In flow field, the pressure, which usually drives the fluid to flow, is one of the most important variables. However, in the conventional computational method, density, velocity, and temperature or stagnation internal energy are usually used as basic unknown variables, as well as the pressure, a key factor for fluid dynamics, is usually solved indirectly by pressure correction or applying the equation of state. By rational mathematical deduction, a set of new general unified equations for fluid dynamics are deduced in this paper. In these equations, the static pressure and static enthalpy are adopted as basic unknown variables.

We will combine linear successive overrelaxation method with nonlinear monotone iterative scheme to obtain a new iterative method for solving nonlinear equations. The basic idea of this method joining traditional monotone iterative method (known as the method of lower and upper solutions) which depends essentially on the monotone parameter is that by introducing an acceleration parameter one can construct a sequence to accelerate the convergence. The resulting increase in the speed of convergence is very dramatic. Moreover, the sequence can accomplish monotonic convergence behavior in the iterative process when some suitable acceleration parameters are chosen. Under some suitable assumptions in aspect of the nonlinear function and the matrix norm generated from this method, we can prove the boundedness and convergence of the resulting sequences. Application of the iterative scheme is given to a logistic model problem in ecology, and numerical results for a test problem with known analytical solution are given to demonstrate the accuracy and efficiency of the present method.