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25<h3 style="line-height: 100%;">3.9 Setup for turbulent inflow</h3>
27<p style="line-height: 100%;">Starting from version 3.5
28PALM includes a so-called turbulence recycling method which allows a
29turbulent inflow with non-cyclic horizontal boundary conditions. The
30method follows the one described by Lund et al. (1998, J. Comp. Phys., <span style="font-weight: bold;">140</span>, 233-258), modified by Kataoka and Mizuno (2002, Wind and Structures, <span style="font-weight: bold;">5</span>, 379-392). The method is switched on by setting the initial parameter <a href="chapter_4.1.html#turbulent_inflow">turbulent_inflow</a> = <span style="font-style: italic;">.TRUE.</span>.</p><p style="line-height: 100%;">The turbulent signal A'(y,z) to be imposed at the left inflow boundary is taken from the same simulation at a fixed distance x<sub>r</sub> from the inflow (given by parameter <a href="chapter_4.1.html#recycling_width">recycling_width</a>): A'(y,z) = A(x<sub>r</sub>,y,z) - <span style="font-weight: bold;">A(z)</span>, where <span style="font-weight: bold;">A(z)</span>
31is the horizontal average between the inflow boundary and the recycling
32plane. The turbulent quantity A'(y,z) is then added to a mean inflow
33profile a(z) which is the horizontal (and temporal) average as
34calculated from a precursor run. This is done after each timestep.</p><p style="line-height: 100%; font-weight: bold;">So far (09/16/08), a turbulent signal is imposed to all prognostic variables except humidity (passive scalar) and salinity!</p><p style="line-height: 100%;">In
35order to avoid a continous growth of the turbulent layer with time, the
36height up to which turbulence is recycled is limited by parameter <a href="chapter_4.1.html#inflow_damping_height">inflow_damping_height</a>. By default, this height is calculated and taken from the precursor run. </p>The following tries to give a short recipe about how to create a proper setup for using the turbulence recycling method:<br><br><ul><li>A
37precursor run with cyclic horizontal boundary conditions has to be
38carried out in order to create a (quasi-) stationary state. Since the
39horizontal average from this precursor run is used as the mean inflow
40profile for the main run, <span style="font-weight: bold;">the
41wall-normal velocity component must point
42into the domain at every grid point and its magnitude should be large
43enough in order to guarantee an inflow even if a turbulence signal is
45main run requires&nbsp;from the precursor run&nbsp;the mean profiles to
46be used at the inflow. For this, the horizontally and temporally
47averaged mean profiles as provided with the standard PALM output are
48used. The user has to set parameters <a href="chapter_4.2.html#dt_data_output_pr">dt_data_output_pr</a>, <a href="chapter_4.2.html#averaging_interval">averaging_interval</a>,
49etc. for the precursor run appropriately, so that an output is done <span style="font-weight: bold;">at
50the end</span> of the precursor run. The profile information is then contained
51in the restart (binary) file created at the end of the precursor run
52and can be used by the main run. <span style="font-weight: bold;">It is very important that the mean profiles at the end of the precursor run are in a stationary or quasi-stationary state</span>, because otherwise it may not be justified to use them as constant profiles at the inflow. <span style="font-weight: bold;">Also, turbulence at the end of the precursor run should be fully developed. </span>Otherwise, the main run would need an additional spinup-time at the beginning to get the turbulence to its final stage.<br></li><li>In order to read the binary data from the precursor run, parameter <a href="chapter_4.1.html#initializing_actions">initializing_actions</a> = <span style="font-style: italic;">'cyclic_fill'</span> has to be set in the main run. &nbsp; .... &nbsp;
53&nbsp; set bc_lr = 'dirichlet/radiation' ... &nbsp;
54conserve_volume_flow = .TRUE. ? ....</li><li>The main run allows to use a larger domain along x and y than in the precursor run ...</li><li>Recycling width should be equal to the domain size of the precursor run (or larger?)</li></ul><pre style="line-height: 100%;"><font style="font-size: 10pt;" size="2">#</font><br><font style="font-size: 10pt;" size="2">RUN_CONTROL<span style="font-weight: bold;">_O</span></font><font style="font-size: 10pt;" size="2"> out:loc:tr d3<span style="font-weight: bold;">o</span># ~/palm/current_version/JOBS/$fname/MONITORING <span style="font-weight: bold;">_</span></font><font style="font-size: 10pt;" size="2"><span style="font-weight: bold;">o</span>_</font><font style="font-size: 10pt;" size="2">rc</font><br><font style="font-size: 10pt;" size="2">HEADER</font><font style="font-size: 10pt;" size="2"><span style="font-weight: bold;">_O</span> out:loc:tr d3<span style="font-weight: bold;">o</span># ~/palm/current_version/JOBS/$fname/MONITORING <span style="font-weight: bold;">_</span></font><font style="font-size: 10pt;" size="2"><span style="font-weight: bold;">o</span>_</font><font style="font-size: 10pt;" size="2">header</font><br><font style="font-size: 10pt;" size="2">PLOT1D_PAR<span style="font-weight: bold;">_O</span></font><font style="font-size: 10pt;" size="2"> out:loc:tr pr<span style="font-weight: bold;">o</span># ~/palm/current_version/JOBS/$fname/OUTPUT <span style="font-weight: bold;">_</span></font><font style="font-size: 10pt;" size="2"><span style="font-weight: bold;">o</span>_</font><font style="font-size: 10pt;" size="2">pr_par</font><br><font style="font-size: 10pt;" size="2">PLOT1D_DATA</font><font style="font-size: 10pt;" size="2"><span style="font-weight: bold;">_O</span> out:loc:tr pr<span style="font-weight: bold;">o</span># ~/palm/current_version/JOBS/$fname/OUTPUT <span style="font-weight: bold;">_</span></font><font style="font-size: 10pt;" size="2"><span style="font-weight: bold;">o</span>_</font><font style="font-size: 10pt;" size="2">pr_in</font><br></pre><br><hr>
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