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muneer Ismael (muneer)
Junior Member
Username: muneer

Post Number: 3
Registered: 12-2007
Posted on Tuesday, December 18, 2007 - 01:49 am:   

Dear Dr Nelson
Many thanks for your efforts. I have to make some calculations about certain variable say W in 3D cylindrical domain extruded along z-axis. I am inquiring about how I can calculate the average of (IW) over the circular cross-section, where IW is the distribution of the integration of W along z-axis i.e.
IW(r,theta)=integral[W(r,theta,z)dz].

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Robert G. Nelson (rgnelson)
Moderator
Username: rgnelson

Post Number: 1031
Registered: 06-2003
Posted on Tuesday, December 18, 2007 - 04:42 pm:   

It's not exactly clear what you want to do.

You can find IW by making it a variable with the equation dz(IW) = W. Impose a BC IW=0 at z=0. This does not just integrate W, but imposes a constraint that W=dz(IW), so define a reasonable initial value for IW. See the posts of "Integration in contour plot" of May 6, 2007.

You can integrate over a circular domain either by defining a circular region and using SURF_INTEGRAL, or by integrating over a larger surface and multiplying by a weight function that eliminates the part outside the circle.
The average is then SURF_INTEGRAL(IW)/SURF_INTEGRAL(1).
The denominator merely computes the surface area.

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