“…Furthermore, the system (1.4) is a natural example of a quasi-linear hyperbolic-elliptic mixed system of second order arising from the study of physical phenomena, therefore the main result obtained from this paper can provide a footstone in the study of a nonlinear hyperbolic-elliptic mixed type system of second order partial differential equations in a multidimensional domain. Moreover, we remove the extra compatibility conditions given in [1] in this paper. For a fixed constant L > 0, we define a nozzle Ω L of length L with a rectangular cross section D := (−1, 1) × (−1, 1) ⊂ R 2 by Ω L := (x 1 , x 2 , x 3 ) ∈ R 3 : 0 < x 1 < L, (x 2 , x 3 ) ∈ D .…”