Pressure-gradient driven channel flow

A pressure-gradient driven open channel flow is investigated here with a prescribed surface slope at a fixed water depth of m. No surface stress is applied, and rotation and stratification are neglected. The simulation is run for h until a steady-state is reached. The specification of all these parameters and those related to the turbulence models by use of the nml-files is analogous to section 12.1.1.

The surface slope is set in the namelist `ext_pressure` in the
input file `obs.nml`. How the parameters given in this file are
interpreted by GOTM is described in section 3.7 and briefly
also in `obs.nml`. This file typically contains information about
``observed'' quantities that are used to either force the model (like
internal and external pressure gradients) or for comparision with
computed results. In the latter case, ``observed'' quantities are
displayed in the output file next to the computed quantities.

If you want to try out the different turbulence models mentioned in
the couette-case (see section 12.1.1), simply copy the corresponding
files from the respective subdirectories to the current directory with
the GOTM executable. Note that in `gotmturb.nml` we now set `turb_method = 3`. This implies that the turbulent fluxes are computed
from a second-order turbulence model. A new thing in GOTM 3.2 is that
parameters for the second-order model can now be directly specified
via the ``scnd'' namelist in `gotmturb.nml`. For the theoretical
background of this, please see section 4.2

In the following publications some of the results in comparison to laboratory data are shown: Burchard et al. (1998), Burchard et al. (1999), Burchard (2002b). The simulation has been motivated by the work of Baumert and Radach (1992).

Karsten Bolding 2012-12-28