# Changeset 206 for palm/trunk/DOC/app/chapter_3.9.html

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Timestamp:
Oct 13, 2008 2:59:11 PM (14 years ago)
Message:

ocean-atmosphere coupling realized with MPI-1, adjustments in mrun, mbuild, subjob for lcxt4

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• ## palm/trunk/DOC/app/chapter_3.9.html

 r197 PALM includes a so-called turbulence recycling method which allows a turbulent inflow with non-cyclic horizontal boundary conditions. The method follows the one described by Lund et al. (1998, J. Comp. Phys., 140, 233-258), modified by Kataoka and Mizuno (2002, Wind and Structures, 5, 379-392). The method is switched on by setting the initial parameter turbulent_inflow = .TRUE..

The turbulent signal A'(y,z) to be imposed at the left inflow boundary is taken from the simulation at a fixed distance xr from the inflow (given by parameter recycling_width): A'(y,z) = A(xr,y,z) - A(z), where A(z) method follows the one described by Lund et al. (1998, J. Comp. Phys., 140, 233-258), modified by Kataoka and Mizuno (2002, Wind and Structures, 5, 379-392). The method is switched on by setting the initial parameter turbulent_inflow = .TRUE..

The turbulent signal A'(y,z) to be imposed at the left inflow boundary is taken from the same simulation at a fixed distance xr from the inflow (given by parameter recycling_width): A'(y,z) = A(xr,y,z) - A(z), where A(z) is the horizontal average between the inflow boundary and the recycling plane. The turbulent quantity A'(y,z) is then added to a mean inflow horizontal average from this precursor run is used as the mean inflow profile for the main run, the wall-normal velocity component must point into the domain at every grid point and its magnitude should be large enough in order to guarantee an inflow even if a turbulence signal is added.

• Since the main run requires  ...
• The into the domain at every grid point and its magnitude should be large enough in order to guarantee an inflow even if a turbulence signal is added.
• The main run requires from the precursor run the mean profiles to be used at the inflow. For this, the horizontally and temporally averaged mean profiles as provided with the standard PALM output are used. The user has to set parameters dt_data_output_pr, averaging_interval, etc. for the precursor run appropriately, so that an output is done at the end of the precursor run. The profile information is then contained in the restart (binary) file created at the end of the precursor run and can be used by the main run. It is very important that the mean profiles at the end of the precursor run are in a stationary or quasi-stationary state, because otherwise it may not be justified to use them as constant profiles at the inflow. Also, turbulence at the end of the precursor run should be fully developed. Otherwise, the main run would need an additional spinup-time at the beginning to get the turbulence to its final stage.
• The main run has to read the binary data from the precursor run ....     set bc_lr = 'dirichlet/radiation' ...
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