[mizan1605]

Sir,
I am new in ansys. I am doing a thesis for M.Sc purpose. I am working on Ansys 18.1 release with shell and tube heat exchanger. While I am going to iteration without baffles then everything is ok, but while I am going to iteration with baffles then two warning shows:
1. Reverse flow in pressure outlet
2. temperature limited to 1.000e+00001 in cells on zone 12 in domain 1

I fixed first error by changing inlet BC from mass flow inlet to velocity inlet. Is there any way to fix reverse flow in pressure outlet error without changing inlet BC? I have also tried with changing downstream, but no output.
And second one is "temperature limited to 1.000e+00001 in" this error is coming while using baffles. How can I fix it? Please help me with explanation as I am new in ansys. Please check the attached image

[ANTONY A R V]

Hi

There may be unrealestic thermal boundary conditions.

Pls check the temperature initial conditons also.

[mir9283]

I think it's a convergence problem.

You should display your temperature with contours to find the spots with 1 K and there you should refine your mesh.

Sometimes it's helpful to change your mesh to a polyhedral mesh. Therefor you have to use tetrahedral elements first by defining the mesh method as tetrahedral in the meshing tool. After that you change to Fluent and click on "make polyhedral". You find that button at "mesh" at the toolbar.

[mizan1605]

Originally Posted by mizan1605

Sir,
I am new in ansys. I am doing a thesis for M.Sc purpose. I am working on Ansys 18.1 release with shell and tube heat exchanger. While I am going to iteration without baffles then everything is ok, but while I am going to iteration with baffles then two warning shows:
1. Reverse flow in pressure outlet
2. temperature limited to 1.000e+00001 in cells on zone 12 in domain 1

I fixed first error by changing inlet BC from mass flow inlet to velocity inlet. Is there any way to fix reverse flow in pressure outlet error without changing inlet BC? I have also tried with changing downstream, but no output.
And second one is "temperature limited to 1.000e+00001 in" this error is coming while using baffles. How can I fix it? Please help me with explanation as I am new in ansys. Please check the attached image

Thanks for your valuable suggestions.
I have changed energy from udf section and the temperature limitations warning fixed. But now I am getting reverse flow warning. I have changed oultet be from pressure outlet to outflow. But warning is coming aster interation number 50

[ANTONY A R V]

Hi

Reverse flow may be because of the nature of the problem. there may positive pressure gradient or re-circulations. Need not change the BCs. Instead try to interpret the results.

Reverse flow will not lead to divergence.