This　paper　presents　a　new　extension　of　the　realizable　K-epsilon　model　that　accounts　for　streamline　curvature,　system　rotation,　and　surface　roughness.　The　model　is　a　type　of　realizable　K-epsilon　model,　but　the　transport　equations　and　the　eddy-viscosity　damping　functions　are　modified,　based　on　the　Richardson　number　and　roughness　height;　the　roughness　correction　covers　both　the　transitional　and　fully　rough　regimes.　Flows　in　a　rotating　channel　and　a　U-bend　duct　are　used　to　validate　the　response　of　the　new　model　to　the　system　rotation　and　streamline　curvature.　The　flow　in　a　plane　channel　and　the　flow　over　a　dune　are　used　to　validate　the　roughness　extension.　Finally,　a　rotating　channel　with　rough　walls　is　studied,　to　test　the　new　model　when　both　rotation　and　roughness　are　present.