# uds flux - drift velocity - udf

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 August 11, 2011, 04:51 uds flux - drift velocity - udf #1 Member   john Join Date: Nov 2010 Posts: 50 Rep Power: 6 Hi All, I am calculation ion density using UDS udf, i have a flux term in transport equation as (u+mu.E). My udf is given below. I could see nothing wrong with my udf but ion density is rising gradually beyond input value with every iteration due to this term DEFINE_UDS_FLUX(ion_flux,f,t,i) { #if !RP_HOST double NV_VEC(A), NV_VEC(E_vec), F_Evec[ND_ND] = {0.}, E_flux = 0.; cell_t c0, c1 = -1; Thread *t0, *t1 = NULL; c0 = F_C0(f,t); t0 = F_C0_THREAD(f,t); F_AREA(A,f,t); if (BOUNDARY_FACE_THREAD_P(t)) { E_flux = 0.0; } else { c1 = F_C1(f,t); t1 = F_C1_THREAD(f,t); NV_DS(E_vec, =, E_X(c0,t0), E_Y(c0,t0), E_Z(c0,t0), *, ionmob); NV_DS(E_vec, +=, E_X(c1,t1), E_Y(c1,t1), E_Z(c1,t1), *, ionmob); E_flux = NV_DOT(E_vec,A)/2.0; } if (i==0) { return (F_FLUX(f,t)/rho+E_flux); } else return (0.); #endif #if RP_HOST return 0.0; #endif } After 3 iterations i could see that the iondensity value at the node near electorde is rising beyond my input value. Any suggestion are welcome. PS: I am stroing E_X, E_Y and E_Z values using memory option. Thanks John Last edited by johnwinter; August 12, 2011 at 00:05.

 August 12, 2011, 05:29 #2 Member   john Join Date: Nov 2010 Posts: 50 Rep Power: 6 i need results badly. please somebody help!

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