scholarly journals Experimental and Numerical Trimming Optimizations for a Mainsail in Upwind Conditions

2016 ◽  
Author(s):  
Matthieu Sacher ◽  
Frédéric Hauville ◽  
Régis Duvigneau ◽  
Olivier Le Maître ◽  
Nicolas Aubin ◽  
...  
Keyword(s):  
Numerical Model ◽  
Gaussian Process ◽  
Physical System ◽  
Numerical Models ◽  
Optimization Procedure ◽  
Performance Estimation ◽  
Direct Optimization ◽  
Structure Interaction ◽  
Two Parameters ◽  
Nonlinear Fluid

This paper investigates the use of meta-models for optimizing sails trimming. A Gaussian process is used to robustly approximate the dependence of the performance with the trimming parameters to be optimized. The Gaussian process construction uses a limited number of performance observations at carefully selected trimming points, potentially enabling the optimization of complex sail systems with multiple trimming parameters. We test the optimization procedure on the (two parameters) trimming of a scaled IMOCA mainsail in upwind conditions. To assess the robustness of the Gaussian process approach, in particular its sensitivity to error and noise in the performance estimation, we contrast the direct optimization of the physical system with the optimization of its numerical model. For the physical system, the optimization procedure was fed with wind tunnel measurements, while the numerical modeling relied on a fully nonlinear Fluid-Structure Interaction solver. The results show a correct agreement of the optimized trimming parameters for the physical and numerical models, despite the inherent errors in the numerical model and the measurement uncertainties. In addition, the number of performance estimations was found to be affordable and comparable in the two cases, demonstrating the effectiveness of the approach

scholarly journals A Novel Framework to Assess Soil Structure Interaction (SSI) Effects with Equivalent Fixed-Based Models

2021 ◽  
Vol 11 (21) ◽  
pp. 10472
Author(s):  
Davide Forcellini
Keyword(s):  
Numerical Simulations ◽  
Soil Structure ◽  
Numerical Models ◽  
Soil Structure Interaction ◽  
Structure Interaction ◽  
Non Linear ◽  
Period Elongation ◽  
Two Parameters ◽  
Main Effects ◽  
New Framework

Soil structure interaction (SSI) effects have been extensively studied with advanced numerical simulations even if these approaches are time consuming and require much effort to perform. In particular, when SSI models are compared with fixed based ones, two main effects need to be considered: period elongation and damping increase. The paper proposes numerical models to build fixed based models calibrated on these two parameters and perform complex SSI analyses. A new framework that may be used to assess SSI with equivalent fixed-based models is herein presented and validated with non-linear dynamic numerical simulations. Opensees was performed to reproduce non-linear numerical simulations by considering hysteretic materials and advanced soil models.

A Numerical Simulation of Nonlinear Fluid-Rigid Structure Interaction Problems

2002 ◽  
Author(s):  
J. T. Xing ◽  
W. G. Price ◽  
Y. G. Chen
Keyword(s):  
Numerical Model ◽  
Iteration Process ◽  
Nonlinear Boundary Conditions ◽  
Arbitrary Lagrangian Eulerian ◽  
Field Equations ◽  
Overset Grids ◽  
Structure Interaction ◽  
Rigid Structure ◽  
Nonlinear Fluid ◽  
Fluid Solid Interaction

A numerical method to simulate nonlinear fluid – rigid structure interaction problems is developed herein. The structure is assumed to undergo large rigid body motions and the fluid flow is governed by nonlinear, viscous or non-viscous, field equations with nonlinear boundary conditions applied to the free surface and fluid - solid interaction interfaces. An Arbitrary-Lagrangian-Eulerian (ALE) mesh system is used to construct the numerical model. A multi-block approach is adopted allowing relative motion between moving overset grids which are independent of one another. This provides a convenient method to overcome the difficulties of matching fluid meshes with large solid motions. Nonlinear numerical equations describing nonlinear fluid - solid interaction dynamics are derived through a numerical discretisation scheme of study. A coupling iteration process is used to solve these numerical equations. A numerical example is presented to demonstrate applications of the developed numerical model.

scholarly journals Preliminary Results on the Dynamics of a Pile-Moored Fish Cage with Elastic Net in Currents and Waves

2020 ◽  
Vol 9 (1) ◽  
pp. 14
Author(s):  
Gianluca Zitti ◽  
Nico Novelli ◽  
Maurizio Brocchini
Keyword(s):  
Numerical Model ◽  
Laboratory Experiments ◽  
Numerical Models ◽  
Offshore Structures ◽  
Fish Farm ◽  
Maximum Displacement ◽  
Drag Forces ◽  
Real Size ◽  
Lift And Drag ◽  
Mesh Grid

Over the last decades, the aquaculture sector increased significantly and constantly, moving fish-farm plants further from the coast, and exposing them to increasingly high forces due to currents and waves. The performances of cages in currents and waves have been widely studied in literature, by means of laboratory experiments and numerical models, but virtually all the research is focused on the global performances of the system, i.e., on the maximum displacement, the volume reduction or the mooring tension. In this work we propose a numerical model, derived from the net-truss model of Kristiansen and Faltinsen (2012), to study the dynamics of fish farm cages in current and waves. In this model the net is modeled with straight trusses connecting nodes, where the mass of the net is concentrated at the nodes. The deformation of the net is evaluated solving the equation of motion of the nodes, subjected to gravity, buoyancy, lift, and drag forces. With respect to the original model, the elasticity of the net is included. In this work the real size of the net is used for the computation mesh grid, this allowing the numerical model to reproduce the exact dynamics of the cage. The numerical model is used to simulate a cage with fixed rings, based on the concept of mooring the cage to the foundation of no longer functioning offshore structures. The deformations of the system subjected to currents and waves are studied.

scholarly journals CFD Investigation of Trout-Like Configuration Holding Station near an Obstruction

Fluids ◽  
2021 ◽  
Vol 6 (6) ◽  
pp. 204
Author(s):  
Kamran Fouladi ◽  
David J. Coughlin
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Laboratory Experiment ◽  
Numerical Models ◽  
Interaction Model ◽  
Underwater Vehicle ◽  
Water Stream ◽  
Hydrodynamic Analysis ◽  
Structure Interaction ◽  
Vehicle Systems

This report presents the development of a fluid-structure interaction model using commercial Computational fluid dynamics software and in-house developed User Defined Function to simulate the motion of a trout Department of Mechanical Engineering, Widener University holding station in a moving water stream. The oscillation model used in this study is based on the observations of trout swimming in a respirometry tank in a laboratory experiment. The numerical simulations showed results that are consistent with laboratory observations of a trout holding station in the tank without obstruction and trout entrained to the side of the cylindrical obstruction. This paper will be helpful in the development of numerical models for the hydrodynamic analysis of bioinspired unmanned underwater vehicle systems.

scholarly journals Development of Detailed FE Numerical Models for Assessing the Replacement of Metal with Composite Materials Applied to an Executive Aircraft Wing

Aerospace ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 178
Author(s):  
Valerio Acanfora ◽  
Roberto Petillo ◽  
Salvatore Incognito ◽  
Gerardo Mario Mirra ◽  
Aniello Riccio
Keyword(s):  
Composite Material ◽  
Composite Materials ◽  
Numerical Model ◽  
Numerical Models ◽  
Structural Performance ◽  
Aircraft Wing ◽  
Resin Infusion ◽  
Effectiveness Analysis ◽  
Liquid Resin Infusion ◽  
Process Constraints

This work provides a feasibility and effectiveness analysis, through numerical investigation, of metal replacement of primary components with composite material for an executive aircraft wing. In particular, benefits and disadvantages of replacing metal, usually adopted to manufacture this structural component, with composite material are explored. To accomplish this task, a detailed FEM numerical model of the composite aircraft wing was deployed by taking into account process constraints related to Liquid Resin Infusion, which was selected as the preferred manufacturing technique to fabricate the wing. We obtained a geometric and material layup definition for the CFRP components of the wing, which demonstrated that the replacement of the metal elements with composite materials did not affect the structural performance and can guarantee a substantial advantage for the structure in terms of weight reduction when compared to the equivalent metallic configuration, even for existing executive wing configurations.

A physically-based soil surface model and its combination with numerical models for predicting bare-soil evaporation rates

2021 ◽  
Author(s):  
Xiaocheng Liu ◽  
Chenming Zhang ◽  
Yue Liu ◽  
David Lockington ◽  
Ling Li
Keyword(s):  
Numerical Model ◽  
Surface Resistance ◽  
Numerical Models ◽  
Soil Column ◽  
Soil Surface ◽  
Bare Soil ◽  
Water Vapor Transport ◽  
Surface Model ◽  
Vapor Flow ◽  
Physically Based

<p>Estimation of evaporation rates from soils is significant for environmental, hydrological, and agricultural purposes. Modeling of the soil surface resistance is essential to estimate the evaporation rates from bare soil. Empirical surface resistance models may cause large deviations when applied to different soils. A physically-based soil surface model is developed to calculate the surface resistance, which can consider evaporation on the soil surface when soil is fully saturated and the vapor flow below the soil surface after dry layer forming on the top. Furthermore, this physically-based expression of the surface resistance is added into a numerical model that considers the liquid water transport, water vapor transport, and heat transport during evaporation. The simulation results are in good agreement with the results from six soil column drying experiments.  This numerical model can be applied to predict or estimate the evaporation rate of different soil and saturation at different depths during evaporation.</p>

Computational Modeling of Aortic Stenosis with a Reduced Degree-Of-Freedom Fluid-Structure Interaction Valve Model

2021 ◽  
Author(s):  
Chi Zhu ◽  
Jung-Hee Seo ◽  
Rajat Mittal
Keyword(s):  
Aortic Stenosis ◽  
Pressure Fluctuations ◽  
Fluid Structure Interaction ◽  
Degree Of Freedom ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Deceleration Phase ◽  
Wall Pressure Fluctuations ◽  
Two Parameters ◽  
Valve Model

Abstract In this study, a novel reduced degree-of-freedom (rDOF) aortic valve model is employed to investigate the fluid-structure interaction and hemodynamics associated with aortic stenosis. The dynamics of the valve leaflets are determined by an ordinary differential equation with two parameters and this rDOF model is shown to reproduce key features of more complex valve models. The hemodynamics associated with aortic stenosis is studied for three cases: a healthy case and two stenosed cases. The focus of the study is to correlate the hemodynamic features with the source generation mechanism of systolic murmurs associated with aortic stenosis. In the healthy case, extremely weak flow fluctuations are observed. However, in the stenosed cases, simulations show significant turbulent fluctuations in the asending aorta, which are responsible for the generation of strong wall pressure fluctuations after the aortic root mostly during the deceleration phase of the systole. The intensity of the murmur generation increases with the severity of the stenosis, and the source locations for the two diseased cases studied here lies around 1.0 inlet duct diameters ($D_o$) downstream of the ascending aorta.

scholarly journals Thermal-Structural Design of Actively-Cooled Panels Reinforced by Light-Weight Truss Cores

2013 ◽  
Author(s):  
Hongwei Song ◽  
Mingjun Li ◽  
Chenguang Huang ◽  
Xi Wang
Keyword(s):  
Heat Transfer ◽  
Structural Analysis ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Thermal Environment ◽  
Numerical Models ◽  
Lightweight Design ◽  
Optimization Procedure ◽  
Combustion Gas ◽  
Design Variables

This paper focuses on thermal-structural analysis and lightweight design of actively-cooled panels reinforced by low density lattice-framed material (LFM) truss cores. Numerical models for actively-cooled panels are built up with parametric codes to perform the coupled thermal-structural analysis, considering the internal thermal environment of convective heat transfer in the combustor and convective heat transfer in the cooling channel, and internal pressures from the combustion gas and the coolant. A preliminary comparison of the LFM truss reinforced actively-cooled panel and the non-reinforced panel demonstrates that the thermal-structural behavior is significantly improved. Then, an optimization procedure is carried out to find the lightest design while satisfying thermal deformation and plastic strain constraints, with thicknesses of face sheets and topology parameters of LFM truss as design variables. The optimization result demonstrates that, compared with the non-reinforced actively-cooled panels, weight reduction for the panel reinforced by LFM truss may reach 19.6%. We have also fabricated this type of actively-cooled panel in the laboratory level, and the specimen shows good mechanical behaviors.

The Research of Energy Conversion and Heat Transfer in the Ceramic Foams of Solar Energy Converter

2011 ◽  
Author(s):  
Yangbo Deng ◽  
Fengmin Su ◽  
Chunji Yan
Keyword(s):  
Heat Transfer ◽  
Numerical Model ◽  
Solar Radiation ◽  
Solar Energy ◽  
Numerical Models ◽  
Air Flow ◽  
Energy Converter ◽  
Ceramic Foams ◽  
Numerical Studies ◽  
Flow Through

The solar energy converter in Concentrated Solar Power (CSP) system, applies the solid frame structure of the ceramic foams to receive the concentrated solar radiation, convert it into thermal energy, and heat the air flow through the ceramic foams by convection heat transfer. In this paper, first, the pressure drops in the studied ceramic foams were measured under all kinds of flow condition. Based on the experimental results, an empirical numerical model was built for the air flow through ceramic foams. Second, a 3-D numerical model was built, for the receiving and conversion of the solar energy in the ceramic foams of the solar energy converter. Third, applying two aforementioned numerical models, the numerical studies of the thermal performance were carried out, for the solar energy converter filled with the ceramic foams, and results show that the structure parameters of the ceramic foams, the effective reflective area and the solar radiation intensity of the solar concentrator, have direct impacts on the absorptivity and conversion efficiency of the solar energy in the solar energy converter. And the results of the numerical studies are found to be in reasonable agreement with the experimental measurements. This paper will provide a reference for the design and manufacture of the solar energy converter with the ceramic foams.

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