scholarly journals Hydrodynamic Analysis of Trimaran Vessels

2008 ◽  
Vol 15 (1) ◽  
pp. 11-18 ◽  
Author(s):  
M. Javanmardi ◽  
E. Jahanbakhsh ◽  
M. Seif ◽  
H. Sayyaadi
Keyword(s):  
Present Method ◽  
Three Dimensional ◽  
Solution Algorithm ◽  
Body Motion ◽  
Hydrodynamic Resistance ◽  
Hydrodynamic Behavior ◽  
Hydrodynamic Analysis ◽  
Hydrodynamic Simulations ◽  
Two Phases ◽  
Good Agreement

Hydrodynamic Analysis of Trimaran Vessels Trimaran vessels are developed for different applications and hydrodynamic behavior of such vessels is different than usual mono-hulls. In this paper hydrodynamic resistance and maneuvering of a trimaran with Wigley body form are investigated. The effects of outriggers position in four different longitudinal and two transverse locations are studied. For hydrodynamic simulations a CFD code has been developed and used. This code is capable for simulating three dimensional, time dependent, two phases, viscous flow coupled with rigid body motion. Formulation and solution algorithm are described in detail. Different case studies have been performance and numerical results have shown good agreement with experimental data. Based on resistance and maneuvering simulation of the trimaran vessels different conclusion are made. The results show that positions of outriggers have great effect on resistance and maneuverability of trimaran. The present method can be further employed to investigate other hydrodynamic qualities of trimaran vessels.

The Effect of the Steady Flow Potential on the Motions of a Moving Ship in Waves

2000 ◽  
Vol 44 (01) ◽  
pp. 14-32
Author(s):  
Ming-Chung Fang
Keyword(s):  
Steady Flow ◽  
Present Method ◽  
Three Dimensional ◽  
Source Distribution ◽  
Series Expansions ◽  
Ship Motions ◽  
Double Integral ◽  
Flow Potential ◽  
Principal Value ◽  
Good Agreement

A three-dimensional method to analyze the motions of a ship running in waves is presented, including the effects of the steady-flow potential. Basically, the general formulations are based on the source distribution technique by which the ship hull surface is regarded as the assembly of many panels. The present study includes three algorithms for treating the corresponding Green function:the Hess & Smith algorithm for the part of simple source I/r,the complex plane contour integral of the Shen & Farell algorithm for the double integral of steady flow, andthe series expansions of the Telste & Noblesse algorithm for the Cauchy principal value integral of unsteady flow. The study reveals that the effect of steady flow on ship motions is generally small, but it still cannot be neglected in some cases, especially for the ship running in oblique waves. The effect also depends on the fore-aft configuration of the ship. The results predicted by the present method are found to be in fairly good agreement with existing experiments and other theories.

scholarly journals Rotational Effects on Reynolds Stresses in the Solar Convection Zone

1991 ◽  
Vol 130 ◽  
pp. 98-100
Author(s):  
P. Pulkkinen ◽  
I. Tuominen ◽  
A. Brandenburg ◽  
Å. Nordlund ◽  
R.F. Stein
Keyword(s):  
Reynolds Stress ◽  
Convection Zone ◽  
Rotation Axis ◽  
Three Dimensional ◽  
External Parameter ◽  
Reynolds Stresses ◽  
Solar Convection Zone ◽  
Hydrodynamic Simulations ◽  
Solar Convection ◽  
Good Agreement

AbstractThree-dimensional hydrodynamic simulations are carried out in a rectangular box. The angle between gravity and rotation axis is kept as an external parameter in order to study the latitude-dependence of convection. Special attention is given to the horizontal Reynolds stress and the ∧-effect (Rüdiger, 1989). The results of the simulations are compared with observations and theory and a good agreement is found.

3D Vibration Analysis of Hermetic Capsules by Using Ritz Method

2017 ◽  
Vol 17 (03) ◽  
pp. 1750040
Author(s):  
Jae-Hoon Kang
Keyword(s):  
Eigenvalue Problem ◽  
Free Vibration ◽  
Vibration Analysis ◽  
Legendre Polynomials ◽  
Present Method ◽  
Ritz Method ◽  
Three Dimensional ◽  
Dynamic Equations ◽  
Vibration Frequencies ◽  
Good Agreement

A three-dimensional (3D) method of analysis is presented for determining the free vibration frequencies of a hermetic capsule comprising a cylinder closed with hemi-ellipsoidal caps at both ends. Unlike conventional shell theories, which are mathematically 2D, the present method is based upon the 3D dynamic equations of elasticity. Displacement components [Formula: see text], [Formula: see text], and [Formula: see text] in the radial, circumferential, and axial directions, respectively, are taken to be periodic in [Formula: see text] and in time, and the Legendre polynomials in the r and z directions instead of ordinary ones. Potential (strain) and kinetic energies of the hermetic capsule are formulated, and the Ritz method is used to solve the eigenvalue problem, thereby yielding upper bound values of the frequencies. As the degree of the Legendre polynomials is increased, frequencies converge to the exact values. Typical convergence studies are carried out for the first five frequencies. The frequencies from the present 3D method are in good agreement with those obtained from other 3D approach and 2D shell theories proposed by previous researchers.

Phase Field Simulation of Coarsening Kinetics in Al-Sc and Al-Sc-Zr Alloys

2008 ◽  
Vol 1128 ◽  
Author(s):  
H. Zapolsky ◽  
J. Boisse ◽  
R. Patte ◽  
N. Lecoq
Keyword(s):  
Phase Field ◽  
Diffusion Coefficients ◽  
Three Dimensional ◽  
Ternary Alloys ◽  
Simulation Results ◽  
Coarsening Kinetics ◽  
Two Phases ◽  
Kinetics Of ◽  
Good Agreement ◽  
Zr Alloys

AbstractThe coarsening kinetics of γ’ precipitates in binary and ternary Al3Sc1-xZrx alloys is studied by using the two- and three-dimensional phase-field simulations. Our focus is on the influence of diffusion coefficients of Sc and Zr atoms on the transformation path kinetics from disordered f.c.c. matrix to two phases equilibrium state with γ’ precipitates and f.c.c. disordered matrix. Our simulation results demonstrate that in the case of binary alloys taking into account the concentration dependence of the mobility of atoms decreases the coarsening rate. In the case of ternary alloys we show that the Al3Sc particles precipitate first following by appearance of a Zr-rich shell. Our simulations results are in good agreement with experimental observations.

Three-Dimensional Rotational Flow in Transonic Turbomachines: Part II—Full Three-Dimensional Flow in CAS Rotor Obtained by Using a Number of S1 and S2 Stream Filaments

1992 ◽  
Vol 114 (1) ◽  
pp. 50-60
Author(s):  
Wu Chung-Hua ◽  
Zhao Xiaolu ◽  
Qin Lisen
Keyword(s):  
Transonic Flow ◽  
Present Method ◽  
Three Dimensional ◽  
Flow Fields ◽  
Rotational Flow ◽  
Three Dimensional Flow ◽  
Measured Velocity ◽  
Dimensional Flow ◽  
Iterative Calculation ◽  
Good Agreement

The general theory for three-dimensional flow in subsonic and supersonic turbo-machines has recently been extended to transonic turbomachines. In this paper, which is Part II of the study, quasi- and full three-dimensional solutions of the transonic flow in the CAS rotor are presented. The solutions are obtained by iterative calculation between a number of S1 stream filaments and, respectively, a central S2m Stream filament and a number of S2 stream filaments. Relatively simple methods developed recently for solving the transonic flow along S1 and S2 stream filaments are used in the calculation. The three-dimensional flow fields in the CAS rotor obtained by the present method are presented in detail with special emphasis on the converging process for the configuration of the S1 and S2 stream filaments. The three-dimensional flow fields obtained in the quasi- and full three-dimensional solutions are quite similar, but the former gives a lower peak Mack number and a smaller circumferential variation in Mach number than the latter. A comparison between the theoretical solution and the Laser-2-Focus measurement shows that the character of the transonic flow including the three-dimensional shock structure is in good agreement, but the measured velocity is slightly higher than the calculated one over most of the flow field.

NUMERICAL SIMULATION ON TWO-PHASE BUBBLY FLOW SPLIT IN A BRANCHING T-JUNCTION

2011 ◽  
Vol 19 (04) ◽  
pp. 253-262 ◽  
Author(s):  
Y. LIU ◽  
W. Z. LI
Keyword(s):  
Model Simulation ◽  
Bubbly Flow ◽  
Bubble Diameter ◽  
Three Dimensional ◽  
Two Phase ◽  
Flow Parameters ◽  
Two Phases ◽  
Inertia Difference ◽  
Two Fluid ◽  
Good Agreement

In this paper, a steady three-dimensional two-fluid computational fluid dynamics predictive model is presented to simulate the dispersed bubbly flow split phenomenon in a T-junction with 50 mm diameter for all arms. The fluid is treated as a mixture and the fundamental mass, momentum and turbulent equations are solved to account for the flow parameters, where the turbulence is modeled by the standard k − ε model. Simulation results imply that the gas phase inclines to flow into the side arm even for small extraction rate conditions, because the pressure difference of the side arm to inlet is much larger than that of run arm to inlet. The analysis of velocity field reveals that it is the inertia difference between the two phases that leads to the phase split phenomenon. The effect of bubble diameter on flow split is also investigated and it is found that split efficiency is greatly influenced by it. The computed solutions are compared with experimental data and a good agreement is achieved.

scholarly journals Three-Dimensional Investigation of the Stokes Eigenmodes in Hollow Circular Cylinder

2013 ◽  
Vol 2013 ◽  
pp. 1-15
Author(s):  
Adil El Baroudi ◽  
Fulgence Razafimahery
Keyword(s):  
Present Method ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Finite Depth ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Element Analysis ◽  
Fluid Medium ◽  
Stokes Eigenmodes ◽  
Good Agreement

This paper studies the influence of boundary conditions on a fluid medium of finite depth. We determine the frequencies and the modal shapes of the fluid. The fluid is assumed to be incompressible and viscous. A potential technique is used to obtain in three-dimensional cylindrical coordinates a general solution for a problem. The method consists in solving analytically partial differential equations obtained from the linearized Navier-Stokes equation. A finite element analysis is also used to check the validity of the present method. The results from the proposed method are in good agreement with numerical solutions. The effect of the fluid thickness on the Stokes eigenmodes is also investigated. It is found that frequencies are strongly influenced.

scholarly journals Experimental and Numerical Investigation of Stepped Planing Hulls in Finding an Optimized Step Location and Analysis of Its Porpoising Phenomenon

2020 ◽  
Vol 2020 ◽  
pp. 1-18
Author(s):  
Sayyed Mahdi Sajedi ◽  
Parviz Ghadimi
Keyword(s):  
Experimental Data ◽  
High Speed ◽  
Three Dimensional ◽  
Single Step ◽  
Hydrodynamic Resistance ◽  
Resistance Reduction ◽  
Step Model ◽  
Volume Method ◽  
Mesh Technique ◽  
Good Agreement

Stability of a high-speed craft is an essential matter, and porpoising is one of the most critical instabilities that could occur in some planing hulls due to inappropriate design. In this paper, the porpoising phenomenon and variation of step location yielding resistance reduction are studied through experimental and numerical methods. The investigated models include a single-step model and a nonstep model with the same general shape, but with different step location. The nonstep model is previously tested, but the single-step model is examined in the present study. The nonstep model experiences porpoising at 8 m/s speed, but the single-step model remains stable at the same speed. A three-dimensional CFD analysis is conducted using the finite volume method (FVM). On the contrary, the volume of fluid (VOF) scheme is used for free surface modeling, and the overset mesh technique is implemented within StarCCM+ software. The CFD results of total hydrodynamic resistance and dynamic trim angle are compared against the experimental data. The numerical results are in good agreement with the experimental data. Subsequently, ten different stepped models are simulated to examine their effects. The longitudinal distance between steps and aft of these models are in the range of 19 to 50 percent of the length of models. The obtained results show that as steps are located farther than aft, the models become more stable, and resistance increases due to trim reduction. Finally, the optimum location of the step is extracted with the aim of minimizing the resistance through the design of experiment (DOE) method. Based on the DOE method, it is observed that the sensitivity of the drag value to the step location is higher than the speed.

Hydrodynamic Analysis and Motions of the Octoplus Platform

2004 ◽  
Author(s):  
R. Pascoal ◽  
C. Guedes Soares ◽  
G. Facon ◽  
F. Pe´trie´ ◽  
M. Vache´
Keyword(s):  
Experimental Program ◽  
Hydrodynamic Effect ◽  
Hydrodynamic Behavior ◽  
Local Pressure ◽  
Hydrodynamic Analysis ◽  
Code Comparison ◽  
Physical Testing ◽  
Construction Schedule ◽  
Wave Induced ◽  
Good Agreement

The hydrodynamic behavior of the OCTOPLUS, a new concept of FPSO is studied. The OCTOPLUS, stands for Optimum Concept TO Produce and Load with Underwater Storage and consists of surface piercing parallelepipedic columns and underwater storage caisson. It is designed for float over deck installation of its two main decks: production and utility deck. This enables fabrication of the decks to proceed in parallel with fabrication of the hull and therefore provides improvements in the construction schedule. The hydrodynamics are studied by physical testing and through numerical computations using a 3D radiation-diffraction code, comparison between both is provided. The experimental program encompasses 1, 10 and 100 year return period seas and the 6 DOF motions are measured. In addition to the comparison of motion transfer function modulus further calculations were performed in order to determine local pressure, having been found that there is a hydrodynamic effect peculiar to the interactions between waves scattered by the columns that is of some importance in design. The structure is shown to have exceptionally good hydrodynamic behavior in the sense that wave induced motions are small. Both the experimental and numerical results are in good agreement.

A Free Energy Perturbation Approach to Estimate the Intrinsic Solubilities of Drug-like Small Molecules

2019 ◽  
Author(s):  
Sayan Mondal ◽  
Gary Tresadern ◽  
Jeremy Greenwood ◽  
Byungchan Kim ◽  
Joe Kaus ◽  
...  
Keyword(s):  
Solid State ◽  
Small Molecules ◽  
Three Dimensional ◽  
Aqueous Solubility ◽  
Computational Approach ◽  
Free Energy Perturbation ◽  
Perturbation Approach ◽  
Energy Perturbation ◽  
State Form ◽  
Good Agreement

<p>Optimizing the solubility of small molecules is important in a wide variety of contexts, including in drug discovery where the optimization of aqueous solubility is often crucial to achieve oral bioavailability. In such a context, solubility optimization cannot be successfully pursued by indiscriminate increases in polarity, which would likely reduce permeability and potency. Moreover, increasing polarity may not even improve solubility itself in many cases, if it stabilizes the solid-state form. Here we present a novel physics-based approach to predict the solubility of small molecules, that takes into account three-dimensional solid-state characteristics in addition to polarity. The calculated solubilities are in good agreement with experimental solubilities taken both from the literature as well as from several active pharmaceutical discovery projects. This computational approach enables strategies to optimize solubility by disrupting the three-dimensional solid-state packing of novel chemical matter, illustrated here for an active medicinal chemistry campaign.</p>

Sign in / Sign up

Export Citation Format

Share Document