[FLASH-USERS] Diffuse_visc

[Dan D'Orazio]

I would like to know what exact scheme is being used in Diffuse_visc.F90
because,

In FLASH 3.2: I have altered the implementation of Diffuse_visc.F90 for
use in polar coordinates. Testing this against two analytic solutions, (an
alpha disk and the Greene's function solutions for a viscously spreading
ring of matter) I find a factor of 3 discrepancy. For example, If I set
the kinematic viscosity to 9, the simulation agrees with the analytic
result for kinematic viscosity=3. The changes I have introduced
(accommodating the angular coordinate) should not involve a factor of 3.

So, it would be helpful to know which exact scheme (something like
Crank-Nicolson?) is being used to compute the fluxes in Diffuse_visc.F90
in order to find possible erroneous numerical factors. Or if there is an
obvious reason why I should be obtaining the factor of 3 in polar
coordinates that would also be helpful.

Thanks for your help,

-Dan D'Orazio