CFD mesh topology study of a truss geometry under forced oscillations

When it comes to numerical models based on the finite volume method, a technique used in many computational fluid dynamics (CFD) simulations, the numerical mesh adopted gains considerable importance for the result of the simulations. Refinements at certain points of the geometry, such as with the usage of prismatic layers to better capture the flow boundary layer, or in the numerical domain, such as with wake or jet regions, for example, can make the representation of the studied phenomenon more reliable. Using a more refined mesh has a significant relation with the final expected result, however, it also comes with the trade-off of a higher computational cost. This paper seeks to demonstrate and evaluate a method to improve mesh topology based on the quantity of elements, therefore related to its computational cost, and the final results of the simulation. For this, a truss geometry is evaluated under the condition of forced oscillation, and its hydrodynamic coefficients of added mass and drag are measured. For a specific oscillation condition, a study is made with three different mesh topologies in which the vortices formed from the movement are evaluated. In these cases, the mesh verification process is also presented in order to establish the numerical uncertainties associated with each of them. The forces acting on the simulated body are obtained numerically using a commercial CFD software, and the hydrodynamic coefficients are calculated using the Morison model with the least squares method.