Radiation and convection
The basis for this example is a simple roof structure consisting of a wooden panel, insulation and an aluminium outer layer. The internal temperature on the wood surface is kept constant. The outside ambient temperature is also constant but lower than the inside temperature. Five different roof sections are used to demonstrate different definitions for convection and radiation boundary conditions on the surface of the aluminium layer. A transient thermal calculation is carried out.
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Radiation and convection
The basis for this example is a simple roof structure consisting of a wooden panel, insulation and an aluminium outer layer. The internal temperature on the wood surface is kept constant. The outside ambient temperature is also constant but lower than the inside temperature. Five different roof sections are used to demonstrate different definitions for convection and radiation boundary conditions on the surface of the aluminium layer. A transient thermal calculation is carried out.
*BOUNDARY_CONVECTION_SET *BOUNDARY_RADIATION_SET *CONTROL_SOLUTION *CONTROL_TERMINATION *CONTROL_THERMAL_NONLINEAR *CONTROL_THERMAL_SOLVER *CONTROL_THERMAL_TIMESTEP *DATABASE_BINARY_D3PLOT *DATABASE_TPRINT *DEFINE_CURVE *DEFINE_FUNCTION *ELEMENT_SOLID *END *INCLUDE *INITIAL_TEMPERATURE_SET *KEYWORD *MAT_THERMAL_ISOTROPIC *NODE *PART *SECTION_SOLID *SET_NODE_LIST_TITLE *SET_SEGMENT_TITLE *TITLE
*KEYWORD
$
$=============================CONTROL DEFINITIONS ==============================
$
*TITLE
transient heat transfer through an insulated aluminium roof
*CONTROL_SOLUTION
$ thermal only
$ soln nlq isnan lcint lcacc ncdcf
1
*CONTROL_THERMAL_SOLVER
$ transient thermal analysis
$ atype ptype solver cgtol gpt eqheat fwork sbc
1 1 11
$ msglvl maxitr abstol reltol omega tsf
*CONTROL_THERMAL_TIMESTEP
$ ts tip its tmin tmax dtemp tscp lcts
1 1.0 60 30.0 3600.0
*CONTROL_THERMAL_NONLINEAR
$ refmax tol dcp lumpbc thlstl nlthpr phchpn
*CONTROL_TERMINATION
$ endtim endcyc dtmin endeng endmas nosol
288000.0
$
$================================ OUTPUTDATA ===================================
$
*DATABASE_BINARY_D3PLOT
$ dt
300.0
*DATABASE_GLSTAT
$ dt
300.0
*DATABASE_MATSUM
$ dt
300.0
*DATABASE_TPRINT
$ dt
60.0
$
$============================== PART DEFINITIONS ===============================
$
*PART
$ title
wood_panel
$ pid secid mid eosid hgid grav adpopt tmid
1 1 0 0 0 0 0 1
*PART
$ title
insulation
$ pid secid mid eosid hgid grav adpopt tmid
2 1 0 0 0 0 0 2
*PART
$ title
aluminium_sheet
$ pid secid mid eosid hgid grav adpopt tmid
3 1 0 0 0 0 0 3
$
$============================= SECTION PROPERTIES ==============================
$
*SECTION_SOLID
$ secid elform
1 1
$
$======================== THERMAL MATERIAL PROPERTIES ==========================
$
*MAT_THERMAL_ISOTROPIC
$ wood_panel
$ tmid tro tgrlc tgmult tlat hlat
1 6.5e-10
$ hc tc
1.7e9 0.12
*MAT_THERMAL_ISOTROPIC
$ insulation
$ tmid tro tgrlc tgmult tlat hlat
2 1.0e-10
$ hc tc
9.0e8 0.04
*MAT_THERMAL_ISOTROPIC
$ aluminium_sheet
$ tmid tro tgrlc tgmult tlat hlat
3 2.7e-9
$ hc tc
8.97e8 236.0
$
$=======================NODE/ELEMENT/SET/SEGMENT DEFINTIONS ====================
$
*INCLUDE
02_insulated_aluminium_roof_parts.k
*SET_NODE_LIST_TITLE
inside
$ sid da1 da2 da3 da4 solver
1 0.0 0.0 0.0 0.0MECH
$ nid1 nid2 nid3 nid4 nid5 nid6 nid7 nid8
2 35 34 1 3 36 68 67
... ... ... ... ... ... ... ...
*SET_SEGMENT_TITLE
outside_boundary_convection
$ sid da1 da2 da3 da4 solver
1 0.0 0.0 0.0 0.0MECH
$ n1 n2 n3 n4 a1 a2 a3 a4
144 166 167 145 0.0 0.0 0.0 0.0
145 167 168 146 0.0 0.0 0.0 0.0
166 188 189 167 0.0 0.0 0.0 0.0
167 189 190 168 0.0 0.0 0.0 0.0
*SET_SEGMENT_TITLE
outside_boundary_radiation
$ sid da1 da2 da3 da4 solver
2 0.0 0.0 0.0 0.0MECH
$ n1 n2 n3 n4 a1 a2 a3 a4
1044 1050 1051 1045 0.0 0.0 0.0 0.0
... ... ... ... ... ... ... ...
*SET_SEGMENT_TITLE
outside_boundary_rad_substituted_with_conv_curve
$ sid da1 da2 da3 da4 solver
3 0.0 0.0 0.0 0.0MECH
$ n1 n2 n3 n4 a1 a2 a3 a4
1305 1311 1312 1306 0.0 0.0 0.0 0.0
... ... ... ... ... ... ... ...
*SET_SEGMENT_TITLE
outside_boundary_rad_substituted_with_conv_func
$ sid da1 da2 da3 da4 solver
4 0.0 0.0 0.0 0.0MECH
$ n1 n2 n3 n4 a1 a2 a3 a4
1566 1572 1573 1567 0.0 0.0 0.0 0.0
... ... ... ... ... ... ... ...
*SET_SEGMENT_TITLE
outside_boundary_convection_and_radiation
$ sid da1 da2 da3 da4 solver
5 0.0 0.0 0.0 0.0MECH
$ n1 n2 n3 n4 a1 a2 a3 a4
1827 1833 1834 1828 0.0 0.0 0.0 0.0
... ... ... ... ... ... ... ...
$
$==================== THERMAL BOUNDARY and INITIAL CONDITIONS ==================
$
*INITIAL_TEMPERATURE_SET
$ nid/sid temp loc
0 293.15
*BOUNDARY_CONVECTION_SET
$ convection boundary on outerside of the aluminum sheet "column 1"
$ ssid
1
$ hlcid hmult tlcid tmult loc
0 0.01 0 273.15
*BOUNDARY_RADIATION_SET
$ convection boundary on outerside of the aluminum sheet "column 2"
$ ssid type
2 1
$ flcid fmult tlcid tmult loc
03.4022E-11 0 273.15
*BOUNDARY_CONVECTION_SET
$ convection boundary on outerside of the aluminum sheet "column 3"
$ which substitutes radiation by defining hrad trough a curve
$ ssid
3
$ hlcid hmult tlcid tmult loc
-101 1 0 273.15
*BOUNDARY_CONVECTION_SET
$ convection boundary on outerside of the aluminum sheet "column 4"
$ which substitutes radiation by defining hrad trough a function
$ ssid
4
$ hlcid hmult tlcid tmult loc
201 1 0 273.15
*BOUNDARY_CONVECTION_SET
$ convection boundary on outerside of the aluminum sheet "column 5"
$ ssid
5
$ hlcid hmult tlcid tmult loc
0 0.01 0 273.15
*BOUNDARY_RADIATION_SET
$ convection boundary on outerside of the aluminum sheet "column 5"
$ ssid type
5 1
$ flcid fmult tlcid tmult loc
03.4022E-11 0 273.15
*BOUNDARY_TEMPERATURE_SET
$ temperature inside
$ nid/sid tlcid tmult loc tdeath tbirth
1 0 293.15
*DEFINE_FUNCTION
$ hrad as a function of temperature in K, hrad is used to calculate heat
$ convection, which substitutes radiation.
$ fid heading
201 hrad=f(T,Tinf,emis,sbconst)
float func_hrad(float x,float y,float z,float vx,float vy,float vz,float temp,
float tinf,float time)
{
float hrad;
float emissivity=0.6;
float sb=5.6704E-11;
hrad=emissivity*sb*(temp+tinf)*((temp*temp)+(tinf*tinf));
return(hrad);
}
*DEFINE_CURVE
$ hrad as a function of temperature in K, hrad is used to calculate heat
$ convection, which substitutes radiation
$ lcid sidr sfa sfo offa offo dattyp
101 0 1 1 0 0 0
$ Tfilm , hrad
2.6157500E+02,2.4404124E-03
...,...
...
$
*END
