scholarly journals Analisa Bentuk Foil pada Kapal Hydrofoil Supported-Catamaran (Hysucat)

2020 ◽  
Vol 4 (3) ◽  
pp. 145-156
Author(s):  
Yokhebert Natasya Siahaan ◽  
Samuel Samuel ◽  
Berlian Arswendo Adietya
Keyword(s):  
Fluid Flow ◽  
Numerical Method ◽  
High Speed ◽  
Lift Force ◽  
Water Phase ◽  
Navier Stokes ◽  
Hull Form ◽  
Reynolds Averaged Navier Stokes ◽  
Two Phases ◽  
Method Approach

ABSTRAKKapal katamaran yang terintegrasi dengan foil bertujuan untuk menghasilkan performance lebih baik. Hydrofoil Supported-Catamaran (Hysucat) merupakan kapal katamaran yang dirancang untuk kecepatan tinggi menggunakan foil. Penelitian ini dilakukan dengan pendekatan metode numerik untuk mempresentasikan aliran fluida menggunakan RANS (Reynolds-Averaged Navier-Stokes). Aliran fluida pada penelitian ini menggunakan dua fasa yaitu air dan udara untuk menganalisis hambatan dan gaya angkat kapal katamaran yang telah dimodifikasi menjadi hysucat. Hysucat pada penelitian ini dibedakan oleh tiga macam bentuk foil yaitu lurus, sweep belakang dan sweep depan dengan tambahan variasi pada chord line dan sudut serang foil. Penambahan foil pada penelitian ini memberikan informasi bahwa hysucat dengan bentuk foil sweep belakang chord line 1.2 dan AOA(sudut serang) 0º mengurangi hambatan kapal sebesar 21% dari hambatan kapal katamaran tanpa foil. Gaya angkat tertinggi dihasilkan hysucat dengan bentuk foil sweep belakang chord line 1 dan AOA (sudut serang) 0º sehingga bentuk foil yang direkomendasikan untuk digunakan adalah sweep belakang.Kata kunci: hysucat, hambatan, gaya angkat, foil, CFDABSTRACTCatamaran hull-form using foil aims to produce better performance. Hydrofoil Supported-Catamaran (Hysucat) is a catamaran which is designed for high-speed craft using foil. This research was conducted with a numerical method approach to present fluid flow using RANS (Reynolds-Averaged Navier-Stokes). The numerical method uses two phases, namely water phase, and air phase to analyze catamaran hull-form, which have been modified being hysucat. Hysucat is distinguished by three types of foil form namely straight foil, backward sweep foil, and forward sweep foil with additional variations in chord line and angle of attack (AOA). The addition of foil in this study provides information that hysucat with backward foil, chord line 1.2, and AOA 0º reduce ship resistance by 21% from catamaran resistance without foil. The highest lift force is produced by hysucat with backward foil, chord line 1 and AOA 0º so that foil form which is recommended to be used is backward sweep foil.Keywords: hysucat, resistance, lift force, foil, CFD

Reynolds-averaged Navier–Stokes simulation of hydrofoil effects on hydrodynamic coefficients of a catamaran in forced oscillation

2016 ◽  
Vol 231 (2) ◽  
pp. 364-383
Author(s):  
Amin Najafi ◽  
Mohammad Saeed Seif
Keyword(s):  
High Speed ◽  
Experimental Approach ◽  
Navier Stokes ◽  
Hydrodynamic Coefficients ◽  
Laboratory Equipment ◽  
Factors Affecting ◽  
High Frequencies ◽  
Frequency Independent ◽  
Reynolds Averaged Navier Stokes

Determination of high-speed crafts’ hydrodynamic coefficients will help to analyze the dynamics of these kinds of vessels and the factors affecting their dynamic stabilities. Also, it can be useful and effective in controlling the vessel instabilities. The main purpose of this study is to determine the coefficients of longitudinal motions of a planing catamaran with and without a hydrofoil using Reynolds-averaged Navier–Stokes method to evaluate the foil effects on them. Determination of hydrodynamic coefficients by experimental approach is costly and requires meticulous laboratory equipment; therefore, utilizing the numerical methods and developing a virtual laboratory seem highly efficient. In this study, the numerical results for hydrodynamic coefficients of a high-speed craft are verified against Troesch’s experimental results. In the following, after determination of hydrodynamic coefficients of a planing catamaran with and without foil, the foil effects on its hydrodynamic coefficients are evaluated. The results indicate that most of the coefficients are frequency-independent especially at high frequencies.

A Numerical Method for 3D Turbomachinery Aeroelasticity

2004 ◽  
Author(s):  
Paola Cinnella ◽  
Emanuele Cappiello ◽  
Pietro De Palma ◽  
Michele Napolitano ◽  
Giuseppe Pascazio
Keyword(s):  
Rigid Body ◽  
Numerical Method ◽  
Integral Form ◽  
Navier Stokes ◽  
Moving Grid ◽  
Time Step ◽  
Rans Equations ◽  
Standard Configuration ◽  
Reynolds Averaged Navier Stokes

This work provides an extension to 3D aeroelastic problems of a recently developed numerical method for turbomachinery aeroelasticity. The unsteady Euler or Reynolds-averaged Navier-Stokes (RANS) equations are solved in integral form, the blade passages being discretised using a deforming grid. The grid is regenerated at each time step using a novel methodology, that automatically avoids grid lines overlapping and guarantees the smoothness of the regenerated mesh. Firstly, the method has been validated versus the 2D 4th Aeroelastic Turbine Standard Configuration. Both inviscid and viscous turbulent computations have been performed, and the results previously obtained usind a different moving grid strategy have been recovered. In order to prove the robustness of the proposed deforming grid methodology, the same case has also been computed with the blade under-going large torsion displacements, the regenerated grid always preserving a good smoothness. Then, the methodology has been validated versus the 3D 4th Standard Aeroelastic Configuration, that involves a rigid body blade motion. Finally, a more severe 3D configuration, involving a clamped-beam-like blade deformation, has been considered.

Calculation of Debris Trajectories During High-Speed Snowplowing

2002 ◽  
Author(s):  
H. K. Nakhla ◽  
B. E. Thompson
Keyword(s):  
Particle Tracking ◽  
High Speed ◽  
Turbulence Modeling ◽  
Stokes Equations ◽  
Cutting Edge ◽  
Navier Stokes ◽  
Engineering Model ◽  
Navier Stokes Equations ◽  
Snow Plowing ◽  
Reynolds Averaged Navier Stokes

An engineering model is presented to calculate the trajectory of airborne debris that adversely affects visibility during high-speed snow plowing. Reynolds-averaged Navier-Stokes equations are solved numerically with turbulence-modeling, particle-tracking, and cutting-edge approximations. Results suggest snow can be divided into splash and snow-cloud when designing treatments to improve visibility for snowplow drivers and following traffic. Calculated results confirm the findings of windtunnel and road tests, specifically that the trap angle of overplow deflectors should be less than 50 degrees to eliminate snow debris blowing over top of the plow onto the windscreen.

A Pressure-Base One-Fluid Compressible Formulation for High Speed Two-Phase Flows With Heat and Mass Transfer

2018 ◽  
Vol 140 (8) ◽  
Author(s):  
Yan Luo ◽  
Jianqiu Zhou ◽  
Xia Yang ◽  
Zhanxiang Jiang
Keyword(s):  
Numerical Method ◽  
High Speed ◽  
Immiscible Fluids ◽  
Numerical Results ◽  
Cavitating Flows ◽  
Two Phase Flows ◽  
Two Phase ◽  
Two Phases ◽  
Locally Homogeneous ◽  
Homogeneous Media

This paper presents a numerical method for high-speed compressible cavitating flows. The method is derived from one-fluid formulation in a sense that the two phases are well mixed and the mixture is considered as a locally homogeneous media. Energy equation is solved to predict the temperature evolution which is then used together with pressure to update the density field. A volume of fluid (VOF) phase-fraction based interface capturing approach is used to capture the phase front between the two immiscible fluids. The derived formulations have been implemented into a pressure-based, segregated algebraic semi-implicit compressible solver in Openfoam, which can be used to solve for high-speed compressible two-phase flows involving phase changing. Numerical examples include the cavitating flows induced by an ultrasonic oscillating horn with and without a counter sample. The numerical results by the proposed method are validated against the published experimental data as well as numerical results and good agreements have been obtained. Our calculation demonstrates that the proposed numerical method is applicable to the study of high-speed two phase flows with phase transition and wave propagation, such as shock waves induced by the collapse of the cavitation bubbles.

The Effect of Flux Dysconnectivity Functions on Concentration Gradients Changes in a Multicomponent Model of Convectional Reaction-Diffusion by the Example of a Neurovascular Unit

2021 ◽  
Vol 413 ◽  
pp. 19-28
Author(s):  
Yaroslav R. Nartsissov
Keyword(s):  
Blood Flow ◽  
Fluid Flow ◽  
Blood Vessels ◽  
High Speed ◽  
Neurovascular Unit ◽  
Reaction Diffusion ◽  
Navier Stokes ◽  
Concentration Gradients ◽  
Navier Stokes Equation ◽  
Specific Trait

A convectional diffusion of nutrients around the blood vessels in brain occurs in well-structured neurovascular units (NVU) including neurons, glia and micro vessels. A common feature of the process is a combination of a relatively high-speed delivery solution stream inside the blood vessel and a low-speed convectional flow in parenchyma. The specific trait of NVU is the existence of a tight cover layer around the vessels which is formed by shoots (end-feet) of astrocytes. This layer forms so called blood-brain barrier (BBB). Under different pathological states the permeability of BBB is changed. The concentration gradient of a chemical compound in NVU has been modelled using a combination of mathematical description of a cerebral blood flow (CBF) and further 3D diffusion away from the blood vessels borders. The governing equation for the blood flow is the non-steady-state Navier–Stokes equation for an incompressible non-Newtonian fluid flow without buoyancy effects. BBB is modeled by the flux dysconnectivity functions. The velocity of fluid flow in the paravascular space was estimated using Darcy's law. Finally, the diffusion of the nutrient is considered as a convectional reaction-diffusion in a porous media. By the example of glucose, it was shown that increased permeability of BBB yields an increased level of the nutrient even under essential (on 70%) decrease of CBF. Contrarily, a low BBB permeability breeds a decreased concentration level under increased (on 50%) CBF. Such a phenomenon is explained by a smooth enlarge of the direct diffusion area for a blood-to-brain border glucose transport having three-level organization.

Reynolds-Averaged Navier-Stokes Simulations for High-Speed Wigley Hull in Deep and Shallow Water

2007 ◽  
Vol 51 (03) ◽  
pp. 187-203
Author(s):  
Nobuaki Sakamoto ◽  
Robert Vance Wilson ◽  
Frederick Stern
Keyword(s):  
Shallow Water ◽  
Message Passing ◽  
High Speed ◽  
High Performance ◽  
Message Passing Interface ◽  
Iterative Solvers ◽  
Verification And Validation ◽  
Navier Stokes ◽  
Wigley Hull ◽  
Reynolds Averaged Navier Stokes

Reynolds-averaged Navier-Stokes simulations and verification and validation studies for a high-speed Wigley hull in deep and shallow water are presented using CFD-SHIP-IOWA Version 4.00, which is a general-purpose ship hydrodynamics computational fluid dynamics code: single-phase level set free surface and k-w turbulence modeling; higher-order conservative discretization, embedded overset grids, advanced iterative solvers, and implicit coupling flow field and predicted motions numerical methods; and high-performance computing for message-passing interface (MPI)-based domain decomposition. The results are presented for low to high speed and deep to shallow water. The investigation is exploratory in nature using an idealized geometry and relatively coarse grids. Based on the verification and validation results, modifications for increased grid resolution at the bow for high speed and improved grid orthogonality for shallow water are made to obtain better solutions. The flow physics observations provide both integral and differential views of the highspeed and shallow-water flow fields, including resistance, pressure variation, wave pattern, boundary layer, and vortices.

Hydrodynamic Performance and Appendage Considerations of Wave-Piercing Planing Craft Overlapping Waves and Porpoising

2019 ◽  
Author(s):  
Sang-Won Kim ◽  
Sang-Eui Lee ◽  
Gyoung-Woo Lee ◽  
Kwang-Cheol Seo ◽  
Nobuyuki Oshima
Keyword(s):  
Numerical Simulation ◽  
Pressure Distribution ◽  
High Speed ◽  
Numerical Study ◽  
Hydrodynamic Performance ◽  
Moving Mesh ◽  
Navier Stokes ◽  
Hull Form ◽  
Wave Condition ◽  
Planing Craft

Abstract This work addresses the numerical study of wave-piercing planing hull and related hydrodynamic performance as the appendages. From the half century ago, the interest in high-speed planing crafts has been advanced toward maintaining performance stably. The main reasons to make it hard are instability motion occurring from porpoising and wave condition. Porpoising is mainly due to overlap the heaving and pitching motion with certain period, which is caused by instable pressure distribution and changing longitudinal location of center of gravity. In addition, in wave condition, encountering wave disturbs going into planing mode. This paper presents numerical results of wave-piercing planing hull in porpoising and wave condition. Numerical simulation is conducted via Reynolds Averaged Navier-stokes (RANS) with moving mesh techniques (overset grid), performed at different wave condition. The results for the behaviors of wave-piercing hull form are practically presented and investigated in this study. The understanding of these phenomena is important for design of appendages of wave-piercing hull-form.

scholarly journals Desenvolvimento de um modelo numérico para a predição de um escoamento em bocal do tipo H.O.M.E.R

2019 ◽  
Vol 5 (1) ◽  
pp. 129-137
Author(s):  
Elizaldo Domingues dos Santos
Keyword(s):  
High Speed ◽  
Navier Stokes ◽  
Reynolds Averaged Navier Stokes

No presente estudo é desenvolvido um modelo numérico para a abordagem de escoamentos turbulentos no regime permanente em bocais do tipo H.O.M.E.R (do inglês: High-speed Orienting Momentum with Enhanced Reversibility) que consiste na mistura de dois jatos incidentes sobre superfícies de Coanda. Essa superfície causa uma deflexão no escoamento permitindo que o bocal atue como um dispositivo de manobra em aplicações aeronáuticas. O principal objetivo é avaliar o modelo numérico desenvolvido comparando com resultados numéricos da literatura. As equações de conservação de massa e quantidade de movimento médias no tempo são resolvidas numericamente através do método de volumes finitos. Para resolver o problema do fechamento da turbulência foi empregada modelagem clássica (RANS – do inglês: Reynolds Averaged Navier Stokes) com modelo k – ε. Primeiramente, um teste de independência de malha será realizado, com o intuito de dispender menos recursos computacionais e obter resultados precisos. Em seguida, serão feitas as simulações em regime permanente, com o objetivo de obter os ângulos de deflexão (α) gerados com a diferença das vazões mássicas injetadas em cada um dos canais do bocal H.O.M.E.R (m*). Posteriormente, esses resultados são comparados com os obtidos numericamente na literatura. Os resultados obtidos tiveram o mesmo comportamento obtido na literatura, onde o aumento da diferença entre os jatos de entrada conduziu a um aumento no ângulo de deflexão do jato no bocal. Com exceção de um valor específico (m* = 0.2) os resultados obtidos no presente trabalho apresentaram uma boa concordância com os preditos numericamente na literatura.

The Evolution of Computational Methods in Aerodynamics

1983 ◽  
Vol 50 (4b) ◽  
pp. 1052-1070 ◽  
Author(s):  
A. Jameson
Keyword(s):  
Euler Equations ◽  
Computational Methods ◽  
High Speed ◽  
Stokes Equations ◽  
Inviscid Flow ◽  
Flow Equation ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Electronic Computers ◽  
Reynolds Averaged Navier Stokes

This paper surveys the evolution of computational methods in aerodynamics. Improvements in high-speed electronic computers have made it feasible to attempt numerical calculations of progressively more complex mathematical models of aerodynamic flows. Numerical approximation methods for a hierarchy of models are examined in ascending order of complexity, ranging from the linearized potential flow equation to the Reynolds averaged Navier Stokes equations, with the inclusion of some previously unpublished material on implicit and multigrid methods for the Euler equations. It is concluded that the solution to the Euler equations for inviscid flow past a complete aircraft is a presently attainable objective, while the solution to the Reynolds averaged Navier Stokes equations is a possibility clearly visible on the horizon.

Sign in / Sign up

Export Citation Format

Share Document