This section describes how to do a steady-state thermal radiation analysis of a conical fin using the radiosity solver method by issuing a sequence of commands, either while running in batch mode or by issuing the commands manually during an interactive session.
In this example, two circular annulus radiating to each other are considered. The outer surface of the inner annulus has an emissivity of 0.9. Its inner surface is maintained at a temperature of 1500°F. The inner surface of the outer annulus has an emissivity of 0.7, and its outer surface is maintained at a temperature of 100°F. The space temperature is maintained at 70°F.
The following sequence of commands builds and solves the finite element model. Text preceded by an exclamation mark (!) is comment text.
/TITLE,RADIATION BETWEEN CIRCULAR ANNULUS ! Example for 2D radiation analysis using the radiosity method /PREP7 CYL4,0,0,.5,0,.25,180 ! Circular annulus 1 CYL4,0.2,0,1,0,.75,180 ! Circular annulus 2 ET,1,PLANE55 ! 2D thermal element LSEL,S,LINE,,1 SFL,ALL,RDSF,.9, ,1, ! Radiation boundary condition on inner annulus LSEL,S,LINE,,7 SFL,ALL,RDSF,.7, ,1, ! Radiation boundary condition on outer annulus LSEL,S,LINE,,3 DL,ALL, ,TEMP,1500,1 ! Temperature on inner annulus LSEL,S,LINE,,5 DL,ALL, ,TEMP,100,1 ! Temperature on outer annulus ALLSEL STEF,0.119E-10 ! Stefan-Boltzmann constant TOFFST,460 ! Temperature offset RADOPT,,0.01,0, ! Radiosity solver options SPCTEMP,1,70 ! Space temperature for enclosure 1 V2DOPT,0.0,0,0, ! 2D view factor options ESIZE,0.05, AMESH,ALL MP,KXX,1,.1 ! Thermal Conductivity FINISH /SOLU TIME,1 DELTIM,.5,.1,1 NEQIT,1000 SOLVE FINISH /POST1 ASEL,S,AREA,,1 NSLA,S,1 PRNSOL,TEMP FINISH