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Hi all,
I want to simulate an forced oscillating cylinder immersed in a steady flow. 
The functions indicated in the MAPPING  section can be defined as:

1<FUNCTION NAME="Mapping">
2 <E VAR="x" VALUE="x" />
3 <E VAR="y" VALUE="y + cos(2*PI*t)" />
4 </FUNCTION>
5
6 <FUNCTION NAME="MappingVel">
7 <E VAR="vx" VALUE="0.0" />
8 <E VAR="vy" VALUE="-1.0*2*PI*sin(2*PI*t)" />
9 </FUNCTION>

I know that line 3 is the translational  displacement, Y = y + cos(2*PI*t);

line 8 is the corresponding velocity, which is the derivative of line 3. It may be written as  vY = vy -1.0*2*PI*sin(2*PI*t); but where is "Vy" in line 8? Does it omitted?

 If so, I would like to know how to set a case such as 
Y =   y*cos(2*PI*t)
Maybe, in line 3 it can be set as :  <E VAR="y" VALUE="y * cos(2*PI*t)" />
line 8 can be  <E VAR="vy" VALUE="-y*2*PI*sin(2*PI*t)+vy*cos(2*PI*t)" /> ?
but this setting seems dosen't work.

Could any one help me ?
Thank you!

Regards!

Howard