K factor remains important to describe the evolution of turbulent fluctuations.

However, the interactions also exhibit dependencies on vibration energy and the corresponding relaxation process.

These observations will be discussed in the context of so-called wrinkled and broken regimes in which the shock experiences structural changes

and the challenges associated with identifying the interactions of shocks and turbulence with vibrational energy.