Changes between Version 16 and Version 17 of doc/app/examples/turbinf
- Timestamp:
- Nov 22, 2018 2:23:25 PM (7 years ago)
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doc/app/examples/turbinf
v16 v17 1 1 = Setup for turbulent inflow = 2 2 3 Starting from version 3.5 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), modified by Kataoka and Mizuno (2002). The method is switched on by setting the initial parameter [../../inipar#turbulent_inflow turbulent_inflow] = ''.TRUE.''.3 Starting from version 3.5 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 [#lund1988 Lund et al. (1998)], modified by [kataoka2002 Kataoka and Mizuno (2002)]. The method is switched on by setting the initial parameter [../../inipar#turbulent_inflow turbulent_inflow] = ''.TRUE.''. 4 4 5 5 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,,r,, from the inflow (given by parameter [../../inipar#recycling_width recycling_width]): A'(y,z) = A(x,,r,,,y,z) - '''A(x,,r,,,z)''', where '''A(x,,r,,,z)''' is the line average along y. The turbulent quantity A'(y,z) is then added to a mean inflow profile a(z) which is the horizontal (and temporal) average as calculated from a precursor run. This is done after each timestep. … … 7 7 In order to avoid a continous growth of the turbulent layer with time, the height up to which turbulence is recycled is limited by parameter [../../inipar#inflow_damping_height inflow_damping_height]. By default, this height is equal to the the height of the boundary layer z_i calculated by the precursor run. In the case of a strictly neutral flow you have to set the parameter [../../inipar#inflow_damping_height inflow_damping_height] because the value of z_i calculated by the precursor run is zero. 8 8 9 '''So far, a turbulent inflow is realized from the left (west) side only ( 05/04/16)! '''9 '''So far, a turbulent inflow is realized from the left (west) side only (2016/04/05)! ''' 10 10 11 11 The following tries to give a short recipe about how to create a proper setup for using the turbulence recycling method: … … 33 33 Set [../../inipar#turbulent_inflow turbulent_inflow] = .T. . 34 34 35 Define the position of the recycling plane via [../../inipar#recycling_width recycling_width]. The distance between the inflow and the recycling plane should be large enough to allow for a sufficient advancement of the turbulent eddies (should be somehow correlated with the eddy turnover time). Otherwise, almost the same eddies will be recycled again and again, which will distort the turbulence statistics. Typically, the recycling width will be similar or equal to the domain size of the precursor run.35 Define the position of the recycling plane via [../../inipar#recycling_width recycling_width]. The distance between the inflow and the recycling plane should be large enough to allow for a sufficient advancement of the turbulent eddies (should be somehow correlated with the eddy turnover time). Otherwise, almost the same eddies will be recycled again and again, which will distort the turbulence statistics. Typically, the recycling width will be about the same size as the domain size of the precursor run. It is, however, recommended that both sizes do not exactly match to prevent the development of fixed-sized structures. 36 36 37 37 A damping layer for the turbulence signal can be set at top of the domain via [../../inipar#inflow_damping_height inflow_damping_height] and [../../inipar#inflow_damping_width inflow_damping_width]. Inside the damping layer the turbulence signal is linearly damped to 0%. For [../../inipar#inflow_damping_height inflow_damping_height] the boundary layer height from the precursor run should be used. 38 38 39 The recycled turbulence, which is mapped from the recycling plane to the inflow boundary, can be shifted in y direction. This y-shift reduces persistent streaks that may occur within the recycling domain. To use the y-shift [../../inipar#recycling_yshift recycling_yshift] = .T. needs to be set. The distance of the y-shift is INT([../../d3par#npey npey] / 2), which is in most cases the best distance for effectively reducing streaks in the recycling domain. 39 The recycled turbulence, which is mapped from the recycling plane to the inflow boundary, can be shifted in y direction. This y-shift reduces persistent streaks that may occur within the recycling domain. To use the y-shift [../../inipar#recycling_yshift recycling_yshift] = .T. needs to be set. The distance of the y-shift is INT([../../d3par#npey npey] / 2), which is in most cases the best distance for effectively reducing streaks in the recycling domain. 40 40 41 * When starting the main run, [wiki:doc/app/palmrun palmrun] must be told to provide the binary data of the restart run. For this, first the list of input-files in ''.palm.iofiles'' must be modified. In line 42 {{{ 43 BININ in:loc:flpe d3r $base_data/$run_identifier/RESTART _d3d 44 }}} 45 an additional flag, e.g. ''cycfill'' has to be added in the third column: 46 {{{ 47 BININ in:loc:flpe d3r:cycfill $base_data/$run_identifier/RESTART _d3d 48 }}} 49 This flag has to be added to the run control list of the palmrun command (option {{{-a}}}, see job control with [wiki:doc/app/palmrun palmrun]) when starting the main run as well. 41 * When starting the main run, [wiki:doc/app/palmrun palmrun] must be told to provide the binary data of the restart run which is done by adding 'rec' to the activation-string list of the palmrun command (option {{{-a}}}, see job control with [wiki:doc/app/palmrun palmrun]). 50 42 51 43 === References === 52 44 53 * ''' Lund, T. S., X. Wu and K. D. Squires, 1998:''' Generation of turbulent inflow data for spatially-developing boundary layer simulations. ''J. Comput. Phys.'', '''140''', 233-258.45 * '''[=#lund1988 Lund, T. S.], X. Wu and K. D. Squires, 1998:''' Generation of turbulent inflow data for spatially-developing boundary layer simulations. ''J. Comput. Phys.'', '''140''', 233-258. 54 46 55 * ''' Kataoka, H.and M. Mizuno, 2002:''' Numerical flow computation around aeroelastic 3D square cylinder using inflow turbulence. ''Wind Struct.'', '''5''', 379-392.47 * '''[=#kataoka2002 Kataoka, H.] and M. Mizuno, 2002:''' Numerical flow computation around aeroelastic 3D square cylinder using inflow turbulence. ''Wind Struct.'', '''5''', 379-392.
