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fvOptions: verticalDamping: Documentation fixes

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Will Bainbridge
2017-09-20 16:01:18 +01:00
parent 843d831172
commit cc400016f4
1 changed files with 9 additions and 7 deletions
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16
src/fvOptions/sources/derived/verticalDamping/verticalDamping.H
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@ -32,9 +32,10 @@ Description
Damping is achieved by applying a force to the momentum equation
proportional to the momentum of the flow in the direction of gravity. The
constant of proportionality is given by a coefficient, lambda, which has
units of inverse-time. In the absence of any other forces this would
constant of proportionality is given by a coefficient \f$\lambda\f$ which
has units of inverse-time. In the absence of any other forces this would
generate an exponential decay of the vertical velocity.
\f[
\frac{d (m u_z)}{d t} = - \lambda m u_z
\f]
@ -42,11 +43,12 @@ Description
u_z = u_{z0} e^{- \lambda t}
\f]
Lambda should be set based on the desired level of damping and the residence
time of a perturbation through the damping zone. For example, if waves
moving at 2 [m/s] are travelling through a damping zone 8 [m] in length,
then the residence time is 4 [s]. If it is deemed necessary to damp for 5
time-scales, then lambda should be set to equal 5/(4 [s]) = 1.2 [1/s].
The coefficient \f$\lambda\f$ should be set based on the desired level of
damping and the residence time of a perturbation through the damping zone.
For example, if waves moving at 2 [m/s] are travelling through a damping
zone 8 [m] in length, then the residence time is 4 [s]. If it is deemed
necessary to damp for 5 time-scales, then \f$\lambda\f$ should be set to
equal 5/(4 [s]) = 1.2 [1/s].
Usage
Example usage: