SPLASH Nonlinear and Unsteady Free-Surface Analysis Code for Grand Prix Yacht Design

Rosen, Bruce S.; Laiosa, Joseph P.

doi:10.5957/csys-1997-014

Cited by 6 publications

(1 citation statement)

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“…Additionally, tools such as XFOIL [11] are popular for rapid evaluation of lift-drag polars and foil section design subject to a desired pressure distribution. Potential flow codes can be adapted to capture free surface effects and hence study the impacts of immersion and wave kinematics on appendage hydrodynamics [12]. On top of this, some of them can be run in real-time as part of a velocity prediction program (VPP) or dynamics simulator [3].…”

Section: Introductionmentioning

confidence: 99%

Developing methods of decomposing the physical resistance components acting on a hydrofoil

Chernyshev

Kabaliuk

Jermy

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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The America’s Cup is a sailing competition contested by teams fielding bespoke yachts designed and built to the AC75 class regulations. These yachts make use of hydrofoils, which permit them to lift their hulls above the water surface. When in this “foiling” regime, the drag forces on the hull are drastically lower, permitting greater sailing speed. Predicting hydrodynamic forces produced from hydrofoils on race yachts remains challenging, due to a wide operating regime and complex hydrodynamical phenomena. In this study, existing wake survey methods of decomposing the total drag force of a hydrofoil into physical subcomponents were developed through examining their sensitivities and accuracy. Computational fluid dynamics (CFD) simulations of a rectangular NACA4412 hydrofoil were performed to generate data for the wake surveys. The hydrofoil was simulated at a submergence depth of one chord. Viscous flow was simulated with the k–ω SST turbulence model in steady state; and the volume-of-fluid (VOF) model was used to capture free surface effects. Chord Froude numbers of 0.5, 1, 2 and 4 were investigated, corresponding to Reynolds numbers of 2.57 × 105, 5.15 × 105, 1.03 × 106 and 2.06 × 106. Force decomposition was performed using two different wake survey methods – one each for the wave and viscous drag – as well as Trefftz plane analysis for the induced drag. Wave drag forces could be reliably isolated at all tested Froude numbers, while reliable predictions of the viscous drag were dependent on the Froude number and method of isolating the hydrofoil’s viscous wake region. Accurately isolating the induced drag component proved challenging due to free surface interactions. Careful selection of the wake survey location was also necessary for accurate predictions of any of the drag components.

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Section: Introductionmentioning

confidence: 99%

Developing methods of decomposing the physical resistance components acting on a hydrofoil

Chernyshev

Kabaliuk

Jermy

et al. 2023

IOP Conf. Ser.: Mater. Sci. Eng.

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A combined pFFT‐multipole tree code, unsteady panel method with vortex particle wakes

Willis

Peraire

White

2006

Numerical Methods in Fluids

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SUMMARYPotential flow solvers for 3-D aerodynamic flows are commonly used in industrial applications. Two main difficulties preventing the even more widespread use of these codes are the limitations on the number of discretization elements and the user expertise and effort required to specify the wake location. In the paper we present an automatic wake generation strategy for a potential flow solver, and accelerate the method using a pFFT-Fast Multipole Tree algorithm. The combined method can be used to simulate both steady and unsteady flows. The steady state solution is achieved by running an unsteady flow simulation until it reaches a steady state. Computation results are given to demonstrate that the method is fast enough to automatically simulate entire heaving and flapping wing crafts in under and hour on a desktop computer.

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A hybrid scheme based on finite element/volume methods for two immiscible fluid flows

Wan

Aliabadi

Bigler

2009

Numerical Methods in Fluids

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SUMMARYWe have successfully extended our implicit hybrid finite element/volume (FE/FV) solver to flows involving two immiscible fluids. The solver is based on the segregated pressure correction or projection method on staggered unstructured hybrid meshes. An intermediate velocity field is first obtained by solving the momentum equations with the matrix-free implicit cell-centered FV method. The pressure Poisson equation is solved by the node-based Galerkin FE method for an auxiliary variable. The auxiliary variable is used to update the velocity field and the pressure field. The pressure field is carefully updated by taking into account the velocity divergence field. This updating strategy can be rigorously proven to be able to eliminate the unphysical pressure boundary layer and is crucial for the correct temporal convergence rate. Our current staggered-mesh scheme is distinct from other conventional ones in that we store the velocity components at cell centers and the auxiliary variable at vertices. The fluid interface is captured by solving an advection equation for the volume fraction of one of the fluids. The same matrix-free FV method, as the one used for momentum equations, is used to solve the advection equation. We will focus on the interface sharpening strategy to minimize the smearing of the interface over time. We have developed and implemented a global mass conservation algorithm that enforces the conservation of the mass for each fluid.

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SPLASH Nonlinear and Unsteady Free-Surface Analysis Code for Grand Prix Yacht Design

Cited by 6 publications

References 0 publications

Developing methods of decomposing the physical resistance components acting on a hydrofoil

Developing methods of decomposing the physical resistance components acting on a hydrofoil

A combined pFFT‐multipole tree code, unsteady panel method with vortex particle wakes

A hybrid scheme based on finite element/volume methods for two immiscible fluid flows

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