NonlinearProblem nan tolerance

dolfinx
9

Little update:
I tried to implement a fix from this topic for phi1 in [0, 1]:

f = ufl.conditional(
    ufl.gt(phi1, 0), ufl.conditional(
        ufl.gt(phi1, 1), 0, phi1 / N1 * ufl.ln(phi1) + (1 - phi1) / N2 * ufl.ln(1 - phi1 ) + chi * phi1 * (1 - phi1)
        ), 
    0
    )

After this fix it stopped crushing, but now I have large negative values in phi1:

image
image665×561 55.2 KB

After that I tried to make a fix for phi:

phi1 = ufl.variable(
    ufl.conditional(ufl.gt(phi1, min_val), ufl.conditional(ufl.gt(phi1, 1), max_val, phi1), min_val)
    )

With conditional present at the same time for phi1 and f, the crashes came up again. So by now the only working solution is manually check values:

        for i in range(len(u.x.array[:])):
            if (u.x.array[:][i] + du.x.array[i]) <= EPS:
                du.x.array[i] = 0
                u.x.array[:][i] = EPS
            if (u.x.array[:][i] + du.x.array[i]) >= max_val:
                du.x.array[i] = 0
                u.x.array[:][i] = max_val

But in my opinion ignoring updates for finite elements looks like violations of the mass conservation law.