Fix: r Default in AddPlasmaFlux

[ax3l]

It appears to me that in the case of EBs with inject_from_eb the variable r.y is used as undefined in case that we do not randomize the theta.

See: line 1666ff. below the line I changed for the use of r.y in the case of multiple modes and/or non-random theta:

                const Real theta = (nmodes == 1 && rz_random_theta)?
                    (2._prt*MathConst::pi*amrex::Random(engine)):
                    (2._prt*MathConst::pi*r.y);

What would be a good default value? I think zero might actually not what we want here... but maybe something depending on pos in that case.

[dpgrote]

Good catch. I think in this case, it might be better to set r.y = amrex::Random(engine) with EB and inject_from_eb. The r.y is setting the theta and it would be good to have this uniformly distributed. Another option would be to take the setting of r outside of the else block and always call getPositionUnitBox. This would allow the user to select between uniformly spaced theta and random theta.

[ax3l]

Not the solution. I think we need to set r to pos inside if (inject_from_eb) or so