Implementation of CLEARER algorithm on three-dimensional nonorthogonal curvilinear coordinates and its application

The newly proposed CLEARER algorithm is extended to three-dimensional nonorthogonal curvilinear coordinates. This algorithm can not only guarantee full coupling between the pressure and velocity terms, and solution independence of underrelaxation factors, it can also satisfy the physical and geometric conservation laws, hence it owns high efficiency and more robustness than its companion SIMPLE-like algorithms. To ease implementation of the CLEARER algorithm, the irregular physical domain is transformed to a regular computational domain, and correspondingly, the governing equations are also transformed. The mathematical formulations in both the predictor step and the corrector step are provided in detail, as well as the solution procedure. The CLEARER algorithm is adopted to simulate numerically the fluid flow and heat transfer in a triangular wavy fin-and-tube heat exchanger, and the influence of eccentricity and transverse tube pitch on the friction factor and Nusselt number is investigated in detail. It is found that the friction factor and Nusselt number increase with increasing eccentricity and decreasing transverse tube pitch.