# error while calculation

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June 26, 2018, 06:51
error while calculation
#1
New Member

Animesh Sahoo
Join Date: May 2018
Posts: 20
Rep Power: 4
Hi everyone,
Actually I am trying to solve the following equation(to calculate voltage from temperature difference) :-
∇V=-α(T)*∇T-ρ(T)*J , where α & ρ are known and for J(current density), first I have calculated I(current) from UDS1 and then then divided it by face area to calculate J.
And J is also implemented as boundary condition for UDS0.
∇UDS0=-ρ(T)*J
∇UDS1=-α(T)*∇T
And the code is in 2D.

Combined equation for UDS0, UDS1, J is as follows :-
Quote:
 #include "udf.h" #include "math.h" #define R 2.0 #define ID 5.0 real A[ND_ND],J; real At=0; enum { teg, teg1, N_REQUIRED_UDS }; real alpha_function(real T) { return 8.439e-4 - 3.81e-6*T + 6.736e-9*pow(T,-9.) - 3.934e-12*pow(T,-12.); } DEFINE_SOURCE(teg1_source, c, t, dS, eqn) { real T = C_T(c,t); C_UDSI(c,t,teg) = (-alpha_function(C_T(c,t)))*C_T_G(c,t)[0]; dS[eqn] = C_UDSI(c,t,teg1); return C_UDSI_G(c,t,teg1)[0]; } real rho_function(real T) { return -3.982e-5 + 2.98e-7*T - 4.685e-10*T*T + 2.51e-12*T*T*T; } DEFINE_ADJUST(teg_adjust, domain) { Thread *tf, *t; face_t f; cell_t c; tf = Lookup_Thread(domain, ID); t = THREAD_T0(tf); c=F_C0(f,tf); begin_f_loop (f,t) { F_AREA(A, f, t) ; At += NV_MAG(A); } end_f_loop (f,t) begin_f_loop (f,t) { J = F_UDSI(f,t,teg1)/R/At; } end_f_loop (f,t) } DEFINE_DIFFUSIVITY(teg_diffusivity, c, t, i) { C_UDSI(c,t,teg) = (-rho_function(C_T(c,t)))*(J); return 1./rho_function(C_T(c,t)); } DEFINE_PROFILE( J1, t, p) { face_t f ; begin_f_loop(f,t) { F_PROFILE(f, t, p) = J; } end_f_loop(f,t) }
But it gives 'fatal error' while calculation. I have also tried to eliminate some parts and run the code but it seems that diffusivity and rho function are looping with each other.
I hope someone will get it, whats wrong with the code.

 June 26, 2018, 21:34 #2 Senior Member   Alexander Join Date: Apr 2013 Posts: 1,638 Rep Power: 23 looks like you dont understand, how scalar works. look into this link. https://wenku.baidu.com/view/dd152b2...b.html?re=view there is a presentation which could be useful for you, however you should download it somehow. Unfortunately, I cant upload files. best regards