fix typo add &

dumux/flux/shallowwaterviscousflux.hh

@@ -211,13 +211,13 @@ public:
             }
         }();
 
-        // Compute the viscous momentum fluxes, take coneccting water depth at the interface
+        // Compute the viscous momentum fluxes with connecting water depth at the interface
         using std::min;
         using std::max;
         const auto freeSurfaceInside = insideVolVars.waterDepth() + insideVolVars.bedSurface();
         const auto freeSurfaceOutside = outsideVolVars.waterDepth() + outsideVolVars.bedSurface();
         const auto interfaceWaterDepth = max(min(freeSurfaceInside , freeSurfaceOutside) - max(insideVolVars.bedSurface(),outsideVolVars.bedSurface()),0.0);
-        const auto [gradU, gradV] = gradVelocity;
+        const auto& [gradU, gradV] = gradVelocity;
         const auto uViscousFlux = turbViscosity * interfaceWaterDepth * gradU;
         const auto vViscousFlux = turbViscosity * interfaceWaterDepth * gradV;