The algebraic k-equation

INTERFACE:

   subroutine tkealgebraic(nlev,u_taus,u_taub,NN,SS)

DESCRIPTION:

This subroutine computes the turbulent kinetic energy based on (150), but using the local equilibrium assumption

$$P+G-\epsilon=0 \quad .$$ (169)

This statement can be re-expressed in the form

$$k= (c_\mu^0)^{-3} \, l^2 ( c_\mu M^2 - c'_\mu N^2 ) \; , \quad$$ (170)

were we used the expressions in (152) together with (43) and (44). The rate of dissipaton, $\epsilon$, has been expressed in terms of $l$ via (153). This equation has been implemented to update $k$ in a diagnostic way. It is possible to compute the value of $k$ as the weighted average of (170) and the value of $k$ at the old timestep. The weighting factor is defined by the parameter c_filt. It is recommended to take this factor small (e.g. c_filt = 0.2) in order to reduce the strong oscillations associated with this scheme, and to couple it with an algebraically prescribed length scale with the length scale limitation active (length_lim=.true. in gotmturb.nml, see Galperin et al. (1988)).

USES:

   use turbulence,   only: tke,tkeo,L,k_min
   use turbulence,   only: cmue2,cde,cmue1,cm0
 
   IMPLICIT NONE

INPUT PARAMETERS:

 
   number of vertical layers
   integer,  intent(in)                :: nlev
 
   surface and bottom
   friction velocity (m/s)
   REALTYPE, intent(in)                :: u_taus,u_taub
 
   square of shear and buoyancy
   frequency (1/s^2)
   REALTYPE, intent(in)                :: NN(0:nlev),SS(0:nlev)

DEFINED PARAMETERS:

   REALTYPE , parameter                :: c_filt=1.0

REVISION HISTORY:

   Original author(s): Hans Burchard & Karsten Bolding
   $Log: tkealgebraic.F90,v $
   Revision 1.7  2007-01-06 11:49:15  kbk
   namelist file extension changed .inp --> .nml
   Revision 1.6  2005/06/27 13:44:07  kbk
   modified + removed traling blanks
   Revision 1.5  2003/03/28 09:20:35  kbk
   added new copyright to files
   Revision 1.4  2003/03/28 08:29:16  kbk
   removed tabs
   Revision 1.3  2003/03/10 09:02:05  gotm
   Added new Generic Turbulence Model + improved documentation and cleaned up code
   Revision 1.2  2002/02/08 08:59:58  gotm
   Revision 1.1.1.1  2001/02/12 15:55:58  gotm
   initial import into CVS