Learning Forum

[Prem1996]

How to calculate the strain rates using Fluent, specially when solving a Euler's equations? Solving Euler's equation means solving for Inviscid flow, where shear stresses are zero due to the zero viscosity ( the strain rates are not zero) However, Fluent is not allow me to calculate the strain rates (or maybe I am doing it wrong). Does any one know how to calculate the strain rates (such as del u / del y, del v/ del x) or the second derivative of the strain rates?? I tried using the custom field variable but since, I am solving for Euler's equation, fluent won't allow me to calculate the derivative functions using custom field functions nor I can calculate those using CFD-Post. Could someone help me with that please??

Thank You.

Regards,

Prem.

[Amine Ben Hadj Ali]

Under Derivatives.

[Prem1996]

Thank you for the response.
Could you please explain it little further. Like where can I find the option "Derivatives" ?

Thank You.

[aitor.amatriain]

Field Functions -> Custom -> Field Functions -> Derivatives

[Amine Ben Hadj Ali]

Derivatives is like Velocity is a category of Variables being available for post-processing.

[Prem1996]

Thank you for the response But I can't see "derivatives" options over there. The last option I can see is the "residual" one not the "derivative" one.
Are there any other option to Calculate those?
Thank You.
Regards,
Prem

[Prem1996]

Thank You for the response. But since I am solving for the Euler's equation (Inviscid Flow) this "Derivative" variable category seems to be vanished from the post- processing as well as from the fluent. I checked out all the variables and properties those variables have but din not able to locate the "Derivative" variable option. Instead of choosing inviscid model, if I choose the different physical model such as Laminar flow with very low viscosity then I can locate the "derivative" variable option over there. But not for the Inviscid physical model (Calculating for Euler's equations) I don't the reason behind that.
Anyways Thank You for your help. I appreciate that.
Thank You.
Regards Prem.

[Amine Ben Hadj Ali]

You can still access them in Fluent directly after telling Fluent to "Keep temporary solver memory from being freed?" /solve set expert (TUI). Reconstruction gradients are then accessible.

[Prem1996]

Thank You for giving me the solution. Could you please elaborate more like how I can do this??
Thank You.
Regards Prem

[aitor.amatriain]

In the Fluent Console, write solve/set/expert, and then answer Yes to the question "Keep temporary solver memory from being freed?"