Wall Layer

Wall Layer is the one is closest to the wall. In this layer the flow is dominated by viscous shear force. From Fig. it is clear that shear stress ia almost constant in this layer. By defining a friction velocity as

$$u^* = \sqrt{\tau_w \over \rho}$$ (7.30)

it is established that for this layer,

$$u^{+} = y^{+}$$ (7.31)

$$u^+ = { u \over u^*},   \texttt{and},  y^{+} = {{y u^*} \over \nu}$$ (7.32)

recalling that $\nu = \mu /\rho$. The wall layer extends from the wall to a y⁺ of about 5 and merges with the logarithmic profile in the Overlap region at around a y⁺ of 30.

(c) Aerospace, Mechanical & Mechatronic Engg. 2005
University of Sydney