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October 7, 2009, 03:01 
a question about define heat flux

#1 
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patrick
Join Date: Apr 2009
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btw：the calculated h is listed belwo: AreaWeighted Average Surface Heat Transfer Coef. (w/m2k)   wall_coupled 743.67706 AreaWeighted Average Surface Heat Transfer Coef. (w/m2k)   wall_coupledshadow 738.45538 AreaWeighted Average Wall Func. Heat Tran. Coef. (w/m2k)   wall_coupled 6000.0054 #include "udf.h" DEFINE_HEAT_FLUX(heat_flux, f, t, c0, t0, cid, cir) { cid[0] = 0.; cid[1] = 3500; cid[2] = 3500; cid[3] = 0.; } 

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October 7, 2009, 03:44 

#2 
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patrick
Join Date: Apr 2009
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I modified the udf as below. and the results is listed below also. but the heat trasfer coef. is still not equal to h=3500, who know why? thank you very much
#include "udf.h" real h = 0.; /* heat transfer coefficient (W/m^2 C) */ DEFINE_ADJUST(htc_adjust, domain) { /* Define the heat transfer coefficient. */ h = 3500; } DEFINE_HEAT_FLUX(heat_flux, f, t, c0, t0, cid, cir) { cid[0] = 0.; cid[1] = h; cid[2] = h; cid[3] = 0.; } AreaWeighted Average Surface Heat Transfer Coef. (w/m2k)   wall_coupled 744.04559 AreaWeighted Average Wall Func. Heat Tran. Coef. (w/m2k)   wall_coupled 6000.0054 if i did not hooked it, then the results is as below: AreaWeighted Average Wall Func. Heat Tran. Coef. (w/m2k)   wall_coupled 6000.0054 AreaWeighted Average Surface Heat Transfer Coef. (w/m2k)   wall_coupled 902.71478 

October 7, 2009, 04:01 

#3 
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patrick
Join Date: Apr 2009
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I found that Surface Heat Transfer Coef. is defined by h=q/(T_wallT_ref), where q is the heat flux, T_wall is the wall temperature and T_ref is the reference temperature which means the average temperature of the fluid.
The default value of the T_ref is 288.16K. But I think maybe in different conditions the T_ref is different, so I would change it to the average temperature of the fluid. Actually I should set this T_ref to the fluid temperature close to the wall, where I want to know the htc. 

November 7, 2012, 23:36 
DEFINE_HEAT_FLUX usage

#4  
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Bruce
Join Date: Mar 2012
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hello,could please to introduce how to use the DEFINE_HEAT_FLUX Macro ?
ie. how to identify the special wall face ？ Quote:


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