# Does a decreasing shape factor correspond to greater or reduced probability of separation?

The shape factor ($$H=\frac{\delta^*}{\theta}$$) is the ratio of displacement thickness, a measure of the thickness of the boundary layer, to the momentum thickness, a measure of the shear stress. I think that a larger shape factor indicates that the boundary layer is larger and there is less shear stress, so it seems like a larger shape factor should be associated with a greater likelihood of separation. Is that right? If not, why?

• There is no need to close this question. It is very clear what OP is asking. – Koyovis Jul 28 at 4:25
• @Koyovis It might be that I used the separation tag wrong. – kilojoules Jul 28 at 21:04