  The transition of hypersonic boundary layer can lead to a several-fold
increase in surface heat flux and skin friction for the aircraft, significantly
impacting its flight performance. The corrugated wall, as a passive control
method for boundary layer flow, also serves as a type of wall microstructure,
making its study on the local rarefaction effect of considerable engineering
significance. In this study, we employed the conservative discrete unified gas
dynamic scheme and utilized a domain-wide numerical simulation method.
Initially, we simulated the hypersonic flat plate flow with different depths of
corrugated walls under the conditions of incoming flow Mach number of 6 and
Reynolds number of ${{10}^{7}}$. Subsequently, we investigated the effects of
corrugated walls, including flat plate corrugated walls and wedge corrugated
walls, under varying Reynolds numbers for an incoming flow Mach number of 6,
and discussed the impact of local rarefaction effect of corrugated walls under
different Reynolds numbers. By using the local Knudsen number as the criterion,
we found that under these conditions, the occurrence of local rarefaction
effect near the corrugated wall due to consecutive failures does not take place
when the incoming Reynolds number reaches ${{10}^{7}}$ or ${{10}^{6}}$.
However, when the incoming Reynolds number drops to ${{10}^{5}}$, the local
rarefaction effect near the corrugated wall becomes evident, with the
appearance of non-equilibrium effects in translational and rotational
temperatures of molecules. This phenomenon becomes more pronounced as the
Reynolds number decreases further.
