Merge branch 'fix/1pncForDifferentPhaseIdx' into 'master'

Fix/1pnc for different phase idx

See merge request !1102

dumux/porousmediumflow/1pnc/volumevariables.hh

@@ -117,7 +117,11 @@ public:
                                                                                compIIdx,
                                                                                compJIdx);
         }
-
+        // The diffusion coefficients are swapped, the general procedure for the flux
+        // calculation always goes form phaseIdx = 0 to numPhaseIdx.
+        // Swapping the coefficients ensures that the diffusion coefficient for compIdx == 0
+        // is always defined.
+        std::swap(diffCoeff_[0],diffCoeff_[mainCompMoleOrMassFracIdx]);
     }
 
     /*!
@@ -315,6 +319,9 @@ public:
 
     /*!
      * \brief Return the binary diffusion coefficient \f$\mathrm{[m^2/s]}\f$ in the fluid.
+     *
+     * \note For fluidSystemPhaseIdx > 0, the diffusion coefficients
+     *        diffCoeff_[0] and  diffCoeff_[mainCompMoleOrMassFracIdx] are swapped
      */
     Scalar diffusionCoefficient(int phaseIdx, int compIdx) const
     {

[Timo Koch]

i don't understand this. it also doesn't become clear from the comment why we swap the diffusion coefficients?

[Timo Koch]

it also says the calculation of fluxes goes from 0 to numPhases but the phaseIdx is ignored when evaluating or storing the diffusion coefficient

[Timo Koch]

it also says the swap is done so that diffCoeff_[0] is defined. It was also defined before. And after the swap it will be always zero, since diffCoeff_[mainCompMoleOrMassFracIdx] is zero. It's unclear to me why diffCoeff_[0] should be always zero?