I'm writing a udf source file that adds up density gradient (x-component) along cell faces. It either takes cell gradent itself (along a boundary face) or average two neiboring cells (along a non-boundary face). There is no problem with the first case but something is wrong with C_R_G(c0,t0) and C_R_G(c1,t1) for the second case. It gives me a segmentation fault. It looks like C_R_G(c0,t0) and/or C_R_G(c1,t1) do not exist or references incorrectly.

Can somebody help?

Thanks. Sergei

DEFINE_SOURCE(FSD_source, c, t, dS, eqn) { int j; real value; Thread *t0, *t1 = NULL; Thread *tf; cell_t c0, c1 = -1; value=0;

c_face_loop(c, t, j) {

f=C_FACE(c,t,j);

tf=C_FACE_THREAD(c,t,j);

t0 = THREAD_T0(tf);

c0 = F_C0(f,tf);

if (BOUNDARY_FACE_THREAD_P(tf))

value+=C_R_G(c,t)[0]; else

{

t1 = THREAD_T1(tf);

c1 = F_C1(f,tf);

value+=(C_R_G(c0,t0)[0]+C_R_G(c1,t1)[0])/2;

} } return value; }

Try the text command solve/set/expert and answer "yes" to the question "Keep temporary solver memory from being freed?". This should preserve all gradients and not remove them continually from memory.

RoM

Hi,

you also might encounter problems in the first step: since you have no values no gradients can be built. So you can try adding a big loop around your UDF, e.g. "if (N_ITER>1) {...}"

Hope that helps ...