Simulation on the Process of Cavity Wall Expansion of Cone at Constant Speed Water-Entry

2013 ◽  
Vol 419 ◽  
pp. 97-102
Author(s):  
Wei Cao ◽  
Chun Tao He ◽  
Cong Wang
Keyword(s):  
Computational Simulation ◽  
Water Entry ◽  
Constant Speed ◽  
Cavity Wall ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Half Angle ◽  
Expansion Dynamic ◽  
Different Depths ◽  
Volume Method

Computational simulation investigation which is based on the Navier-Stokes equation, finite-volume method, dynamic mesh method, and volume of fluid method, was carried out principally on the constant speed vertical water entry of the cone with 75 degree and a half angle. Based on this, the cavity generation and the process of cavity wall expansion of the cone with 75 degree and a half angle were analyzed. Through analyzing the expansion dynamic for the cavity wall in different depths, the velocity and acceleration with time in the process of cavity wall expansion were obtained, and the disturbances and splash feature laws of the free surface near the entrance of the cavity after cones water-entry were analyzed too.

scholarly journals Simulation of free-surface flow in a tank using the Navier-Stokes model and unstructured finite volume method

2005 ◽  
Vol 219 (3) ◽  
pp. 251-266 ◽  
Author(s):  
X Zhang ◽  
N M Sudharsan ◽  
R Ajaykumar ◽  
K Kumar
Keyword(s):  
Free Surface ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Free Surface Flow ◽  
Offshore Structures ◽  
Surface Flow ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Volume Method ◽  
Unstructured Finite Volume Method

Modelling free-surface flow has very important applications in many engineering areas such as oil transportation and offshore structures. Current research focuses on the modelling of free surface flow in a tank by solving the Navier-Stokes equation. An unstructured finite volume method is used to discretize the governing equations. The free surface is tracked by dynamically adapting the mesh and making it always surface conforming. A mesh-smoothing scheme based on the spring analogy is also implemented to ensure mesh quality throughout the computaiton. Studies are performed on the sloshing response of a liquid in an elastic container subjected to various excitation frequencies. Further investigations are also carried out on the critical frequency that leads to large deformation of the tank walls. Another numerical simulation involves the free-surface flow past as submerged obstacle placed in the tank to show the flow separation and vortices. All these cases demonstrate the capability of this numerical method in modelling complicated practical problems.

scholarly journals SIMULASI NUMERIK FENOMENA SINGLE DROPLET MENGGUNAKAN METODE VOLUME HINGGA DAN FRONT-TRACKING

POROS ◽  
2018 ◽  
Vol 15 (2) ◽  
pp. 84
Author(s):  
Dondi Kurniawan ◽  
Eko Budiana ◽  
Deendarlianto Deendarlianto ◽  
Indarto Indarto
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Stokes Equations ◽  
Initial Step ◽  
Front Tracking ◽  
Navier Stokes ◽  
Single Droplet ◽  
Navier Stokes Equation ◽  
Front Tracking Method ◽  
Volume Method

Abstract: A numerical simulation of single droplet phenomena is conducted using a finite volume method. Interface between different phases is tracked by using a front-tracking method. Governing equations used in present paper consist of the continuity equation, the Navier-Stokes equation and the front-tracking equation. The unsteady Navier-Stokes equations are solved implicitly using the finite volume method on staggered mesh. The interfacial term such as surface tension is negligible and the viscosity of the fluid is considered equal. The completion of pressure term is solved by Successive Over-Relaxation (SOR) method. The validation of present paper result is conducted by comparing to Tryggvasson (2012) result using explicit scheme. The advantage of this research is using implicit scheme that is unconditional stable. This research is the initial step to model a single droplet impact on solid surface. In this research will be discussed representation of interface and dynamics of interface reconstruction. Finite volume and front-tracking methods are expected to perform the problem well for more complete case. 

Numerical Study on Aerodynamic Performances of CRH3 under Crosswind

2012 ◽  
Vol 215-216 ◽  
pp. 992-997
Author(s):  
Hong Yuan Su ◽  
Ming Li ◽  
Dong Ping Wang ◽  
Feng Liu
Keyword(s):  
High Speed ◽  
Numerical Study ◽  
Lateral Force ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Aerodynamic Properties ◽  
Aerodynamic Performances ◽  
Volume Method ◽  
Incompressible Navier Stokes Equation ◽  
Multiple Units

Based on 3D steady and incompressible Navier-Stokes equation and standard k-ε turbulent model, numerical calculation for the aerodynamic properties of EMU (Electric Multiple Units) CRH3 (China Railway High-Speed 3)running in crosswind were carried out by finite volume method. Aerodynamic performances of EMU CRH3 were analyzed and compared, when the EMU was running in different speed and under the crosswinds of different velocity. The research showed that with the change of speed of train and crosswind, the surface pressure and aerodynamic forces altered according to a certain rule. Compared with the drag, the change of lift and lateral force caused by the increase of crosswind were more serious. When the speed of train was constant of 200km/h, 250km/h and 300km/h, the drag of train increased by 26.7%, 20.4% and 19.8% respectively as the speed of crosswind increased from 12.5m/s to 30m/s, the lift of train increased by 340.7%, 331.7% and 337.1% respectively, and the lateral force of train increases by 296.3%, 266.0% and 150.2% respectively. As the speed of crosswind increases, the increase of drag caused by the acceleration of train is more serious than lift and lateral force.

Turbulence Models Performance Assessment for Pressure Prediction during Cylinder Water Entry

2012 ◽  
Vol 224 ◽  
pp. 225-229 ◽  
Author(s):  
Bao Dong Guo ◽  
Pei Qing Liu ◽  
Qiu Lin Qu ◽  
Yue Li Cui
Keyword(s):  
Stokes Equations ◽  
Turbulence Models ◽  
Water Entry ◽  
Navier Stokes ◽  
Engineering Practice ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
Dynamic Mesh Technique ◽  
Volume Method ◽  
Mesh Technique

Numerical simulations of two-dimensional cylinder free droping into water are presented based on volume of fluid (VOF) method and dynamic mesh technique. Solutions with a time-accurate finite-volume method (FVM) were generated based on the unsteady compressible ensemble averaged Navier-Stokes equations for the air and the unsteady incompressible ensemble averaged Navier-Stokes equations for the water. Computed pressure histories of the cylinder were compared with experimentally measured values. The performance of various turbulence models for pressure prediction was assessed. The results indicate that Realizable k-epsilon model with Enhanced Wall Treatment is the best choice for engineering practice.

ON CHAOTIC BEHAVIORS OF INCOMPRESSIBLE FLUID FLOWS IN TRIANGULAR DRIVEN CAVITIES

2005 ◽  
Vol 15 (10) ◽  
pp. 3103-3118 ◽  
Author(s):  
SONG WANG
Keyword(s):  
Incompressible Fluid ◽  
Stokes Equations ◽  
Initial Conditions ◽  
Fluid Flows ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Different Depths ◽  
Incompressible Fluid Flows ◽  
Volume Method

In this paper we investigate numerically chaotic behaviors of incompressible fluid flows at large Reynolds numbers in triangular driven cavities. The problem is first formulated as incompressible Navier–Stokes equations with appropriate boundary and initial conditions. The equations are then solved numerically by an exponentially fitted finite volume method for various Reynolds numbers up to 107. Numerical experiments on flows in triangular cavities with different depths are performed. The numerical results show clearly that the transitions of the flows from lamina to turbulence/chaos follow some conventional routes to chaos.

scholarly journals Prediksi Hambatan Kapal dengan Menggunakan Metode Overset Mesh pada Kapal Planing Hull

2020 ◽  
Vol 4 (1) ◽  
pp. 24-34
Author(s):  
Abubakar Fathuddiin ◽  
Samuel Samuel ◽  
Kiryanto Kiryanto ◽  
Aulia Widyandari
Keyword(s):  
Finite Volume Method ◽  
Finite Volume ◽  
Volume Of Fluid ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Ship Resistance ◽  
High Speeds ◽  
Mesh Method ◽  
Reynolds Averaged Navier Stokes ◽  
Volume Method

ABSTRAKPrediksi hambatan kapal tipe planing lebih rumit dibanding dengan tipe displacement, hal ini disebabkan oleh gaya hidrodinamis yang lebih dominan pada bagian bawah kapal. Karakteristik hambatan kapal tipe planing sangat dipengaruhi oleh gerakan trim dan heave. Selain itu, bentuk hullform juga mempengaruhi hambatan kapal; seperti sudut dead-rise, chine, strip, stephull, dan lain-lain. Solusi untuk memprediksi hambatan kapal dengan menggunakan Finite Volume Method (FVM). Persamaan RANS (Reynolds- Averaged Navier-Stokes) dengan model turbulensi k-ε untuk memprediksi aliran turbulen dan Volume of Fluid (VOF) untuk mempresentasikan aliran 2 fasa. Pada penelitian ini digunakan metode overset mesh untuk memprediksi hambatan kapal agar mendapatkan akurasi yang baik. Hasil simulasi hambatan menunjukkan trend yang baik. Pada kecepatan tinggi, prediksi hambatan tidak memiliki hasil yang baik. Solusi yang ditawarkan pada Numerical ventilation problem (NVP) adalah dengan menggunakan metode phase replacement.Kata kunci: CFD, planing hull, RANS, overset mesh, NVP ABSTRACTThe prediction of planing hull resistance is more complicated than the displacement hull. It is caused by the more dominant hydrodynamic force at the bottom of the ship. The planing hull resistance characteristics are strongly influenced by trim and heave movements. In addition, the shape of the hullform also affects the ship's resistance, such as dead-rise angle, chine, strip, stephull, and others. The solution to predict ship resistance is by using the Finite Volume Method (FVM). RANS (Reynolds-Averaged Navier-Stokes) equation k-ε turbulence model was used to predict turbulent flow and Volume of Fluid (VOF) to present 2 phase flow. In this study, the overset mesh method was used to predict ship resistance in order to get good accuracy. Resistance simulation results showed a good trend. At high speeds, the prediction of resistance did not have good results. The solution offered in the Numerical ventilation problem (NVP) was to use the phase replacement method.Keywords: CFD, planing hull, RANS, overset mesh, NVP

scholarly journals Validation and Verification of CFD Prediction of Fluid Flow of a Submerged Vertical Round Jet

2018 ◽  
Vol 3 (2) ◽  
pp. 113-121
Author(s):  
Nurul Hasan ◽  
Ahmed Oliur Rahman ◽  
Md. Shah Alam
Keyword(s):  
Symmetric Domain ◽  
Navier Stokes ◽  
Computational Error ◽  
Navier Stokes Equation ◽  
Validation And Verification ◽  
Fluent Software ◽  
Computational Fluid Dynamics Cfd ◽  
Volume Method ◽  
Grid Independence ◽  
Better Than

This paper presents a step by step verification and validation process of a vertical round submerged jet into a cylindrical bath. Taking advantage of the axi-symmetric domain, Navier-Stokes equation of primary is solved by finite volume method (FVM) using commercial computational fluid dynamics, CFD (Fluent) software. For verification and to minimise the computational error, step by step grid independence tests were performed. For validation, experimental data was produced using laser Doppler velocimetry (LDV). Among the turbulence model,  SST was found to predict the flow behaviour better than k-e-  realization or RSM models. 

scholarly journals A Numerical Study of Spray Strips Analysis on Fridsma Hull Form

Fluids ◽  
2021 ◽  
Vol 6 (11) ◽  
pp. 420
Author(s):  
Samuel ◽  
Andi Trimulyono ◽  
Parlindungan Manik ◽  
Deddy Chrismianto
Keyword(s):  
Fluid Dynamics ◽  
Numerical Study ◽  
Numerical Approach ◽  
Navier Stokes ◽  
Total Resistance ◽  
Navier Stokes Equation ◽  
Computational Fluid Dynamics Cfd ◽  
Wetted Surface Area ◽  
Volume Method ◽  
Dynamics Problems

Spray strips are deflectors added to the hull to reduce the Wetted Surface Area (WSA). The reduced WSA will decrease the total ship drag caused by the deflection of the spray strip installation. The research aimed to predict the function of the spray strip to improve ship performance using Computational Fluid Dynamics (CFD). The numerical approach in this study used the Finite Volume Method (FVM) with the RANS (Reynolds-averaged Navier–Stokes) equation to solve fluid dynamics problems. VOF (Volume of Fluid) was used to model the water and air phases. The results of this study indicated that the number of spray strips would have a significant effect compared to without using a spray strip. Spray strips with three strips could reduce the total resistance by 4.9% at Fr 1.78. Spray strips would increase the total resistance value by 2.1% at low speeds. Spray strips were effective for reducing total resistance at Fr > 1 or the planing mode conditions. The total resistance prediction used three suggestion profiles with the best performance to reduce total resistance by 6.0% at Fr 1.78.

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