SOLAR_RADIATION_SURFACE
Specifies a solar radiation heat flux condition on a surface.
Type
AcuSolve Command
Syntax
SOLAR_RADIATION_SURFACE("name") {parameters...}
Qualifier
User-given name.
Parameters
- shape (enumerated) [no default]
- Shape of the surfaces in this set.
- three_node_triangle or tri3
- Three-node triangle.
- four_node_quad or quad4
- Four-node quadrilateral
- six_node_triangle or tri6
- Six-node triangle.
- element_set or elem_set (string) [no default]
- User-given name of the parent element set.
- surfaces (array) [no default]
- List of element surfaces.
- surface_sets (list) [={}]
- List of surface set names (strings) to use in this command. When using this option, the connectivity, shape, and parent element of the surfaces are provided by the surface set container and it is unnecessary to specify the shape, element_set and surfaces parameters directly to the SOLAR_RADIATION_SURFACE command. This option is used in place of directly specifying these parameters. In the event that both of the surface_sets and surfaces parameters are provided, the full collection of surface elements is read and a warning message is issued. The surface_sets option is the preferred method to specify the surface elements. This option provides support for mixed element topologies and simplifies pre-processing and post-processing.
- side (enumerated) [=default]
- Side of the surface that receives solar heat flux.
- default
- Side is based on the element medium.
- inward
- Side facing into the element.
- outward
- Side facing away from the element.
- both
- Both sides.
- solar_radiation_model (string) [no default]
- User-given name of the solar radiation model.
Description
This command specifies a solar radiation heat flux condition on a set of surfaces (element faces). This condition is coupled to all other solar radiation surfaces, but not to radiation surfaces or radiation element boundary conditions. The SOLAR_RADIATION command provides a detailed description of this coupling.
ELEMENT_SET( "interior" ) {
shape = four_node_tet
medium = fluid
elements = { 1, 8, 3, 4, 9 ;
3, 3, 4, 9, 5 ;
... }
...
}
SOLAR_RADIATION_SURFACE( "wall" ) {
shape = three_node_triangle
element_set = "interior"
surfaces = { 1, 12, 9, 3, 4 ;
3, 52, 5, 3, 4 ; }
side = default
solar_radiation_model = "solar reflectivity"
}
specifies a solar radiation heat flux condition to be applied to the default side of each of two surfaces of the element set "interior" using the solar radiation model "solar reflectivity".
- Element Shape
- Surface Shape
- four_node_tet
- three_node_triangle
- five_node_pyramid
- three_node_triangle
- five_node_pyramid
- four_node_quad
- six_node_wedge
- three_node_triangle
- six_node_wedge
- four_node_quad
- eight_node_brick
- four_node_quad
- ten_node_tet
- six_node_triangle
The surfaces parameter contains the faces of the element set. This parameter is a multi-column array. The number of columns depends on the shape of the surface. For three_node_triangle, this parameter has five columns, corresponding to the element number (of the parent element set), a unique (within this set) surface number, and the three nodes of the element face. For four_node_quad, surfaces has six columns, corresponding to the element number, a surface number, and the four nodes of the element face. For six_node_triangle, surfaces has eight columns, corresponding to the element number, a surface number, and the six nodes of the element face. One row per surface must be given. The three, four, or six nodes of the surface may be in any arbitrary order, since they are reordered internally based on the parent element definition.
1 12 9 3 4
3 52 5 3 4
SOLAR_RADIATION_SURFACE ( "wall" ) {
shape = three_node_triangle
element_set = "interior"
surfaces = Read( "wall.srf" )
...
}
SURFACE_SET( "tri faces" ) {
surfaces = { 1, 1, 1, 2, 4 ;
2, 2, 3, 4, 6 ;
3, 3, 5, 6, 8 ; }
shape = three_node_triangle
volume_set = "tetrahedra"
}
SURFACE_SET( "quad faces" ) {
surfaces = { 1, 1, 1, 2, 4, 9 ;
2, 2, 3, 4, 6, 12 ;
3, 3, 5, 6, 8, 15 ; }
shape = four_node_quad
volume_set = "prisms"
SOLAR_RADIATION_SURFACE ( "wall" ) {
surface_sets = {"tri_faces", "quad_faces"}
...
}
tri faces
quad faces
SOLAR_RADIATION_SURFACE ( "wall" ) {
surface_sets = Read("surface_sets.srfst")
...
}
The mixed topology version of the SOLAR_RADIATION_SURFACE command is preferred. This version provides support for multiple element topologies within a single instance of the command and simplifies pre-processing and post-processing. In the event that both the surface_sets and surfaces parameters are provided in the same instance of the command, the full collection of surface elements is read and a warning message is issued. Although the single and mixed topology formats of the commands can be combined, it is strongly recommended that they are not.
The side parameter specifies which side of the surface is active. If the solar radiation comes from the opposite side then the surface does not interact with this radiation, that is, the surface is completely transparent. An inward side faces towards the interior of its parent element, and an outward side faces away from the element. A value of both means that both the inward and outward sides are active. A default side is chosen based on the medium parameter of the ELEMENT_SET command. For a fluid medium, default is the same as inward, and for solid and shell media, default is the same as outward.
VOLUME_SET("interior"){
shape = eight_node_brick
elements = { 1, 1, 2, 3, 4, 5, 6, 7, 8 ;
... }
}
SURFACE_SET("roof"){
shape = four_node_quad
surfaces = { 1, 1, 1, 2, 3, 4 ;
... }
volume_set = "interior"
}
ELEMENT_SET( "air" ) {
medium = fluid
volume_sets = {"interior"}
...
}
SOLAR_RADIATION_SURFACE( "interior side" ) {
surface_sets = {"roof"}
side = inward
solar_radiation_model = "headliner cloth"
}
SOLAR_RADIATION_SURFACE( "exterior side" ) {
surface_sets = {"roof"}
side = outward
solar_radiation_model = "exterior paint"
}
SOLAR_RADIATION_MODEL( "headliner cloth" ) {
specular_transmissivity = 0.0
diffuse_transmissivity = 0.0
specular_reflectivity = 0.05
diffuse_reflectivity = 0.4
}
SOLAR_RADIATION_MODEL( "exterior paint" ) {
specular_transmissivity = 0.0
diffuse_transmissivity = 0.0
specular_reflectivity = 0.6
diffuse_reflectivity = 0.1
}
The surface of the interior fluid elements that lie against the inside of the roof are split into inward and outward pointing sides. The inward pointing side models the properties of the headliner cloth, and the outward pointing side models the exterior paint on the roof. This avoids directly modeling the roof itself. However, it may be important to do so if the thermal resistance of the roof is significant.
VOLUME_SET("glass"){
shape = eight_node_brick
elements = { 1, 1, 2, 3, 4, 5, 6, 7, 8 ;
... }
}
SURFACE_SET("windshield"){
shape = four_node_quad
surfaces = { 1, 1, 1, 2, 3, 4 ;
... }
volume_set = "glass"
}
ELEMENT_SET( "glass" ) {
medium = solid
volume_sets = {"glass"}
...
}
SOLAR_RADIATION_SURFACE( "both windshield surfaces" ) {
surface_sets = {"glass"}
side = both
solar_radiation_model = "windshield, one surface"
}
SOLAR_RADIATION_MODEL( "windshield, one surface" ) {
specular_transmissivity = 0.9
specular_reflectivity = 0.1
}
SOLAR_RADIATION_SURFACE( "lumped windshield surfaces" ) {
...
side = both
solar_radiation_model = "windshield, both surfaces"
}
SOLAR_RADIATION_MODEL( "windshield, both surfaces" ) {
specular_transmissivity = 0.81
specular_reflectivity = 0.19
}
SOLAR_RADIATION_SURFACE( "both windshield surfaces, cheaper model" ) {
...
side = outward
solar_radiation_model = "windshield, both surfaces"
}
For all three of the above models there would be no solar radiation surfaces on the fluid elements on either side of the windshield. When a fluid element is adjacent to an unmodeled solid wall, such a surface would normally be created and assigned the solar radiation properties of the solid wall, as in the roof example.
All data from all SOLAR_RADIATION_SURFACE commands are preprocessed to form the solar heat flux for each of several given points in time (see the SOLAR_RADIATION command). This data is then interpolated for each time step during the simulation.
Since the solar radiation data is preprocessed, its content is written to disk. Once the problem has run, its values for all solved time steps can be translated to other formats using the AcuTrans program and other post-processing modules; see the AcuSolve Programs Reference Manual for details.