The present work considers the low Reynolds number wake flow behind a squareback
Ahmed body, in close proximity to a ground. At low Reynolds numbers such wakes are
known to undergo a series of bifurcations to a state that breaks reflectional symmetry.
The symmetry breaking of the wake also persists at turbulent high Reynolds numbers,
where it manifests as bi-modal behaviour with random switching between the asymmetric
states. Thus far, it has only been possible to study the low Reynolds number sequence
of bifurcations experimentally and mathematically. The present work presents the first
numerical simulations capturing the sequence of symmetry breaking bifurcations that
occur. A study of how the wake topology changes throughout suggests that interaction
between the closer top/bottom pair of parallel shear layers can only dominate once there
is sufficient underbody flow. When this occurs, the two main vortex structures in the wake
switch from being horizontally to vertically aligned. A linear feedback control strategy,
designed to attenuate base pressure force fluctuations, is then implemented. This causes
an accompanying reduction in drag and re-symmetrisation of the wake. Analysis using the
Dynamic Mode Decomposition confirms that the wake shedding mode is re-symmetrised.
This work motivates future attempts to capture wake symmetry breaking and bi-modality
in numerical simulations, and application of a promising feedback control strategy at
higher, turbulent Reynolds numbers.