Constraining turbulence mixing strength in transitional discs with planets using SPHERE and ALMA

We investigate the effect that the turbulent mixing strength parameter α_turb plays on near-infrared polarimetric and sub-millimetre interferometric imaging observations of transitional discs (TDs) with a gap carved by a planet. We generate synthetic observations of these objects with ALMA and VLT/SPHERE-ZIMPOL by combining hydrodynamical, dust evolution, radiative transfer and instrument models for values of α_turb=[10⁻⁴,10⁻³,10⁻²]⁠. We find that, through a combination of effects on the viscosity of the gas, the turbulent mixing and dust evolution processes, αturb strongly affects the morphology of the dust distribution that can be traced with these observations. We constrain the value of α_turb to be within an order of magnitude of 10−3 in TD sources that show cavities in sub-mm continuum images while featuring continuous distribution of dust or smaller cavities in NIR-polarimetric images.