# Changing Heat transfer coefficient

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 February 24, 2009, 06:05 Changing Heat transfer coefficient #1 Ashish Guest   Posts: n/a I want to solve a transient conduction problem in which one wall boundary condition is defined in terms of heat transfer coefficient. As time passes heat transfer coefficient will change with respect to avg temp of that wall.(so i want to correlate avg temp of wall at the end of each time step to the heat transfer bc) : > help Thanks in advance.

 February 24, 2009, 06:25 Re: Changing Heat transfer coefficient #2 Ralf Schmidt Guest   Posts: n/a go to solve->monitors->surface and set one surface monitor each time step for area weighted average Temperature at the wall and one surface monitor for area weighted average HTC. Best wishes Ralf

 February 24, 2009, 06:51 Re: Changing Heat transfer coefficient #3 Ashish Guest   Posts: n/a Thanks for help BUT I THINK I FAILED TO COMMUNICATE- one of the thermal bc for conduction is HT coefficient and T ambient which will remain constant (there is only constant option in drop down menu next to it). But HT coefficient itself is a function of avg wall temp. (which is changing as i am solving transient problem) So i want to teach code to take avg wall temp at the end of first time step put that into some formula and put the newly calculated HTC as bc for next time step and so on thanks

 February 24, 2009, 07:02 (PROBLEM IS UNSOLVED) *NM* #4 Ashish Guest   Posts: n/a

 February 24, 2009, 07:08 Re: (PROBLEM IS UNSOLVED) #5 mange Guest   Posts: n/a Hi, I think you have to code your function as a UDF. DEFINE_PROFILE i think should do the job. this way you can specify h as a function of whatever you want. /M