  Clogging is a common obstacle encountered during the transport of suspensions
and represents a significant energy and material cost across applications,
including water purification, irrigation, biopharmaceutical processing, and
aquifer recharge. Pulsatile pressure-driven flows can help mitigate clogging
when compared to steady flows. Here, we study experimentally the influence of
the amplitude of pulsation $0.25\,P_0 \leq \delta P \leq 1.25\,P_0$, where
$P_0$ is the mean pressure, and of the frequency of pulsation $10^{-3}\,{\rm
Hz} \leq f \leq 10^{-1}\,{\rm Hz}$ on clog mitigation in a microfluidic array
of parallel channels using a dilute suspension of colloidal particles. The
array geometry is representative of a classical filter, with parallel pores
that clog over time, yielding a filter cake that continues to grow and can
interact with other pores. We combine flow rate measurements with direct
visualizations at the pore scale to correlate the observed clogging dynamics
with the changes in flow rate. We observe that all pulsatile amplitudes at
$0.1$ Hz yield increased throughput compared to steady flows. The rearrangement
of particles when subject to a dynamic shear environment can delay the clogging
of a pore or even remove an existing clog. However, this benefit is drastically
reduced at $10^{-2}$ Hz and disappears at $10^{-3}$ Hz as the pulsatile
timescale becomes too large compared to the timescale associated with the
clogging and the growth of the filter cakes in this system. The present study
demonstrates that pulsatile flows are a promising method to delay clogging at
both the pore and system scale.
