Talk:Taylor microscale

Does viscosity matter at the Taylor microscale or not?

Reading the opening paragraph I was puzzled by the following statement:

"In fluid dynamics, the Taylor microscale, which is sometimes called the turbulence length scale, is a length scale used to characterize a turbulent fluid flow. This microscale is named after Geoffrey Ingram Taylor. The Taylor microscale is the intermediate length scale at which fluid viscosity significantly affects the dynamics of turbulent eddies in the flow."

This might very well be correct, rendering my apprehension unfounded. However, perusing a number of textbooks, I could not find a statement directly supporting this claim. On the contrary, Tennekes & Lumley (1972) p.68 state:

"The Taylor microscale is thus not a characteristic length of the strain-rate field and does not represent any group of eddy sizes in which dissipative effects are strong. It is not a dissipation scale, because it is defined with the assistance of a velocity scale which is not relevant for the dissipative eddies."

Which, even if it is not a direct contradiction, does not sound like it supports the sentiment either. Is it not the case that the Taylor microscale should exist somewhere in the inertial range where turbulent motions are governed by dissipation, and dissipation only? I also checked my edition of Turbulent Flows by Pope (2015), which, on p.186-187, states:

"...according to the second similarity hypothesis, motions in the inertial subrange are determined by inertial effects — viscous effects being negligible — whereas only motions in the dissipation range experience significant viscous effects, and so are responsible for essentially all of the dissipation."

If there is some fundamental part of the theory I have misunderstood, please correct me (preferably with a textbook or research paper reference). Petterrb (talk) 11:22, 21 April 2026 (UTC)