radiation_cooling.mac

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!
! Filename: radiation_cooling.mac, ANSYS APDL script
! by <vladimir.kolchuzhin@ieee.org>
!
! Issue: 
! 	A block is initially at a temperature Tb. 
! 	Body loses heat by radiation from surfaces to surroundings at Tamb.
! 	The temperature Tb of the box at the time_end is simulated.
!
! Ref.: ANSYS MEDIA REL. 11.0 (10/27/2006) REF. VERIF. MANUAL: REL. 11.0 
!	VERIFY,VM192, COOLING OF A BILLET BY RADIATION
!	THERMAL RADIATION HEAT TRANSFER, SIEGEL AND HOWELL, 2ND EDITION,
!	PG. 229, PROBLEM NO. 2
!
! Rev.:	
!	2022-04-10 Munich VM192r.mac		tested
!	2026-06-10 Munich radiation_cooling.mac release
!
!==========================================================================!
!
!                 ^ ^ ^ ^ ^ ^ ^ ^
!                 | | | | | | | |
!		 o---------------o 
!	     <-- |               |-->
!            <-- |      o Tb     |-->  P=sigma*area*T^4
!            <-- |               |-->
!		 o---------------o
!                 | | | | | | | |   * Tamb
!                 v v v v v v v v
!
!          ASCII-Schematic of the problem: small copper block
!==========================================================================!
!
!
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FINISH $/CLEAR $/CONTOUR,1,128
/VUP,,Z

/TITLE, transient heat transfer analysis: small copper block cooling by radiation
project_name='radiation_cooling'

!--------------------------------------------------------------------------!

/PREP7

mm=1e-3		!
um=1e-6		!

PI=2*ASIN(1)	! PI constant
SB=5.67037E-8	! STEFAN-BOLTZMANN constant W/(m^2K^4)

!-------------------------! geometry parametrs !---------------------------!

a= 10.0*mm		! block length
b= 10.0*mm		! block  width
c=  1.0*mm		! block thickness

Xa=a*3			! ref point for Tamb

Tb= 1000		! body temperature, K
Tamb=300		! ambient temperature, K


el_size=b/4		! mesh quality: element size

time_end=200		! time end, sec

key_analysis=4		! transient analysis

!--------------------------------------------------------------------------!
!----------------------! Defines elements types !--------------------------!
!--------------------------------------------------------------------------!

ET,1,SOLID70            ! 3-D THERMAL SOLID ELEMENT
ET,2,SURF152,,,,1,1     ! 3-D THERMAL SURFACE EFFECT ELEMENT
KEYOPT,2,9,1            ! radiation option
R,2,1,SB		! form factor = 1, STEFAN-BOLTZMANN constant

!--------------------------------------------------------------------------!
!-------------------! Defines material properties !------------------------!
!--------------------------------------------------------------------------!
EMUNIT,MKS

! thermal material properties:
kth=380				! Cu   thermal conductivity, W/(mK)
rho=8950			! Cu   density, kg/m/m/m
cp=385				! Cu   specific heat capacity C, J/(kgK)
!--------------------------------------------------------------------------!
MP,KXX,1,kth			! thermal conductivity
MP,C,1,cp			! specific heat capacity
MP,DENS,1,rho			! density

MP,EMIS,2,0.8			! black body emissivity
!--------------------------------------------------------------------------!
!-------------------------------! Geometry !-------------------------------!
!--------------------------------------------------------------------------!
BLOCK,-a/2,a/2,-b/2,b/2,-c/2,c/2	! block volume

VSUM

volu=a*b*c
surface_area=2*a*b + 2*a*c + 2*b*c
!--------------------------------------------------------------------------!
!------------------------------! FEA Domain !------------------------------!
!--------------------------------------------------------------------------!
! mesh

SMRT,OFF
 !SMRTSIZE,4		! set smart size meshing level 4 (fine)


ESIZE,el_size
MAT,1 $TYPE,1
VMESH,1			! 3D mesh with SOLID70 element

*GET,Nmax,NODE,,NUM,MAX
*GET,Emax,ELEM,,NUM,MAX

num_node_max=Nmax
XNODE=num_node_max+1

TYPE,2 $REAL,2 $MAT,2
N,XNODE,Xa,Xa,Xa	! define node for radiation
ESURF,XNODE		! generate surface SURF152 elements

!--------------------------------------------------------------------------!
!--------------------! Defines components for BCs !------------------------!
!--------------------------------------------------------------------------!
csys,0
cmsel,all $allsel
eplot
!==========================================================================!

/PNUM,MAT,1 $/NUMBER,1 $EPLOT

 !save,project_name,db,,all

!==========================================================================!
! apply load and BCs

cmsel,all $allsel
!==========================================================================!
!==========================================================================!
!*if,key_analysis,eq,4,then

/solu
antype,transient		! transient heat transfer analysis

SOLCONTROL,0
D,XNODE,TEMP,Tamb		! specify Tamb ambient absolute temperature
TUNIF,Tb			! initial Tb absolute temperature
AUTOTS,ON               
KBC,1				! step ambient temperature in first time step

DELTIM,time_end/100		! initial integration time step: time_end/100
OUTRES,,ALL
OUTPR,NSOL,LAST
TIME,time_end			! transient time span

solve

!*endif
!==========================================================================!
!==========================================================================!
/post1
set,last

ples,heat
plns,temp
allsel

FSUM,HEAT	! sums the nodal force and moment contributions of elements

 !*GET,Q,FSUM,0,ITEM,HEAT	! [HEAT]=W

!==========================================================================!
/post26

NSOL,2,1,TEMP,,TEMP	! temperature history
!PRVAR,2

/AXLAB,X,'Time, s'
/AXLAB,Y,'Temperature, K'
PLVAR,2
!==========================================================================!
!==========================================================================!