Verification and Validation of a Methodology to Numerically Generate Waves Using Transient Discrete Data as Prescribed Velocity Boundary Condition

Abstract

This work presents a two-dimensional numerical analysis of a wave channel and a oscillating water column (OWC) device. The main goal is to validate a methodology which uses transient velocity data as a means to impose velocity boundary condition for the generation of numerical waves. To achieve this, a numerical wave channel was simulated using regular waves with the same parameters as those used in a laboratory experiment. First, these waves were imposed as prescribed velocity boundary condition and compared with the analytical solution; then, the OWC device was inserted into the computational domain, aiming to validate this methodology. For the numerical analysis, computational fluid dynamics ANSYS Fluent software was employed, and to tackle with water–air interaction, the nonlinear multiphase model volume of fluid (VOF) was applied. Although the results obtained through the use of discrete data as velocity boundary condition presented a little disparity; in general, they showed a good agreement with laboratory experiment results. Since many studies use regular waves, there is a lack of analysis with ocean waves realistic data; thus, the proposed methodology stands out for its capacity of using realistic sea state data in numerical simulations regarding wave energy converters (WECs).

Numerical Analysis of an Overtopping Wave Energy Converter Subjected to the Incidence of Irregular and Regular Waves from Realistic Sea States

“…The verification and validation of the WaveMIMO methodology were carried out in Machado et al [18] and Maciel et al [38]. Therefore, for the sake of brevity, the verification of the numerical model used in the generation of waves will not be showed in the present paper.…”

“…These points are 2000 m away from the coas of the municipalities of Rio Grande (RG), Santa Vitória do Palmar (SVP), and Tavares (TV) Figure 1 represents the computational domain used for the simulation of the sea state of these points, through the TOMAWAC software. The generation of the realistic irregular waves in this study occurred through the WaveMIMO methodology [18], which was validated and verified in Maciel et al [38] Such methodology consists of imposing discretized orbital velocity profiles, horizonta and vertical, of the wave propagation as boundary conditions based on realistic sea state data.…”

“…where 𝜆 is the wavelength (m) and T is the wave period (s). Thus, by deriving the free-surface elevation equation for each coordinate axis, it is possible to obtain horizontal ( 𝑢 ) and vertical ( 𝑤 ) orbital velocity profiles of wave propagation given, respectively, by: The generation of the realistic irregular waves in this study occurred through the WaveMIMO methodology [18], which was validated and verified in Maciel et al [38]. Such methodology consists of imposing discretized orbital velocity profiles, horizontal and vertical, of the wave propagation as boundary conditions based on realistic sea state data.…”

“…Therefore, a twodimensional computational model was developed to simulate the operational principle of the device. It is worth mentioning that the 2-D numerical approach has been widely used for the investigation of WECs [18,21,22,38,43,44], including overtopping devices [6][7][8][9][10]13,15]. This simplification is reasonable especially for the overtopping WEC, since the physical phenomenon that occurred due to the incidence of waves can be adequately approximated as an in-plane problem.…”

Study of the Geometry of an Oscillating Water Column Device with Five Chambers Coupled under Regular Waves through the Constructal Design Method

“…For the execution of numerical works, it is necessary to validate and verify the numerical model to be used. Thus, the work of Maciel et al [10] presented a numerical investigation of an OWC device, during which they verified and validated a methodology for numerically generating waves using transient discrete data as a prescribed velocity boundary condition. Although there was a small discrepancy in the results obtained when using discrete data as a velocity boundary condition, they generally aligned with the results of laboratory experiments.…”