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Pressure/Density Gradient

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Old   October 6, 2013, 22:44
Default Pressure/Density Gradient
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Is there a way to plot either pressure or density gradients in Fluent (Fluid)? Or obtain values for for pressure and density derivatives in respect to x, y and z directions, such as dp-dx, dp-dy and dp-dz?
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Old   October 8, 2013, 11:36
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yes, go to Plots under Results, then under Y Axis Function choose derivatives and the tipe of Derivative you want. Also yo have to select the lines over wich you want to calculate the gradients. Hope this helps you. Regards. Gonzalo
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Old   October 9, 2013, 10:43
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Dear gfoam,

I do not see the "derivative" options under the "Y Axis Function." Do you think that I might be missing particular inputs?
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Old   October 9, 2013, 13:42
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I don't know why you can't see that, but here you can see an image of it:
derivatives.png
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Old   October 13, 2013, 20:13
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Dear gfoam,

Derivatives is still missing from that section. I do not see it as one of my options. Do you think that I might be missing something in the setup stage?

Since it is not working, is it valid to say that density in respect to the x direction is drho-dx since it is discretized?
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Old   October 15, 2013, 06:47
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Hi, I'm confused. If you solved your problem (I mean, if you press Calculate and let the software run) you must see the Results/Plots task page. There you can find the derivatives of velocity and pressure, but there isn't a derivative of density. To plot the derivatives of density you can use CFDPost, but I don't how you can do this in that software. Another option you can use is, export the density along the line you want to, and numerically find the derivatives in a spreadsheet. i hope this helps you. Regards. Gonzalo
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Old   December 5, 2013, 22:17
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Dear gfoam,

I went ahead and exported the pressure and density data to discretize them as dp/dx and drho/dx; however, I have no idea why derivatives do not show up (see figure). Do you happen to know why?
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