[milkbag]

Dear all,

Here is my problem, I hope to realize the gas desorption by using UDF and code as follows:

DEFINE_SOURCE(CH4_mass_source, cell, thread, dS, eqn) /* defining the mass source ( the ch4 source)*/
{
cell_t c;
real source, p, p1;
real time_step=CURRENT_TIMESTEP;
int time_steps=RP_Get_Integer("time-step");
if(time_steps>1)
begin_c_loop(c,thread)
{
p=C_P(c,thread);
p1=C_P_M1(c,thread);
if (p>0 && p<p1)
{
source=(3.7*p1/(1570000+p1)-3.7*p/(1570000+p))/time_step; /* The Langmuir formula*/
}
else
{
source=0;
}
return source;
end_c_loop(c,thread);
}
}

However, this seems not work at all, or the program report errors.
I think the reason for this is that the C_P_M1 is not given memery. Who can help me to fix it? Thanks!