[soleimanian]

Hi
I want to simulate structure under wind flow in ANSYS Fluent.

for meshing, use of ICEM and hexahdral.

in set up my boundary were :
inlet=velocity
outlet=outflow
wall=wall (shear=0)
top=wall (shear=0)
building=wall (shear=0)
bottom=wall (shear=0)

K-epsilon model selected.

but when it run, see 3 things:
1. continuity show large number and didn't converged.
2. reversed flow from some faces in per iteration.
3. turbulent viscosity limited to viscosity ratio.

I don't know why appear their, and need to help for solve this error.
thanks for answering.

[divergence]

Check that your mass balance is correct. You could also check with pathlines starting from your inlet that the flow is more or less realistic. Check that there are no potential troublemakers in your mesh (bad quality cells, mysterious gaps or overlapping volumes). Check your URFs in case that they would be too high for your case.

[soleimanian]

may you explain more, because i know little about ANSYS fluent.
and please illustrate step by step check items you said?
or introduce reference for do them.

thanks a lot.

[soleimanian]

Originally Posted by divergence

Check that your mass balance is correct. You could also check with pathlines starting from your inlet that the flow is more or less realistic. Check that there are no potential troublemakers in your mesh (bad quality cells, mysterious gaps or overlapping volumes). Check your URFs in case that they would be too high for your case.

may you explain more, because i know little about ANSYS fluent.
and please illustrate step by step check items you said?
or introduce reference for do them.

thanks a lot.

[divergence]

I would recommend that you would refer for instance the ANSYS Fluent User Guide, which holds vast amount of important information. This document contains also tips on how to do many of the checks I mentioned. Mass balance is checked as the difference of inlet and outlet mass flows and URF is an acronym for under-relaxation factors. ANSYS probably offers many basic level tutorials, in which you can try out many of the said tools.

[soleimanian]

Originally Posted by divergence

I would recommend that you would refer for instance the ANSYS Fluent User Guide, which holds vast amount of important information. This document contains also tips on how to do many of the checks I mentioned. Mass balance is checked as the difference of inlet and outlet mass flows and URF is an acronym for under-relaxation factors. ANSYS probably offers many basic level tutorials, in which you can try out many of the said tools.

thank you

[Nourhan Bahgat]

Error when I run the calculation on FLUENT
Hi,
please anyone can help me what is the problem in this run so not convergence right low 1e-6

[vinerm]

What is the error? The attached image does not show any error. Furthermore, do not expect the residuals to drop to 1e-6. Even 1e-3 or 1e-4 might be good enough. It depends up on the values of the field variables. E.g., if velocity or pressure or temperature have very small value, such as, velocity being close to 0.1 m/s, then 1e-3 is not good enough and residuals should drop to at least 1e-4. But 1e-6 is not always required.