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-   -   Problems with HTC (http://www.cfd-online.com/Forums/cfx/73200-problems-htc.html)

NCMV March 2, 2010 02:44

Problems with HTC
 
Hi. Im doing my master thesis in heat transfer. Ive simulated a simple pipe, flowing liquid water both inside and outside. Flow is turbulent. In the post i see results trought a contour and variation of temperatures appear, but when i apply probe option the calculated values are differents in comparison to legend values. And the HTC values are higher. Im new in CFX, im very confuse.

Regards.

P.D.: excuse me for my English, im learning it.

ghorrocks March 2, 2010 17:57

What is your question? I think you are asking two questions:
1) Why are the probed temperatures different to the contours?
2) Why are the HTC values different between contours and probes?

Assuming these are your questions:
Be aware that the probe function in CFD-Post interpolates between adjacent nodes. This can lead to differences between the probed value and the contour value. Also the HTC only exists at the wall and is zero elsewhere. This means if your probe point is off the wall it will interpolate between the wall value and zero in the interior.

NCMV March 2, 2010 21:49

Hi Glenn. Thanks for your help. I didnt know about probe function interpolation. now i understand why the vaues are differents. I need to know about de HTC value at pipe anular area and somebody told me that i should use the function calculator and apply ave option but i dont be sure. Could you explain me better about tha HTC exists only at the wall?

Regards.

ghorrocks March 3, 2010 06:43

It is only meaningful to do area operations on HTC where the area is a wall. That is averaging, integration etc over a wall boundary. HTC only exists at the walls.

NCMV March 4, 2010 02:42

Hi Glenn. And if i want to know about a fluid HTC, how could i do? It should be a fluid on near wall?

Grettings.

ghorrocks March 4, 2010 06:47

I don't think you understand. Wall HTC only exists at the walls. It does not exist in the flow. You must be talking about some other HTC for the interior of the flow - maybe multiphase?


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