Mesh Properties for RANS Simulations of Airfoil-Shaped Profiles: A Case Study of Rudder Hydrodynamics

Abstract

A good mesh is a prerequisite for achieving reliable results from Computational Fluid Dynamics (CFD) calculations. Mesh properties include mesh types, computational domain sizes, and node distributions. However, in literature, we found no clear consensus about what these properties should be. In this article, we performed a case study on ship rudders to determine what the suitable mesh properties are for airfoil-shaped profiles. A classic NACA 0012 profile is chosen as an example, and commercial packages ANSYS ICEM are applied for meshing with an ANSYS Fluent solver. With a strategy in consideration of relationships among different mesh properties, a comprehensive parametric investigation is conducted to study the impacts of these properties on the accuracy of rudder hydrodynamic coefficients obtained by CFD methods. The step-by-step study outputs recommended Reynolds numbers, domain sizes, and near- and far-field node distributions for mesh types with distinct topology structures, i.e., C-mesh, O-mesh, H-mesh, and Hybrid-mesh. Specifically, the study shows that a critical Reynolds number is needed for the perspective of efficiency, while a domain extending 60 times of the chord length enables the boundary effects to be negligible. As for node distributions, the near-field nodes should be treated carefully, compared with those in the far-field. After that, corresponding mesh properties for different calculation objectives are illustrated in detail based on the characteristics of mesh types mentioned above. With the proposed strategy for mesh refinements, impacts of different mesh properties on rudder hydrodynamics are clarified and recommended settings are applicable for other airfoil-shaped profiles such as wind turbines and marine propellers.

Implementation of a PAFV turbulence model for airfoil flow simulation on OpenFOAM

“…Figure 12 shows a comparison of the experimental values [24] with the lift coefficients (C L ) of the airfoils, which have been calculated using the three turbulence models at different angles of attack. The horizontal coordinate, α, indicates the incoming angle of attack of the airfoils.…”

“…They obtained some factors that affect the aerodynamic performance of the NACA0015 airfoil. In addition, other studies [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] have focused on the wing winding problem, and important conclusions were obtained.…”

Preliminary assessment of the NACA0021 trailing edge wedge for wind turbine application

“…Various mesh attributes enhance mesh quality, resulting in better accuracy of calculation outcomes by minimizing computing time wastage. The study by Lu et al [ 53 ] comprehensively examined various mesh parameters and their impact on the accuracy of solution predictions. The present investigation employed a structured C-type mesh.…”

Ship Dynamics and Hydrodynamics

“…The study performed by Lu et al [16] is indirectly associated with ship manoeuvrability as its results may turn out to be useful for a reliable prediction of the open-water hydrodynamic characteristics of rudders. The paper represents a significant contribution to the practice of the application of CFD codes and grid generators.…”