An Extended Verification and Validation Study of CFD Simulations for Planing Hulls

Abstract

In the context of marine application of computational fluid dynamic (CFD), it is well known that the numerical simulations of planing craft are significantly less reliable than that of displacement ships. For this reason, it is important to perform a comprehensive approach to the verification and validation (V&V) methodology and procedures for simulating CFD planing craft. In the first part of this paper, an assessment of the accuracy and effectiveness of different simulation setups and techniques for planing craft is performed. In the second part, the results of the V&V study are reported for three different hull models at four Froude numbers (Fr). The Unsteady Reynolds-Averaged Navier-Stokes code results were validated using benchmark experimental data obtained for three hull models characterized by systematic variation of the length to beam ratio. Grid independence, iteration, and time-step convergence analysis for response variables (resistance coefficients, wetted surfaces, and dynamic trim angles) were conducted using the main error and uncertainty estimation methods available in the literature. The same procedures were followed for the profiles of the wave patterns. The results showed that there was improved reliability of the numerical simulation of the planing craft in terms of the errors and uncertainties, related to the predictions of resistance, running attitude, and wave pattern. The results of the V&V study highlighted the fact that modeling of the planing

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

“…This procedure substitutes the estimated order of accuracy with 1 or 2 because the exponential power of error estimators to be selected (Equations ( 11) and ( 12)) is either 1 or 2. Slightly different from Eça and Hoekstra [31], De Luca et al [32] substitute p as the theoretical order of accuracy p th , i.e., p = p th = 2, when p * > 2. In fact, the method by De Luca et al [32] is more conservative, and it is applied in following calculations.…”

“…Considering that practical flow phenomenons are generally complex, and it is inevitable that p may be not in the range of [0.5, 2], Eça and Hoekstra [31] proposed another GCI method based on least-square roots (LSR-GCI). Such a method allows for error estimations even if the monotonic convergence is not achieved, and it is proven to be more reliable compared with GCI and CF based methods by De Luca et al [32]. Therefore, the LSR-GCI method [31] is applied for uncertainty estimations in this paper.…”

Performance Assessment of a Planing Hull Using the Smoothed Particle Hydrodynamics Method

“…It is noteworthy to observe that the high percentage error for the dynamic sinkage is strictly connected to the small values of this parameter. For a more comprehensive picture about the validity of the results here exposed, it is possible to refer to the results shown in De Luca et al, 2016 [18], where the URANS CD-Adapco Star-CCM+ is used. The general trend shown in this last work is almost in line with the results obtained through the presented SPH model for the higher resolution; it is possible to recognize the same inaccuracy when dynamic trim predictions are considered.…”

“…De Luca et al, (2016) [18] showed the results of a comprehensive V&V campaign of simulations of resistance test in still water condition using the hulls of the warped planing hulls of the Naples Systematic Series. The analysis depicts, for a wide range of speed and different hull shapes, the simulation uncertainty and the comparison errors.…”

Numerical Analysis of the Take-Off Performance of a Seaplane in Calm Water

“…The discretized governing equations are solved within active cells which update with the moving overset region. A linear interpolation scheme was used for linking the solution between the background region and the overset region for its efficiency and accuracy [17].…”