看看这两种做法为什么会有这样的结果差别？
这是消音器的那个例子，用两种方法求传递损失，第一种按照软件自带的步骤做的，得到的结果，第二种是按照网上有个兄弟的处理方法做的，两种方法结果不一样，为什么呢？
http://home.simwe.com/attachment/200905/18/389109_1242651201dd2e.gif
http://home.simwe.com/attachment/200905/18/389109_1242651201y143.gif
上面是按照消音器的例子 一步不差的做出来的结果。
具体步骤:
Environment Section SETUP BTNFILE 'muffler.BTN'
Return
Environment BTNFILE=mufflerNOFLOW.BTN Return
New Name 'noflow' Model 1 File noflow.sdb Return
OptionFEM Frequency Fluid Return
Import Mesh Format Free File muffler.fre Return
Material Fluid
Name 'air'
Sound 3.4000e+02Rho 1.2250e+00
Elements all
Return
Set 10 Name"inlet"
Faces Z=-.08
Return
Boundary VelocityReal -1 Imag 0
Faces Set 10
Return
Set 20 Name"outlet"
Faces Z=0.6
Return
Table 1 Name 'admittance' File admittance.tbl Return
Boundary Admittance Table 1
Faces Set 20
Return
SolveFrequency 20 To 300 LinStep 2 Return
Combine
Read Node 925 Pressure Return
Read Node 925 Pressure Return
Conjugate
Multiply
Root
Read Node 3244 Pressure Return
Read Node 3244 Pressure Return
Conjugate
Multiply
Root
Divide
Real
Log10
Constant Real 20 Imag 0
Multiply
Write Table 2 Name 'attenuation' Return
Return
下面的图是按照这个步骤做的。
OptionFEM Frequency Fluid Return
Import Mesh Format Free File muffler.fre Return
AxiSymmetry Return
Set 1 Name "inlet"
Face Z=-0.08
Return
Set 2 Name "outlet"
Face Z=0.6
Return
Material Fluid
Name 'air'
Sound 3.4000e+002Rho 1.2250e+000
Elements All
Return
Boundary VelocityReal -1 Imag 0
Faces Set 1
Return
Boundary AdmittanceReal 2.401e-3 Imag 0
Faces Set 2
Return
SolveFrequency 20 To 300 LinStep 2 Return
Combine
Read Node 925Pressure Return
Amplitude
Read Node 3244Pressure Return
Read Node 3244 VelocityVector 0 1 0 Return
Constant Real 416.5 Imag 0
Multiply
Add
Constant Real 2 Imag 0
Divide
Amplitude
Divide
Log10
Constant Real 20 Imag 0
Multiply
Write Table 1 name tl Return
Return
为什么结果不太一样呢？差在哪了呢？
另外在下面的步骤中设定导纳边界条件Boundary AdmittanceReal 2.401e-3 Imag 0
其中为什么在Real 中设置2.401e-3 ？怎么来的这个数据？
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