Binary Mixed Type Partial Differential Equations Frankl Problems

In this paper, the unique existence of the Frankl problem and the relationship of the Frankl problem and Tricomi problem for a mixed equation of second order are studied.The coefficients of the equation are discontinuous on the connection line of the elliptic domain and the hyperbolic domain. The main results in the paper are the unique existence of the Frankl problem and that the solution of the Frankl problem converges to the solution of the Tricomi problem in H1 when the setting of the boundary conditions of the Frankl problem approaches that of the Tricomi problem.