Learning Forum

[scabo]

Hi

I am calculating the gradient of velocity, square of velocity, etc. in CFDPost from the data generated by Fluent. It is giving different values as compared to gradient calculated from Paraview from the same fluent data. Also when i calculate the gradient of square of velocity it gives 0 but in should not be zero. I am defining a new variable and using Gradient option to calculate the gradients in CFDPost. Any suggestions why this discrepancy is coming.

anny help?? thanks

[CFD_Friend]

Hi scabo,

Ansys Fluent calculates gradients internally during the simulation using specific numerical methods, such as Green-Gauss Cell Based, Green-Gauss Node Based, or Least Squares Cell Based. These are the "solver gradients". When you use a postprocessing tool like CFD-Post or Paraview, you are often calculating gradients after the simulation is complete, based on the discrete data available (which might be cell-centered or nodal values). The methods used by the postprocessing tools for these calculations are likely different from the methods used by the Fluent solver, and potentially different between CFD-Post and Paraview.

 

[scabo]

Hi, okay thanks. If i want to calculate the derivative of a user defined function like first/second derivative of Reynolds stress terms, then how can i do it in Fluent? Do i need to do after the simulation has ended using custom field funcs? I am currently struggling to do that in Fluent but i ahve done it in CFDPost and Paraview.