  This study investigates the origin and sustenance of self induced
oscillations of shock structures in a hypersonic flow over a double wedge
configuration. Previously, various researchers have considered the double wedge
flow configuration for inviscid flow with variations of different inflows as
well as geometric parameters such as inflow Mach number , wedge angles, and
wedge lengths. Few recently published articles reveal an unsteady flow physics
involved with the hypersonic viscous flow for double wedge configuration with
large second wedge angles. However, the reason for such self sustained flow
oscillations is not completely clear. The present work seeks out to investigate
the origin of such oscillations in a low enthalpy hypersonic flow with
different aft wedge angles and wedge length ratios.In the current study,
viscous flow over a double wedge at Mach 7 and fore wedge angle of 30{\deg} is
considered. An improved version of rhoCentralFoam solver in OpenFOAM is used to
investigate the double wedge flow over different grid resolutions in the
separation region and shock shock interaction region. This study corroborates
the observation from the previous literature with an improvement in the range
of parameters which results in a self sustained periodic oscillation. The
present study also suggests that the unsteadiness becomes possible when the
incidence shock is in the proximity of the aft wedge expansion corner as a
consequence of different wedge length ratios(L1/L2) or aft wedge angles
({\theta}2). Flow can still be steady at a large aft wedge angle if the
incidence shock is far ahead of the aft wedge expansion corner.
