[Nek5000-users] how to turn off conductivity/diffusion

[nek5000-users at lists.mcs.anl.gov]

I would like to model scalar transport without diffusion.
Now I model scalar transport with the help of temperature variable (as in examples.pdf).
If I just set parameter p0008 to zero or less than e-7 I got exception (background scalar gradient is about 100),
which is quite comprehensible because of the insulated boundary condition.
Even e-7 is quite a lot for my problem.
So is there a way to model scalar transport without diffusion, i.e. without RHS at all?
Or may be some trick with boundary conditions, which allows to set diffusion coefficient to zero?