[Shawn_A]

Hi,

I'm getting different torque values depending on whether I use a surface that was defined in the solution or a user surface covering the same surface that was defined from a contour in Post.

First, I have my blade, blade1, which is a straight blade defined as a non-slip wall in CFX-Pre. There is a symmetry plane and condition at the middle of the blade, so it is really half of the blade. I defined a monitor point called TorqueZ_Blade1 with a definition of torque_z()@blade1. In the Table Viewer section of Post I put =torque_z()@blade1 and get the same value as the monitor point.

Since I would like to see the torque distribution along the blade, in Post I have defined a contour along this blade in the Z direction which essentially divides the blade into a number of slices. If I then create a User Surface based on the Z contour and attempt to sum torque_z()blade1contour1 through torque_z()@blade1contourN my sum is different from torque_z()@blade1.

After noticing the discrepancy between the two approaches, I tried to simplify problem by reducing the number of contours. The first contour has no area, so the simplest case is uses 2 contours, where contour 2 makes up the entire blade and therefore should be equivalent to the torque on the entire blade. Using this approach gave the same result as summing torques from the individual contours.

My next thought was perhaps that my Zmin and Zmax limits for the contour were inadvertently cutting of some area from the blade, so I redefined the limits to extend 1% beyond the blade on each side. Unfortunately this did not change the result.

I get a similar behaviour for forces as well.

So I am currently stuck with a discrepancy between the value of torque as calculated using the two methods described above. Has anyone encountered something like this or have any ideas why it is happening?

Thanks
Shawn