Enabling the Temperature Derivative in Ansys Fluent
In the post-processing step of numerical simulations, accurate quantitative results are often required more than just temperature and velocity contours. In some parameters, calculating the derivative of temperature is crucial. For instance, in the analysis of entropy generation, which is essential for optimizing thermal systems, calculating the exact quantitative value of temperature gradient plays a significant role. This necessity extends to various other parameters where precise results in each domain of the cell are needed.
Recognizing this, we understand the importance of enabling and utilizing the derivative of temperature within Ansys Fluent. This feature can be particularly beneficial when dealing with parameters that rely on temperature gradients at each cell in the simulation domain. Despite its importance, many users might not be aware of how to activate and apply this feature effectively.
In this tutorial, we will guide you through the process of enabling the temperature derivative in the custom field function calculator of Ansys Fluent. You will learn step-by-step how to access this feature and utilize it for your specific simulation needs, ensuring you can accurately compute parameters like entropy generation and beyond.
Watch the video below to learn how to enable and use the derivative of temperature in the custom field function calculator of the Ansys Fluent:
Dear [CFD Expert / Technical Support],
I am working on entropy generation analysis in an impinging jet configuration using ANSYS Fluent 19.1 for simulation and CFD-Post 19.1 for post-processing. I defined a custom entropy generation expression in CFD-Post (using “From Expression”), but encountered an issue when plotting the result on a wall surface. After defining a custom scalar field variable Sgentotal in CFD-Post (via Tools > Expressions and then “From Expression”), I attempt to plot it as a contour on the wall surface targetplate. However, I receive the following error:
‘Vertex’ values for Variable ‘Sgentotal’ do not exist on Geometry /DATA READER/CASE:Case FLU/BOUNDARY:targetplate.
Could you please advise on:
How to define an expression-based variable like Sgentotal such that it is evaluated at vertices (nodes) and is usable on surface boundaries (like targetplate) in CFD-Post 19.1?
Dear Sabah, Thank you for your comment. Your issue is not familiar to me. For calculating the entropy generation, we need to calculate the temperature gradient. Normally, when you save your case, and then you want to re-open it, before getting data in Ansys Fluent, I had to run the case for one iteration, and then I get the data. That’s how Ansys Fluent can calculate the temperature gradient. Maybe that data will not transfer to the CFD post on Vertex. In your case, you can get the contour from Ansys Fluent directly. But, if you want to get it in CFD-post, you can export the calculated entropy generation data for the CFD-post and then provide your figure as you wish. Hope this can help you.