  In this paper, the shock dynamics due to the movement of a bump over a flat
plate flying at supersonic speed are numerically investigated. The bump is
located at the impingement position of the shock wave and is moved at different
speeds. This study determines the suitable speed that achieves the minimum
entropy change, which is the representation parameter of the transition period.
The two-dimensional unsteady Navier-Stokes equations are solved using OpenFOAM
to simulate the flow field variables, while the motion of the bump is tracked
using the Arbitrary Lagrangian-Eulerian (ALE) technique. The results show that
a spatial lag on the shock system from the steady-state solution occurs due to
the movement of the bump. Further, the spatial lag increases with the increase
in the bump's speed. This causes a high increase in the flow parameters and
consequently the total entropy changes on the bump surface. Generally, it is
common to move the bump over the longest possible time to approximate a
quasi-steady flow during the motion. However, this causes a deviation in the
flow parameters between the final time of transition and the steady-state case
of bump existence. Thus, it is concluded that the optimal non-dimensional time
for a morphing bump in a supersonic flow of Mach number of 2.9 is 2, which is
different than the longest time of 10.

Fluid Dynamics