  We investigate whether barred galaxies are statistically more likely to
harbour radial molecular gas flows and what effect those flows have on their
global properties. Using 46 galaxies from the ALMA-MaNGA QUEnching and STar
formation (ALMaQUEST) survey, we identify galaxies hosting optical bars using a
combination of the morphological classifications in Galaxy Zoo 2 and HyperLEDA.
In order to detect radial molecular gas flows, we employ full 3D kinematic
modelling of the ALMaQUEST CO(1-0) datacubes. By combining our bar
classifications with our radial bar-driven flow detections, we find that
galaxies classed as barred are statistically more likely to host large-scale
radial gas motions compared to their un-barred and edge-on galaxy counterparts.
Moreover, the majority of barred galaxies require multi-component surface
brightness profiles in their best-fit models, indicative of the presence of
resonance systems. We find that galaxies classed as barred with radial
bar-driven flows ("barred + radial flow" subset) have significantly suppressed
global star-formation efficiencies compared to barred galaxies without radial
bar-driven flows and galaxies in the other morphological sub-samples. Our
"barred + radial flow" subset galaxies also possess consistently centrally
concentrated molecular gas distributions, with no indication of depleted gas
mass fractions, suggesting that gas exhaustion is not the cause of their
suppressed star formation. Furthermore, these objects have higher median gas
mass surface densities in their central 1 kpc, implying that a central gas
enhancements do not fuel central starbursts in these objects. We propose that
dynamical effects, such as shear caused by large-scale inflows of gas, act to
gravitationally stabilise the inner gas reservoirs.
