Mass affect in tyFlow works as intended. The algorithm is simple: acceleration = force * 1/mass, which is typical for simulation software. Note that given that algorithm, particles with less mass will travel faster than those with more mass when pushed by forces like wind, which is what you'd expect in nature - objects with more mass are subject to more inertia.
That said, the force of gravity, in nature, does not discriminate based on mass. Heavier objects fall at the same speed as lighter objects. The mistake might be assuming that heavier objects would fall faster.
That said, the force of gravity, in nature, does not discriminate based on mass. Heavier objects fall at the same speed as lighter objects. The mistake might be assuming that heavier objects would fall faster.