Learning Forum

[RozinaNalbandian]

Hello,

We are encountering an issue that is preventing our energy residual to converge in an energy-only simulation. When the simulation is run, messages saying "temperature limited to..." appear in the console and the energy residuals spike dramatically, preventing convergence.

For reference, this simulation is composed of two parts. First, a steady state simulation using flow and turbulence equations run in "Setup". Second, an energy simulation using the energy equation subsequently run in "Solution."

Our error occurs when we run a transient calculation with only the energy equation on in “Solution”. The file can be downloaded and viewed here: https://drive.google.com/drive/folders/1GOp_4uSrldzzxAGGEGpYAPDFeeZkabrR?usp=sharing

This file should be opened in the “Solution” tab which should already be setup to run a small time step size a couple of times. Our goal is to run about 1.5 hours of flow time with energy convergence with residuals at 1e-6.

Attached is a screenshot of the console and a screenshot of sample residuals are attached to this inquiry. Additionally, the ANSYS file and a diagram displaying the entire system is included with labels identifying the zones described in the console messages.

Any ideas on how to resolve it?

Sincerely,

Rozina Nalbandian

[Rob]

What is the max skew in the mesh? n

[RozinaNalbandian]

n

[RozinaNalbandian]

What is the max skew in the mesh?https://forum.ansys.com/discussion/comment/110404#Comment_110404

I performed a mesh quality check and mesh check:nIf this isn't what you were looking for can you instruct me on how to get the skewness?nn

[Rob]

That'll explain it. Check the mesh quality in the metal part of the pipe, an ortho quality below about 0.05 to 0.1 is likely to cause problems. n