The "Cottbus Geophysical Facility 2a" (CoGeoF2a)

also/formally known as "large spherical gap"

Further Information

M. Sc. Michael Hoff
T +49 (0) 355 69 4626
F +49 (0) 355 69 4891
LG3D, Raum 13

inner radius ri40 and 60 [mm]
outer radius ro120 [mm]
gap width d60 and 80 [mm]
radius ratio η0.5
inner rotation rate Ωi200 [rpm]
outer rotation rate Ωo60 [rpm]
Libration of inner sphere60 ± 60 [rpm]

Co-, differential and conter rotating system

Reynolds number

\begin{displaymath}Re = {{r_i^2 \Omega} \over {\nu}}\end{displaymath}

Taylor number in co-rotating system

\begin{displaymath}Ta = {{4d^4 \Omega^2} \over {\nu^2}}\end{displaymath}

Taylor number in differential rotating system

\begin{displaymath}Ta = {{4d_o^4 \Omega^2} \over {\nu^2}}\end{displaymath}

Rossby number

\begin{displaymath}Ro = {{\Omega_i - \Omega_o} \over {\Omega_o}}\end{displaymath}

Ekman number in differential rotating system

\begin{displaymath}E = {{\nu} \over {d \Omega_o}}\end{displaymath}


\begin{displaymath}\Omega_1 (t) = \Omega_0 + \epsilon \cdot cos(\omega t)\end{displaymath}