f i inviscid flux f vi viscous flux G Gradient for optimization I Cost function K ij Transformation functions between the physical domain the computational domain, K ij = ∂xi ∂ξj m f mass flow rate M Resultant cost function n i Unit normal vector in the ξ domain, pointing outward from the flow field N i Unit normal vector in the physical domain, pointing outward from the flow field R Gas constant s Entropy per unit mass S gen Entropy generation rate w Conservative flow variables, w = {ρ, ρu 1 , ρu 2 , ρu 3 , ρE} T x i Coordinates in the physical domaiñ β Mass-averaged exit flow angle Λ Weight of the penalty function ξ i Coordinates in the computational domain Ψ Co-state variables, Ψ = {ψ 1 , ψ 2 , ψ 3 , ψ 4 , ψ 5 } T