diff --git a/test/porenetwork/2p/main.cc b/test/porenetwork/2p/main.cc
index 4a017e43381ef293a04949aa0e70a2b7036a8969..db6a8d0e9e4c30e06227d1ba3c5cfe230ebbedd4 100644
--- a/test/porenetwork/2p/main.cc
+++ b/test/porenetwork/2p/main.cc
@@ -93,6 +93,7 @@ int main(int argc, char** argv)
     using SolutionVector = GetPropType<TypeTag, Properties::SolutionVector>;
     SolutionVector x(leafGridView.size(GridView::dimension));
     problem->applyInitialSolution(x);
+    problem->calculateSumInletVolume();
     auto xOld = x;
 
     // the grid variables
diff --git a/test/porenetwork/2p/params.input b/test/porenetwork/2p/params.input
index c406b2fac95e91c8fe030f64cc2daed2f3b03b49..4f994d96b7b64da4d597b9fc637e1b8a27d94987 100644
--- a/test/porenetwork/2p/params.input
+++ b/test/porenetwork/2p/params.input
@@ -13,6 +13,7 @@ VtpOutputFrequency = -1 # Write every n-th time step. 0 only writes a file if an
 EnableGravity = false
 CapillaryPressure = 5000
 UseFixedPressureAndSaturationBoundary = false
+DistributeByVolume = false
 
 [Vtk]
 AddVelocity = 1
diff --git a/test/porenetwork/2p/problem.hh b/test/porenetwork/2p/problem.hh
index f977e8df3d0f6e6d9701d25cfdb5129c1c821010..097121f9e0c7b8bb681e9b53a1fc17aa0801970c 100644
--- a/test/porenetwork/2p/problem.hh
+++ b/test/porenetwork/2p/problem.hh
@@ -73,7 +73,9 @@ public:
     {
         vtpOutputFrequency_ = getParam<int>("Problem.VtpOutputFrequency");
         useFixedPressureAndSaturationBoundary_ = getParam<bool>("Problem.UseFixedPressureAndSaturationBoundary", false);
+        distributeByVolume_ = getParam<bool>("Problem.DistributeByVolume", true);
         pc_ = getParam<Scalar>("Problem.CapillaryPressure");
+        nonWettingMassFlux_ = getParam<Scalar>("Problem.NonWettingMassFlux", 5e-8);
     }
 
     /*!
@@ -158,13 +160,17 @@ public:
     {
         PrimaryVariables values(0.0);
 
-        // If we do not want to use global phase pressure difference with fixed saturations and pressures,
-        // we can instead only fix the non-wetting phase pressure and allow the wetting phase saturation to changle freely
-        // by applying a Nitsche-type boundary condition which tries to minimize the difference between the present pn and the given value
+        // We fix the mass flux of non-wetting injection at inlet of pore-network
+        // The total inlet mass flux is distributed according to the ratio
+        // of pore volume at inlet to the total volumess
         if (!useFixedPressureAndSaturationBoundary_ && isInletPore_(scv))
-            values[snIdx] = (elemVolVars[scv].pressure(nPhaseIdx) - (1e5 + pc_)) * 1e8;
-
-        return values;
+        {
+            if (distributeByVolume_)
+                values[snIdx] = nonWettingMassFlux_ * ( scv.volume()/sumInletPoresVolume_ );
+            else
+                values[snIdx] = nonWettingMassFlux_ * std::pow((this->gridGeometry().poreInscribedRadius(scv.dofIndex())), 4.0)/sumInletPoresVolume_;
+        }
+        return values / scv.volume();
     }
     // \}
 
@@ -190,9 +196,29 @@ public:
     //!  Evaluate the initial invasion state of a pore throat
     bool initialInvasionState(const Element& element) const
     { return false; }
-
     // \}
 
+    //! Loop over the scv in the domain to calculate the sum volume of inner inlet pores
+    void calculateSumInletVolume()
+    {
+        sumInletPoresVolume_ = 0.0;
+        for (const auto& element : elements(this->gridGeometry().gridView()))
+        {
+            auto fvGeometry = localView(this->gridGeometry());
+            fvGeometry.bind(element);
+            for (const auto& scv : scvs(fvGeometry))
+            {
+                if (isInletPore_(scv))
+                {
+                    if (distributeByVolume_)
+                        sumInletPoresVolume_ += this->gridGeometry().poreVolume(scv.dofIndex())/this->gridGeometry().coordinationNumber(scv.dofIndex());
+                    else
+                        sumInletPoresVolume_ += std::pow(this->gridGeometry().poreInscribedRadius(scv.dofIndex()), 4.0);
+                }
+            }
+        }
+    }
+
 private:
 
     bool isInletPore_(const SubControlVolume& scv) const
@@ -212,7 +238,10 @@ private:
 
     int vtpOutputFrequency_;
     bool useFixedPressureAndSaturationBoundary_;
+    bool distributeByVolume_;
     Scalar pc_;
+    Scalar nonWettingMassFlux_;
+    Scalar sumInletPoresVolume_;
 };
 } //end namespace Dumux