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node values vs. no node values in fluent

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Old   August 26, 2011, 14:17
Default node values vs. no node values in fluent
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In fluent I am viewing filled velocity contours on my inlet.

When I check the box 'node values' and when I uncheck the box the results look dramatically different as shown in my two .png files attached.

If 'node value' means interpolation, how can it be that the two results have different orders of magnitude?

I have a 3D geometry spinning disk. The fluid is prescribed as a moving reference frame and the walls are prescribed at rotating at 0 rpm in the relative reference frame to the adjacent fluid. Does it have to do something with that?

Thanks.
Attached Images
File Type: jpg zvelocity_nodevalues.jpg (56.9 KB, 75 views)
File Type: jpg zvelocity_no_nodevalues.jpg (57.2 KB, 71 views)
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Old   August 28, 2014, 06:48
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Qureshi M Z I
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have you find the answer of this ? please share the answer

thanks
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Old   February 6, 2015, 06:03
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Quote:
Originally Posted by m zahid View Post
have you find the answer of this ? please share the answer

thanks
Hi
I have sampe problem, any answwer for this?
thanks
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Old   February 6, 2015, 06:32
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Cees Haringa
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Looking at the shown images, it looks like the left case is simply the velocity of the rotating frame plotted in the absolute frame, while the right case plots the z-velocity with respect to the reference frame. Because the actual velocities are an order of magnitude smaller than the frame velocity, the right one basically doesn't show anything. That's my idea on what we see here. Why we see it is a different question, and to that I have no answer currently.
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Old   June 30, 2019, 05:14
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If you are plotting contours to show the effect of a porous medium or fan, to depict a shock wave, or to show any other discontinuities or jumps in the plotted variable, you should use cell values; In other words for the fields with high gradiants the interpolation on the nods will result in false value.in such cases you have to choose either cell value or making mesh samaller. if you use node values in such cases, the discontinuity will be smeared by the node averaging for graphics and will not be shown clearly in the plot.
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