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stanstanne银虫 (正式写手)
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[求助]
【已完结】FLUENT 换热系数UDF的编写求助
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希望学习FLUENT UDF的虫友帮帮忙，关于施加换热系数边界条件的UDF。 问题描述：一根有厚度圆管，内部有导热油流过，外部有带速度的空气流过，如下图。  但是不知道定义换热系数边界条件用什么宏。 看help文件，发现DEFINE_PROFILE和DEFINE_HEAT_FLUX好像都可以，但是没有例子 自己不会编，希望虫友们给点建议 [ Last edited by 1592203609 on 2017-3-6 at 16:04 ] |
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/**************declaration of the functions***************************/ real dry_air_density(real temp); real dry_air_specific_heat(real temp); real dry_air_thermal_conductivity(real temp); real dry_air_dynamic_viscosity(real temp); ………………………… ………………………… mu_outer=dry_air_dynamic_viscosity(temp_outer); mu_air=dry_air_dynamic_viscosity(temp_air); lambda_outer=dry_air_thermal_conductivity(temp_outer); 这些声明的函数可以直接用来取值吗，udf内部有这些函数吗，udf是怎么识别这些函数的？？？？？求问 |
9楼2017-10-27 09:09:05
stanstanne
银虫 (正式写手)
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没人回吗，好吧，自己顶，希望会UDF的大神可以给点建议 昨天找到一个相关话题，感兴趣的虫友可以看一下。 链接：http://muchong.com/html/201304/5739908.html |
2楼2017-03-06 14:58:02
stanstanne
银虫 (正式写手)
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刚才成功编译换热系数的UDF，感谢http://muchong.com/html/201304/5739908.html上附的代码。 现在把自己写的代码放在下面，很长，希望对感兴趣的虫友有所帮助 /* UDF used to calculate the forced convection between the bare absorber tube and the air around it.*/ #include "udf.h" #define D_outer 0.07 #define temp_air 293.15 #define speed_air 3 /**************declaration of the functions***************************/ real dry_air_density(real temp); real dry_air_specific_heat(real temp); real dry_air_thermal_conductivity(real temp); real dry_air_dynamic_viscosity(real temp); /*thread is a pointer to the face's thread, and position is a numerical lbael for the variable being set within each loop*/ DEFINE_PROFILE(forced_convection_air_abs, thread, position) { real mu_outer, lambda_outer, Cp_outer, rho_outer, mu_air, lambda_air, Cp_air, rho_air, v_air; /*transitional parameters*/ real nu_outer, nu_air, alpha_outer, alpha_air, Re_outer, Pr_outer, Pr_air; /*coefficients of Zhukausas's correlation*/ real m, n, C; real temp_outer;/*temperature of the outerer absorber tube*/ real Nu_outer_air, h_outer_air; /*Nusselt number to calculate forced heat transfer coefficient*/ face_t f; begin_f_loop(f,thread) { temp_outer=F_T(f,thread); /*the process to obtain the property value of the air*/ /*Via the linear fitting method, we can obtain the expression of the properties of the air varying with the temperature, temperature ranges from 20 Celsius to 400 Celsius*/ mu_outer=dry_air_dynamic_viscosity(temp_outer); mu_air=dry_air_dynamic_viscosity(temp_air); lambda_outer=dry_air_thermal_conductivity(temp_outer); lambda_air=dry_air_thermal_conductivity(temp_air); Cp_outer=dry_air_specific_heat(temp_outer); Cp_air=dry_air_specific_heat(temp_air); rho_outer=dry_air_density(temp_outer); rho_air=dry_air_density(temp_air); nu_air=mu_air/rho_air; nu_outer=mu_outer/rho_outer; alpha_air=lambda_air/(Cp_air*rho_air);/* make sure that the unit of the parameters is international*/ alpha_outer=lambda_outer/(Cp_outer*rho_outer); Re_outer=speed_air*D_outer/alpha_air; /*the Reynold number of flowing air*/ Pr_outer=nu_outer/alpha_outer; Pr_air=nu_air/alpha_air; /*if Re_outer is used outer of range, print warning information on the screen*/ /**********waiting to complete********************/ /*if Pr_air is used outer of range, print warning information on the screen*/ /**********waiting to complete********************/ /*coefficients for external forced convection Nusselt Number correlation(Zhukausas's correlation)*/ if(Pr_air<=10) n=0.37; else n=0.36; if(Re_outer<40) { C=0.75; m=0.4; } else if(Re_outer>=40 && Re_outer<1000) { C=0.51; m=0.5; } else if(Re_outer>=1000 && Re_outer<2e5) { C=0.26; m=0.6; } else if(Re_outer>=2e5 && Re_outer<1e6) { C=0.076; m=0.7; } else printf("the Reynold number is out of the suitable range, the result may not be accurate!!\n"  ;/*Zhukauskas's correlation for external forced convection flow normal to an isothermal cylinder */ Nu_outer_air=C*pow(Re_outer,m)*pow(Pr_air,n)*pow(Pr_air/Pr_outer,1/4); F_PROFILE(f,thread,position)=Nu_outer_air*lambda_air/D_outer; } end_f_loop(f,thread) } /*declaration of the function calculating the dry air density*/ real dry_air_density(real temp) { real rho; if(temp>=273.15 && temp<=673.15) rho=3.60759e-6*temp*temp-0.00532*temp+2.44735; else printf("the temperature is out of range, the result may not be accurate!!\n" ;return rho; } /*declaration of the function calculating the dry air specific heat*/ real dry_air_specific_heat(real temp) { real Cp; if(temp>=273.15 && temp<=673.15) Cp=-8.23356e-10*pow(temp,3)+1.51078e-6*temp*temp-6.80959e-4*temp+1.09594; else printf("the temperature is out of range, the result may not be accurate!!\n" ;return Cp; } /*declaration of the function calculating the dry air thermal conductivity*/ real dry_air_thermal_conductivity(real temp) { real lambda; if(temp>=273.15 && temp<=673.15) lambda=-2.74554e-6*temp*temp-0.00952*temp+0.03672; else printf("the temperature is out of range, the result may not be accurate!!\n" ;return lambda; } /*declaration of the function calculating the dry air dynamic viscosity*/ real dry_air_dynamic_viscosity(real temp) { real mu; if(temp>=273.15 && temp<=673.15) mu=-2.0294e-5*temp*temp+0.05877*temp+2.72007; else printf("the temperature is out of range, the result may not be accurate!!\n" ;return mu; } |
3楼2017-03-06 15:56:38
4楼2017-03-09 11:11:53
