$Ma$

Mach number

$R_E$

Eulerian correlation coefficient

$R_L$

Lagrangian correlation coefficient

$R_{ij}$

two-point correlation coefficient of $u_i$ and ${\omega }_j$ ( $i,j=1,2,3$ )

$Re$

Reynolds number

$R{e}_{\tau }$

Reynolds number defined with the friction velocity

$R{e}_{\theta }$

Reynolds number defined with the momentum loss thickness of turbulent boundary layer

t

time (s)

U

mean velocity (m∙s⁻¹)

$U_C$

propagation speed (m∙s⁻¹)

$\left(u_1,u_2,u_3\right)$ or $\left(u,v,w\right)$

velocity components in the streamwise, wall normal and spanwise directions, respectively (m∙s⁻¹)

$\left(x_1,x_2,x_3\right)$ or $\left(x,y,z\right)$

coordinates in the streamwise, wall normal and spanwise directions, respectively (m)

$\delta$

thickness of turbulent boundary layer (m)

$\nu$

kinematic viscosity (m²∙s⁻¹)

$\varphi$ or $\psi$

fluctuations of a variable or component

$\left({\omega }_1,{\omega }_2,{\omega }_3\right)$ or $\left({\omega }_x,{\omega }_y,{\omega }_z\right)$

vorticity components in the streamwise, wall normal and spanwise directions, respectively (s⁻¹)

Subscripts

i or j

coordinate indices, ( $i,j=1,2,3$ )

r

reference point

x, y, z

coordinate indices for the streamwise, wall normal and spanwise directions, also represented by 1, 2 and 3, respectively

Superscripts

+

normalized with wall units