This paper discusses the fluid turbulence structure and transport behavior of passive scalar (emitted from line sources aligned in the spanwise direction) in an open channel calculated by direct numerical simulation (DNS). The mathematical model consists of the unsteady Navier-Stokes, continuity and scalar transport equations. The implicit coupling between velocity and pressure is decoupled by the 2nd-order accurate fractional-step method. The spatial domain is discretized by the Galerkin finite element method with trilinear interpolating polynomials for velocity, pressure and scalar mixing ratio. The advection and diffusion terms are integrated in time by the 3rd-order accurate Runge-Kutta and the 2nd-order accurate Crank-Nicolson schemes, respectively. The Conjugate Gradient method is used to solve the linear equation systems. The detailed methodology of the calculation is discussed elsewhere.
展开▼
