Some degree of clumping gets naturally created when you use Frizz at low frequencies, but you can go a bit further here with the Multi Strand parameters. For each hair that is normally rendered, Multi Strand renders a clump of additional hairs scattered around the original hair. The Splay settings control the degree of scattering at the roots and tips, and Multi Strand Count controls the number of hairs to create for the clump. You can use Splay to shape the clump by spreading or compressing the roots and tips.
1. Multi Strand Count=0, Hair Count=500
2. Multi Strand Count=10, Root Splay=0.1, Tip Splay=0.1, Hair Count=500
3. Multi Strand Count=10, Root Splay=0.4, Tip Splay=0.1, Hair Count=500
4. Multi Strand Count=10, Root Splay=0.0, Tip Splay=1.0, Hair Count=500