我想计算一根热的水平长条(矩形铜母线)在空气中的自然对流换热情况,在ANSYS Mechanical/Flotran/ LSDYNA Prepost里进行仿真。使用二维,FLUID141单元,选择一个很大的矩形范围内填充空气,中间挖去一个矩形区域作为水平长条的截面。我的边界条件设定为:水平长条截面边界恒温(65度),x,y方向速度约束为0,空气左右下边界恒温(25度),不约束速度,上边界温度速度都不约束。请问这样设置边界条件正确吗?另外,在后处理中我发现,无论我把空气温度设定为多少度,程序中的对流换热系数都是用表面热流密度除以(长条表面温度-20度)来计算的,按说应该是表面热流密度除以(长条表面温度-空气温度)才对啊,这是怎么回事?
APDL命令如下:
!水平长条自然对流换热系数
FINISH
/FILNAME,file090612,0
/PREP7
W=100e-3
H=10e-3
XJ=300e-3
SJ=1000e-3
ZB=300e-3
YB=300e-3
Tair=273+25
Tsur=273+65
!*
ET,1,FLUID141
RECTNG,0,ZB,0,XJ,
RECTNG,0,ZB,XJ,XJ+H
RECTNG,0,ZB,XJ+H,SJ
RECTNG,ZB,ZB+W,0,XJ,
RECTNG,ZB,ZB+W,XJ,XJ+H
RECTNG,ZB,ZB+W,XJ+H,SJ
RECTNG,ZB+W,ZB+W+YB,0,XJ,
RECTNG,ZB+W,ZB+W+YB,XJ,XJ+H
RECTNG,ZB+W,ZB+W+YB,XJ+H,SJ
ADELE, 5
AGLUE,ALL
ESIZE,0.002,0,
AMESH,ALL
/UI,MESH,OFF
ALLSEL,ALL
NSEL,S,LOC,X,0
D,ALL, ,Tair, , , ,TEMP, , , , , !空气左边界恒温
NSEL,S,LOC,X,ZB+W+YB
D,ALL, ,Tair, , , ,TEMP, , , , , !空气右边界恒温
NSEL,S,LOC,Y,0
D,ALL, ,Tair, , , ,TEMP, , , , , !空气下边界恒温
NSEL,S,LOC,Y,XJ
NSEL,R,LOC,X,ZB,ZB+W
D,ALL, ,Tsur, , , ,TEMP, , , , ,
D,ALL,VX,0
D,ALL,VY,0 !长条下边界恒温、零速
NSEL,S,LOC,Y,XJ+H
NSEL,R,LOC,X,ZB,ZB+W
D,ALL, ,Tsur, , , ,TEMP, , , , ,
D,ALL,VX,0
D,ALL,VY,0 !长条上边界恒温、零速
NSEL,S,LOC,X,ZB
NSEL,R,LOC,Y,XJ,XJ+H
D,ALL, ,Tsur, , , ,TEMP, , , , ,
D,ALL,VX,0
D,ALL,VY,0 !长条左边界恒温、零速
NSEL,S,LOC,X,ZB+W
NSEL,R,LOC,Y,XJ,XJ+H
D,ALL, ,Tsur, , , ,TEMP, , , , ,
D,ALL,VX,0
D,ALL,VY,0 !长条右边界恒温、零速
ALLSEL,ALL
!!!!!!!!!!!!!!!!!!!!!!!!analysis define
nsel,all
esel,all
fldata1,solu,temp,1
fldata2,iter,exec,100
fldata2,iter,over,10
fldata5,outp,sumf,50
!!
fldata13,vary,dens,1
fldata7,prot,dens,air-si
fldata7,prot,visc,air-si
fldata7,prot,cond,air-si
fldata8,nomi,cond,-1
fldata7,prot,spht,air-si
!
acel,0,9.8,0
fldata18,meth,pres,1
fldata19,tdma,pres,100
fldata18,meth,temp,6
finish
/solu
allsel
solve
finish
/post1
set,last
plnsol,temp,,0, |