ABL Forcing¶

abl_forcing
¶ abl_forcing
allows the user to specify desired velocities and temperatures at different heights. These velocities and temperatures are enforced through the use of source in the momentum and enthalpy equations. Theabl_forcing
option needs to be specified in themomentum
and/orenthalpy
source blocks: source_terms: momentum: abl_forcing enthalpy: abl_forcing
This option allows the code to implement source terms in the momentum and/or enthalpy equations. A sample section is shown below
abl_forcing: search_method: stk_kdtree search_tolerance: 0.0001 search_expansion_factor: 1.5 output_frequency: 1 from_target_part: [fluid_part] momentum: type: computed relaxation_factor: 1.0 heights: [250.0, 500.0, 750.0] target_part_format: "zplane_%06.1f" # The velocities at each plane # Each list include a time and the velocities for each plane # Notice that the total number of elements in each list will be # number of planes + 1 velocity_x:  [0.0, 10.0, 5.0, 15.0]  [100000.0, 10.0, 5.0, 15.0] velocity_y:  [0.0, 0.0, 0.0, 0.0]  [100000.0, 0.0, 0.0, 0.0] velocity_z:  [0.0, 0.0, 0.0, 0.0]  [100000.0, 0.0, 0.0, 0.0] temperature: type: computed relaxation_factor: 1.0 heights: [250.0, 500.0, 750.0] target_part_format: "zplane_%06.1f" temperature:  [0.0, 300.0, 280.0, 310.0]  [100000.0, 300.0, 280.0, 310.0]
Note
The variables in the abl_forcing
subsection are
prefixed with abl_forcing.name
but only the variable
name after the period should appear in the input file.

abl_forcing.search_method
¶ This specifies the search method algorithm within the stk framework. The default option stk_kdtree is recommended.

abl_forcing.search_tolerance
¶ This is the tolerance specified for the search_method algorithm. A default value of 0.0001 is recommended.

abl_forcing.search_expansion_factor
¶ This option is related to the stk search algorithm. A value of 1.5 is recommended.

abl_forcing.output_frequency
¶ This is the frequency at which the source term is written to the output value. A value of 1 means the source term will be written to the output file every timestep.
Note
There are now two options in the following inputs.
The can be momentum
and/or temperature
.

abl_forcing.momentum.computed
¶ This option allows the user to choose if a momentum source is computed from a desired velocity (
computed
) or if a user defined source term is directly applied into the momentum equation (user_defined
).

abl_forcing.momentum.relaxation_factor
¶ This is a relaxation factor which can be used to under/overrelax the momentum source term. The default value is 1.

abl_forcing.momentum.heights
¶ This is a list containing the planes at which the forcing should be implemented. Each input is the height for that plane. This is the naming convention in the mesh file.

abl_forcing.momentum.target_part_format
¶ This is the format in which the planes are saved in the mesh file.

abl_forcing.momentum.velocity_x
¶ A set of lists containing the time in the first element, followed by the desired velocity at each plane in the \(x\) direction.

abl_forcing.momentum.velocity_y
¶ A set of lists containing the time in the first element, followed by the desired velocity at each plane in the \(y\) direction.

abl_forcing.momentum.velocity_z
¶ A set of lists containing the time in the first element, followed by the desired velocity at each plane in the \(z\) direction.
Note
The temperature has the same inputs as the momentum source
(abl_forcing.temperature.type
,
abl_forcing.temperature.relaxation_factor
,
abl_forcing.temperature.heights
, and
abl_forcing.temperature.target_part_format
)
which take the same options.

abl_forcing.temperature.temperature
¶ A set of lists containing the time in the first element, followed by the desired temperature at each plane.