Abstract:　A　CFD–DEM-based　two-phase　flow　model　and　a　test-based　erosion　model　are　used　to　obtain　the　specific　erosion　on　the　reducing　wall　of　sudden　contraction　section.　The　dimensionless　filtered　governing　equations　are　adopted　for　incompressible　power-law　fluid　flow,　and　the　Hertz–Mindlin　(no-slip)　model　for　particle–particle　and　particle–wall　contact.　The　annular　reducing　wall　is　divided　into　two　erosion　areas　in　radial　direction　based　on　erosion　form　and　divided　into　four　parts　in　the　circumferential　direction.　The　calculated　result　is　verified　with　a　full-scale　experiment,　and　it　shows　a　good　agreement.　The　calculated　results　show　that　the　erosion　rate　of　the　reducing　wall　is　mainly　determined　by　the　flow　velocity,　and　the　erosion　area　is　affected　by　liquid　viscosity.　The　serious　erosion　region　is　located　in　the　inner　edge　of　the　sample　lower　part,　and　this　region　expends　to　the　outer　circumference　with　the　increasing　flow　velocity　and　the　reducing　liquid　viscosity.　The　increase　in　flow　velocity　expands　the　flow　region　where　the　particle　can　impact　the　wall　and　thus　increases　the　particle　impact　numbers.　©　2017,　ASM　International.