Finite-element formulation for advection–reaction equations with change of variable and discontinuity capturing

We propose a change of variable approach and discontinuity capturing methods to ensure physical constraints for advection–reaction equations discretized by the finite element method. This change of variable confines the concentration below an upper bound in a very natural way. For the non-negativity constraint, we propose to use a discontinuity capturing method defined on the reference element that is combined with an anisotropic crosswind-dissipation operator. This discontinuity capturing cannot completely eliminate negative values but effectively minimizes their occurrence. The proposed methods are applied to different biophysical models and show a good agreement with experimental results for the FDA benchmark blood pump for a physiological red blood cell pore formation model. •Methods to enforce physical constraints on the concentration are discussed.•A change of variable is proposed to naturally impose a concentration upper bound.•Discontinuity capturing operators minimize unphysical negative values.•Hemolysis predictions for the FDA benchmark pump are compared with experiments.