Learning Forum

[sjyang]

In ANSYS Fluent, scalar quantities such as temperature or enthalpy can be represented as vectors in the results section.

When a scalar quantity is represented as a vector, what does the direction of the vector arrow indicate? Does the direction of the arrow indicate the direction in which the scalar quantity is increasing?

Using the Custom Vector feature, I set the x, y, and z components all to temperature, and also set 'Color by' to static temperature.

[Rob]

Assuming you're plotting from Velocity Vectors the arrow is associated with the velocity vector and the colour is (in the above) temperature.  The Scene and Object overlays are relatively new (well 5-ish years) so before that if we wanted to overlay flow field and a scalar value we'd do what you're showing in the image. Now I'd tend to overlay a contour of temperature with vectors of velocity and alter the colourmap to avoid confusion. 

[sjyang]

 

In the attached image, "vectors of" is set to velocity by default, but by using the custom vector setting, the x, y, and z components can be set to scalar quantities like temperature. If the "vectors of" setting is set to temperature, what does the direction of the displayed vector indicate?

[Rob]

https://ansyshelp.ansys.com/account/Secured?returnurl=/Views/Secured/corp/v242/en/flu_ug/flu_ug_sec_graphics_basic.html%23flu_ug_sec_vectors_custom   What the vectors mean is a little more complicated.... 

[Rob]

And some more information. The vector (arrow) is likely based on the three components, so if you have a vector of x=angular-velocity=5; y=mass balance=1 and z=static pressure = 1500000 you'll have a vector arrow of size (5, 1, 1500000); we think. It's not a feature I've ever used. 

[sjyang]

I followed the link and read the explanation, but I couldn't find any details on what the direction of the vectors represents when setting the x, y, and z components to scalar quantities using the custom vector option. Could you let me know where I can find this explanation?

[Rob]

We don't think it's in the documentation, but my comment is likely correct. I'll log a DOC enhancement but that will take some time to action.