# linear temperature profile + convection heat transfer

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 February 8, 2015, 07:29 linear temperature profile + convection heat transfer #1 Member   ad Join Date: Apr 2014 Posts: 75 Rep Power: 10 hello,I have a problem that I hope someone would help me,I'm simulating a 2D duct that has 15 parallel solid stacks in it,the horizontal walls in the stack section are given a constant temperature with a gradient from 700k down to 300k over a distance of 10 mm utilizing udf,the heat transfer coefficient between the stack walls and the fluid is 50 W/m^2.k, I have problem to model the convection heat transfer,I have written a udf for linear temperature profile but have difficulties to write a udf for convection heat transfer,my approach was to enter the convection heat transfer as a source term in energy equation but I'm not sure whether this is a right approach or not,this is my udf i hope that i can get some help,thanks ************************************************* DEFINE_PROFILE(linear_temp,thread,i) { real x[ND_ND]; real Th=700.0,Tc=300.0; real xh=30e-3,xc=40e-3; real dT=(Tc-Th)/(xc-xh); face_t f; begin_f_loop(f,thread) { F_CENTROID(x,f,thread); F_PROFILE(f,thread,i)=Th+(x[0]-xh)*dT; } end_f_loop(f,thread) } ************************************************** * DEFINE_SOURCE(SRCE_solid_heat,cell,thread,dS,eqn) { real h,Ts,Tf,source; h=50.0; Ts=????????????????????????(I dont know how to access the solid temperature); Tf=C_T(cell,thread); source=-h*(Ts-Tf); dS[eqn]=-h; return source; }

 February 9, 2015, 00:56 #2 Member   ad Join Date: Apr 2014 Posts: 75 Rep Power: 10 I'v managed a udf for fluid energy source term since i dont have any solid zone in my geometry,but i dont know whether this code is right or not,can anyone tell me????please, DEFINE_SOURCE(SRCE_fluid_heat,cell,t,dS,eqn) { real Tf,source; int ID=8 ; /* stack walls ID*/ face_t f; cell_t c; Domain*d; d=Get_Domain(1); t=Lookup_Thread(d,ID); Tf=C_T(cell,t); begin_f_loop(f,t) { source=50.0*(F_T(f,t)-Tf); } end_f_loop(f,t) dS[eqn]=-50.0; return source; }

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