关于热辐射对称模型的问题，rsymm的使用

ozeanluft

本人做了个3D热辐射的模型，是一对同心的圆柱(在内)和圆环（在外），取了其中的1/4进行分析，在加对称的时候，使用了dsym,symm,x,0和dsym,symm,y,0来约束了几何形状，然后加入了RSYMM, define, 0, x,, off和RSYMM, define, 0, y,, off来加上垂直于x和y轴的辐射对称面，可是计算出来的结果和没加这两个rsymm约束的一样，也就是这两个热辐射对称面完全没有起到作用，在此想问问大家如何才能正确的定义热辐射的对称面，


在ansys help里面有个热辐射对称的例子，用到了rsymm，那是个2D的例子:
/title,Radiation Problem Using Radiosity Surface Elements
/prep7
w     = 1
thick = 1
h     = 0.06
!
tempoff = 270             ! Conversion to absolute temp
sbc     = 5.67e-8         ! Stefan-Boltzman constant
T1      = 1000
T2      = 500
emiss1  = 0.5
emiss2  = 0.25
!
rectng,-0.5*w,,0.5*h,0.5*h+thick
rectng,-0.5*w,,-0.5*h,-0.5*h-thick
!
et,1,55
mp,kxx,1,1
mshape,0,2D
mshkey,1
esize,0.125
lesize,all,,,,-1.5
amesh,all
!
! Specify temp/emissivity/rdsf on plane 1
!
nsel,s,loc,y,0.5*h
sf,all,rdsf,emiss1,1   
d,all,temp,T1   
!
! Specify temp/emissivity/rdsf on plane 2
!
nsel,s,loc,y,-0.5*h
sf,all,rdsf,emiss2,1  
d,all,temp,T2   
nsel,all
allsel                 ! Select PLANE55 nodes/elements for RSURF command

!
! Specify radiation options
!
toffst,tempoff
stef,sbc      
radopt,1.0,1.0e-5,0,10000,,0.9
v2dopt,0,0,0,400
spctemp,1,0
vfopt,new,,,,asci
fini
/solu

rdec,,0.5              ! Set decimation to 50 percent reduction
rsymm,,0,x             ! Specify reflection about the x-axis
rsurf                  ! Generate SURF251 elements and store in database

nlist                  ! Includes SURF251 nodes
elist                  ! Includes SURF251 elements
save
time,1
deltim,1


solve
fini
/post1
set,last
nsel,s,loc,y,0.5*h     ! Select nodes of plane 1 and get nodal reaction
prrsol      
nsel,s,loc,y,-0.5*h    ! Select nodes of plane 2 and get nodal reaction
prrsol      
nsel,all
*get,radnh,RAD,1,nethf ! Get the net outgoing radiant heat flux
                       ! This should equal reaction 1 + reaction 2
*stat

!using nmisc element records to get net heat rate/emissivity/temp/
!enclosure/area/etc.

esel,s,type,,2 !select surf251
etable,elmarea,nmisc,4   ! Get element areas
etable,elmradnf,nmisc,7  ! Get element net outgoing radiant heat flux
smult,elmradnh,elmarea,elmradnf  ! Multiply area*flux, store as heats
etable,elmradnf,erase
ssum                     ! Get net area net heats.
                         ! Net heat should = reaction 1 + reaction 2

!report element centroid & enclosure

etable,elmcenx,nmisc,1   ! Get element centroid x-coord
etable,elmceny,nmisc,2   ! Get element centroid y-coord
etable,elmcenz,nmisc,3   ! Get element centroid z-coord
etable,elmencl,nmisc,18  ! Get element enclosure number
pretab,elmencl,elmcenx,elmceny,elmcenz

!report element avg temp, emiss

etable,elmtemp,nmisc,5   ! Get element average temp
etable,elmemiss,nmisc,6  ! Get element average emissivity
pretab,elmtemp,elmemiss  

!report netheatflux = emit+refl-inci   
                                    
etable,elmradnf,nmisc,7  ! Get element net outgoing radiant heat flux
etable,elmradem,nmisc,8  ! Get element emitted heat flux
etable,elmradre,nmisc,9  ! Get element reflected heat flux
etable,elmradin,nmisc,10 ! Get element radiant heat flux
pretab,elmradnf,elmradem,elmradre,elmradin
fini在这里面，有v2dopt来定义2D view factor对称选项，然后下面有关于radiation decimation的定义，不大懂，然后它用到了surf251单元来进行radiosity method计算，
我没有用surf251，直接用的是3D模型上的surface element，也没有设置view factor对称的问题，不知道rsymm是不是作为3D模型的view factor 对称的定义，

同时在help里面有这么一段说明:
If you issue RSYMM more than once, each command will be processed in the order issued. For example, you could issue the following to turn condensation on, conduct a planar reflection about the global X axis, and then conduct a planar reflection about the global Y axis:
rsym,cond,,,,ON
rsym,,,x
rsym,,,y

这里的condensation到底指什么，

rsym,,,y


感觉对辐射计算的机理非常的不解，请各位大大指点指点把，谢谢！！

ozeanluft

help me!!!

alwvke

二维的我没碰到要用这个命令啊，辐射方向也是对的