Table of unit conversions

From openpipeflow.org
Revision as of 01:46, 7 June 2017 by Apwillis (talk | contribs)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search
The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

$ \renewcommand{\vec}[1]{ {\bf #1} } \newcommand{\bnabla}{ \vec{\nabla} } \newcommand{\Rey}{Re} \def\vechat#1{ \hat{ \vec{#1} } } \def\mat#1{#1} $

To convert the value of a dimensionless variable in 'code' units to 'lab' units, multiply by $C$ from the following table ('code' units are based on $R$ and $U_{cl}$, 'lab' units are based on $D$ and $U_b$).


E.g. for the variable $z$: $~~z_\mathrm{lab} \,(D) = z_\mathrm{code} \,(R) = z_\mathrm{code} \,(\frac{1}{2}D) ~~\Rightarrow~~z_\mathrm{lab} = z_\mathrm{code} \times \frac{1}{2},~~$ i.e. $~z_\mathrm{lab} = z_\mathrm{code} \times C$ with $C=\frac{1}{2}$.


$\begin{array}{ccccl} variable & \mbox{'code' units} & \mbox{'lab' units} & \mbox{conversion factor}~C & \mbox{comment}\\ \hline r,z & R & D & \frac{1}{2} & \mbox{length}\\ \vec{u} & U_{cl} & U_b & 2 & \mbox{speed} \\ t & R/U_{cl} & D/U_b & \frac{1}{4} & \mbox{time} \\ \sigma & U_{cl}/R & U_b/D & 4 & \mbox{growth rate} \\ E & \rho\,U_{cl}^2\, R^3 & \rho\,U_b^2\,D^3 & \frac{1}{2} & \mbox{kinetic energy} \\ D & \rho\,U_{cl}^3\, R^2 & \rho\,U_b^3\,D^2 & 2 & \mbox{dissipation rate} \\ E' & \rho\,U_{cl}^2\, R^2 & \rho\,U_b^2\,D^2 & 1 & \mbox{energy per unit length} \\ \tilde{E} & \rho\,U_{cl}^2 & \rho\,U_b^2 & 4 & \mbox{energy density} \end{array}$