Mean flow scaling in a spanwise rotating channel

Since the early work of Johnston [Johnston, Halleent, and Lezius, J. Fluid Mech. 56, 533 (1972)JFLSA70022-112010.1017/S0022112072002502], the mean flow scaling in a spanwise rotating channel has received much attention. While it is known that the mean velocity near the pressure, turbulent side follows a linear scaling U=2ωy+C at high rotation speeds, the functional dependence of C on the Reynolds number and the rotation number has been an open question. Here, U is the mean velocity, ω is the constant rotating speed in the spanwise direction, and C is a constant. In this work, we show that C+=log(lω+)/K, where the superscript + denotes normalization using wall units at the pressure side; lω=uτ,p/2ω is a rotation-induced length scale; K is a constant and K≈κ, where κ is the von Kármán constant; and uτ,p is the wall friction velocity at the pressure side.