[heng94]

Hi all,

I had this problem upon calculation,

May I know how to solve this problem?
My simulation is about a double pipe cylindrical heat exchanger with constant heat on the surface of the outerpipe. The heat exchanger is only modelled 1/4 to take advantage of the cylindrical symmetry. The water is pumped through the "water-inlet" and allowed to flow to the bottom of heat exchanger and flow back up and exits via "water-outlet". The outer pipe is surrounded with earth rock where its temperature is 383 K. The flow is turbulent. Can anyone help? Thank you.



water inlet v = 0.5m/s
t = 283 K

surface of outer pipe = 383 K

the outer pipe is surrounded with earth rock where its temperature is 383 K. the flow is turbulent

[Kushal Puri]

Originally Posted by heng94

Hi all,

I had this problem upon calculation,

May I know how to solve this problem?
My simulation is about a double pipe cylindrical heat exchanger with constant heat on the surface of the outerpipe. The heat exchanger is only modelled 1/4 to take advantage of the cylindrical symmetry. The water is pumped through the "water-inlet" and allowed to flow to the bottom of heat exchanger and flow back up and exits via "water-outlet". The outer pipe is surrounded with earth rock where its temperature is 383 K. The flow is turbulent. Can anyone help? Thank you.



water inlet v = 0.5m/s
t = 283 K

surface of outer pipe = 383 K

the outer pipe is surrounded with earth rock where its temperature is 383 K. the flow is turbulent

This type of warnings are due to highly skewed elements (bad mesh). One way is just check the location where this warning is coming and remesh that region with good quality mesh.

If you want to proceed with the same mesh, just turn off the secondary gradient of the temperature by typint the following command in TUI

(rpsetvar 'temperature/shell-secondary-gradient? #f)

typpe the above command along with brackets and continue your run.

All the warnings will go after some iterations.

[LuckyTran]

Try a better initial guess.

[heng94]

Hi. Thanks for your reply. I had check my skewness quality with a maximum of 0.75. I'm using multizone method with hexa/prism mesh. I had already typed (rpsetvar 'temperature/shell-secondary-gradient? #f) in TUI command but the same problem with temperature being limited still exist. Please help. thank you.

[heng94]

A better initial guess? Do you mind to explain further? Thank you very much

[m.uzair]

Originally Posted by heng94

Hi all,

I had this problem upon calculation,

May I know how to solve this problem?
My simulation is about a double pipe cylindrical heat exchanger with constant heat on the surface of the outerpipe. The heat exchanger is only modelled 1/4 to take advantage of the cylindrical symmetry. The water is pumped through the "water-inlet" and allowed to flow to the bottom of heat exchanger and flow back up and exits via "water-outlet". The outer pipe is surrounded with earth rock where its temperature is 383 K. The flow is turbulent. Can anyone help? Thank you.



water inlet v = 0.5m/s
t = 283 K

surface of outer pipe = 383 K

the outer pipe is surrounded with earth rock where its temperature is 383 K. the flow is turbulent

Hi Heng94, did you manage to solve the problem?
If yes, please tell how did you do it

Best

[Far]

Originally Posted by m.uzair

Hi Heng94, did you manage to solve the problem?
If yes, please tell how did you do it

Best

I dont know what is causing problem in your case. But I managed to solve this problem by making proper mesh. By proper I mean I reduced the sudden change in mesh size in solid zone and made it almost uniform.