# Effective viscosity in bubbly liquid

Motivation: I have screwed some crepes big time this morning and it made me think...

Consider a bubbly liquid (such as a crepes batter if you whisk it too much). Is there an approximate measure of the effective viscosity increase due to the bubbles in the flow? Obviously, if your characteristic length scale is much bigger than the typical size of a single bubble. Roughly speaking, something analogous to the eddy viscosity as known from the turbulence modeling?