December 10, 2019 at 7:44 pmDavidB7Subscriber
I am currently solving the case of forced convection across a heated horizontal cylinder (with constant surface temperature conditions). I know the equation to calculate the local Nu= - dT/dr (which is the temperature derivative along the normal vector to the cylinder surface).
I couldn't calculate the temperature derivative by using the expression tab in CFD-Post, i put the expression as follows: "Temperature.Gradient R @cylinder wall "
but it gives me the following error: "The following unrecognized name was referenced: Temperature.Gradient R"
P.S. i identified another variable "R" and its expression is sqrt(X^2 +Y^2) and i created a polyline at the cylinder surface and named it "cylinder wall"
December 11, 2019 at 10:56 amRobAnsys Employee
Try getting the output of Temperature.Gradient @cylinder wall and see what happens. As a more general comment, I mostly use _ and never a "space" when setting up models, expressions etc. Probably not needed any more, but was critical when I started using the software: it does mean I miss some issues!
December 11, 2019 at 3:17 pmDavidB7Subscriber
Thank you for replying!
Unfortunately, I tried this expression as well and got this error: "The following unrecognised name was referenced: Temperature.Gradient."
December 11, 2019 at 4:26 pmRobAnsys Employee
If you've come from Fluent have a look at Custom Field Functions and also the Thermal & Wall post-processing options. Check Temperature.Gradient exists too: it may not be defined in Post.
December 18, 2019 at 2:49 amDavidB7Subscriber
Hello Rwoolhou, i checked and i couldn't find it. However, i created an expression to calculate the local nusselt number and it worked fine for the steady state linear conditions.
I wanted to ask another question; can i ask here or should i make another post?
Thank you for your help!
December 18, 2019 at 11:58 amRobAnsys Employee
Another thread please: makes it easier to track.
December 24, 2020 at 1:02 pmMahmoudHISubscriberHello David,ni would like to ask you about the expression you used in finding the local Nusselt No. nyour clarification will be highly appreciated. Since I'm currently working on a similar problem where I have a fluid flowing into a horizontal tube with a uniform heat flux applied to the tube wall. n
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