# uds flux - drift velocity - udf

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 August 11, 2011, 05:51 uds flux - drift velocity - udf #1 Member   john Join Date: Nov 2010 Posts: 50 Rep Power: 14 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 01:05.

 August 12, 2011, 06:29 #2 Member   john Join Date: Nov 2010 Posts: 50 Rep Power: 14 i need results badly. please somebody help!

 February 9, 2017, 11:26 #3 New Member   Join Date: Apr 2012 Posts: 17 Rep Power: 12 Hi, John, I'm facing exactly the same problem when using similar UDF. I was wondering if you had solved problem. If you had, could you share the solution? Thanks. Or if there is anyone knowing the soluation? Any suggestion would be highly appreciated.

 November 25, 2017, 05:07 SS..Any update on ion Density UDF #4 New Member   Tamil Nadu Join Date: Nov 2017 Posts: 2 Rep Power: 0 HI do you got any progress on above, kindly post your reply