- boundaryThe list of boundary IDs from the mesh where this object applies
C++ Type:std::vector<BoundaryName>
Unit:(no unit assumed)
Controllable:No
Description:The list of boundary IDs from the mesh where this object applies
UnobstructedPlanarViewFactor
Description
UnobstructedPlanarViewFactor computes the view factors between n planar sides in radiative heat exchange. These sides need to be such that they do not obstruct each other. This is in particular true if the sides fully enclose a convex volume. This is the intended purpose of this UserObject.
View factors from side to side are computed via a double loop over side elements and the quadrature points defined on them. View factors are computed by numerically evaluating:
where is the distance between two points on the surfaces and and and are the angles that the line connecting these two points make with the normals at surface one and two, respectively.
In two-dimensional geometries, a different formula is evaluated. It is derived from the original formula by considering a geometry that is extruded from to along the -axis. We denote by the distance between two points on surface one and two projected onto the plane orthogonal to the -axis. The line projected on this plane makes angles and with the normals at surfaces one and two, respectively. Note that the normals have no component into the -direction. The following relationships hold:
The view factor is then given by:
The integral in brackets evaluates to:
The view factors in two-dimensional geometry are consequently given by:
View factors should satisfy:
This can be checked by setting the parameter view_factor_tol and it can be enforced via normalization by setting the parameter normalize_view_factor.
It is stressed that this UserObject may give wrong results if obstruction is present
Example Input syntax
[GlobalParams]
view_factor_object_name = unobstructed_vf
[]
[Mesh]
type = GeneratedMesh
dim = 2
xmin = 0
xmax = 2
ymin = 0
ymax = 1
nx = 2
ny = 2
[]
[UserObjects]
active = 'unobstructed_vf'
[unobstructed_vf]
type = UnobstructedPlanarViewFactor
boundary = 'top left right bottom'
execute_on = INITIAL
[]
[vf_study]
type = ViewFactorRayStudy
execute_on = initial
boundary = 'left right bottom top'
face_order = TENTH
polar_quad_order = 80
[]
[rt_vf]
type = RayTracingViewFactor
boundary = 'left right bottom top'
execute_on = INITIAL
normalize_view_factor = false
ray_study_name = vf_study
[]
[]
##
## Reference: bottom -> left/right = 0.19098
## bottom -> top = 0.61803
## Result at spatial order 20, angular order 200 & -r2
## bottom -> left/right = 0.1911
## bottom -> top = 0.6177
##
## For convenience, the "view_factor_object_name" for these
## PPs are set in global params for switching between methods
##
[Postprocessors]
[left_right]
type = ViewFactorPP
from_boundary = left
to_boundary = right
[]
[left_top]
type = ViewFactorPP
from_boundary = left
to_boundary = top
[]
[left_bottom]
type = ViewFactorPP
from_boundary = left
to_boundary = bottom
[../]
[bottom_left]
type = ViewFactorPP
from_boundary = bottom
to_boundary = left
[]
[bottom_right]
type = ViewFactorPP
from_boundary = bottom
to_boundary = right
[]
[bottom_top]
type = ViewFactorPP
from_boundary = bottom
to_boundary = top
[]
[]
[Problem]
solve = false
[]
[Executioner]
type = Steady
[Quadrature] # higher order quadrature for unobstructed
order = SECOND
[]
[]
[Outputs]
csv = true
[]
Input Parameters
- execute_onTIMESTEP_ENDThe list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
Default:TIMESTEP_END
C++ Type:ExecFlagEnum
Unit:(no unit assumed)
Controllable:No
Description:The list of flag(s) indicating when this object should be executed. For a description of each flag, see https://mooseframework.inl.gov/source/interfaces/SetupInterface.html.
- normalize_view_factorTrueDetermines if view factors are normalized to sum to one (consistent with their definition).
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Determines if view factors are normalized to sum to one (consistent with their definition).
- print_view_factor_infoFalseFlag to print information about computed view factors.
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Flag to print information about computed view factors.
- prop_getter_suffixAn optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
C++ Type:MaterialPropertyName
Unit:(no unit assumed)
Controllable:No
Description:An optional suffix parameter that can be appended to any attempt to retrieve/get material properties. The suffix will be prepended with a '_' character.
- use_interpolated_stateFalseFor the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:For the old and older state use projected material properties interpolated at the quadrature points. To set up projection use the ProjectedStatefulMaterialStorageAction.
- view_factor_tol1.79769e+308Tolerance for checking view factors. Default is to allow everything.
Default:1.79769e+308
C++ Type:double
Unit:(no unit assumed)
Controllable:No
Description:Tolerance for checking view factors. Default is to allow everything.
Optional Parameters
- allow_duplicate_execution_on_initialFalseIn the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:In the case where this UserObject is depended upon by an initial condition, allow it to be executed twice during the initial setup (once before the IC and again after mesh adaptivity (if applicable).
- control_tagsAdds user-defined labels for accessing object parameters via control logic.
C++ Type:std::vector<std::string>
Unit:(no unit assumed)
Controllable:No
Description:Adds user-defined labels for accessing object parameters via control logic.
- enableTrueSet the enabled status of the MooseObject.
Default:True
C++ Type:bool
Unit:(no unit assumed)
Controllable:Yes
Description:Set the enabled status of the MooseObject.
- execution_order_group0Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
Default:0
C++ Type:int
Unit:(no unit assumed)
Controllable:No
Description:Execution order groups are executed in increasing order (e.g., the lowest number is executed first). Note that negative group numbers may be used to execute groups before the default (0) group. Please refer to the user object documentation for ordering of user object execution within a group.
- force_postauxFalseForces the UserObject to be executed in POSTAUX
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Forces the UserObject to be executed in POSTAUX
- force_preauxFalseForces the UserObject to be executed in PREAUX
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Forces the UserObject to be executed in PREAUX
- force_preicFalseForces the UserObject to be executed in PREIC during initial setup
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Forces the UserObject to be executed in PREIC during initial setup
- use_displaced_meshFalseWhether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.
Default:False
C++ Type:bool
Unit:(no unit assumed)
Controllable:No
Description:Whether or not this object should use the displaced mesh for computation. Note that in the case this is true but no displacements are provided in the Mesh block the undisplaced mesh will still be used.