How does the size of the soil particles impact
the soil's permeability (movement of water)?

Water moves by gravity into the open pore spaces in the soil, and the size of the soil particles and their spacing determines how much water can flow in. Wide pore spacing at the soil surface increases the rate of water infiltration, so coarse soils have a higher infiltration rate than fine soils.

How does soil particle size affect permeability?

But permeability is a different thing. It increases as particle size increases. By definition, permeability is a MEASURE OF EASE with which fluids will flow though a porous rock, soil or sediment. ... That means capillarity increase as particle sizes decreases.

equal distribution i think.