Mid-Profile Design and Numerical Simulation for Supercavitating Vehicle

2011 ◽  
Vol 422 ◽  
pp. 592-595
Author(s):  
Yu Tian Li ◽  
Yu Wen Zhang
Keyword(s):  
Numerical Simulation ◽  
Drag Reduction ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Supercavitating Vehicle ◽  
Profile Design ◽  
And Control ◽  
Curve Equation ◽  
Geometrical Equation ◽  
Better Than

Based on elliptic curve equation and G.V.Logvinovich cavity geometrical equation, the mid-profile of supercavitating vehicle was researched. The author uses Navier-Stokes equation and k-ε turbulence equation to simulate the designed geometry shape depending on structure grid. The beneficial results show that the mid-profile design for supercavitating vehicle is able to integrate and control the partial attached cavitating flow, and enable the cavity proximate shape to the elliptic shape. As a result, the cavitating reflow phenomenon influenced by tail nozzle contraction at the rear of the supercavitating vehicle could be mitigated, and in a certain range of curvature, the drag reduction performance is better than that of the cylindrical method. The research is able to effectively increase the fullness of the supercavitating vehicle in the mid-profile, and so it is quite superiority.

Numerical Simulation of Muzzle Flow Field of Gun Based on CFD

2013 ◽  
Vol 291-294 ◽  
pp. 1981-1984
Author(s):  
Zhang Xia Guo ◽  
Yu Tian Pan ◽  
Yong Cun Wang ◽  
Hai Yan Zhang
Keyword(s):  
Numerical Simulation ◽  
Flow Field ◽  
Stokes Equation ◽  
Wave Structure ◽  
Flow Fields ◽  
Single Equation ◽  
Navier Stokes ◽  
Turbulent Model ◽  
Navier Stokes Equation ◽  
Numerical Simulation Result

Gunpowder was released in an instant when the pill fly out of the shell during the firing, and then formed a complicated flow fields about the muzzle when the gas expanded sharply. Using the 2 d axisymmetric Navier-Stokes equation combined with single equation turbulent model to conduct the numerical simulation of the process of gunpowder gass evacuating out of the shell without muzzle regardless of the pill’s movement. The numerical simulation result was identical with the experimental. Then simulated the evacuating process of gunpowder gass of an artillery with muzzle brake. The result showed complicated wave structure of the flow fields with the muzzle brake and analysed the influence of muzzle brake to the gass flow field distribution.

scholarly journals A note on time-fractional Navier–Stokes equation and multi-Laplace transform decomposition method

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Hassan Eltayeb ◽  
Imed Bachar ◽  
Yahya T. Abdalla
Keyword(s):  
Numerical Simulation ◽  
Approximate Solution ◽  
Decomposition Method ◽  
Adomian Decomposition Method ◽  
Approximate Solutions ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equation ◽  
Adomian Decomposition ◽  
Stokes Problems

Abstract In this study, the double Laplace Adomian decomposition method and the triple Laplace Adomian decomposition method are employed to solve one- and two-dimensional time-fractional Navier–Stokes problems, respectively. In order to examine the applicability of these methods some examples are provided. The presented results confirm that the proposed methods are very effective in the search of exact and approximate solutions for the problems. Numerical simulation is used to sketch the exact and approximate solution.

Numerical Simulation Calculation of Hydroplane Direct Route Motion Based on FLUENT

2012 ◽  
Vol 569 ◽  
pp. 368-375
Author(s):  
Yu Qin ◽  
Xiao Liang ◽  
Jia Ning Zhang
Keyword(s):  
Numerical Simulation ◽  
Performance Prediction ◽  
Dynamic Pressure ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Velocity Change ◽  
Direct Route ◽  
Field Situation ◽  
Simulation Calculation

Aiming at hydrodynamic performance prediction for hydroplane motion, numerical simulation calculation for direct route motion of a hydroplane was carried out under FLUENT software platform by using VOF method and RNG k-ε model and solving Navier-Stokes equation. Evolution of ship resistance was obtained as the velocity change, and flow field situation and dynamic pressure variation of hydroplane hull bottom were reflected intuitively. By comparing the results of FLUENT calculation and ship model experiment and theoretical estimation, analyzing, especially wake current, it was verified that numerical simulation calculation of hydroplane direct route motion and hydrodynamic performance prediction based on FLUENT are feasible and precise enough.

Computerized Fluid Dynamic Study of Parameter Effects on the Performance of Coaxial Propellers

2020 ◽  
Vol 17 (7) ◽  
pp. 3237-3242
Author(s):  
Young-Tae Kim ◽  
Chang Hwan Park ◽  
Hak Yoon Kim
Keyword(s):  
Pitch Angle ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Steady State Condition ◽  
Performance Variation ◽  
Air Vehicle ◽  
Program Star ◽  
And Control

The computerized fluid dynamic (CFD) analysis was performed for 1.8 m diameter coaxial propellers to be applied to the multi-copter type Personal Air Vehicle (PAV) having conceptually 600 kg of Maximum Take-Off Weight (MTOW). Methods/Statistical analysis: Using the commercial CFD program STAR-CCM+ (13.03.11), the coaxial propellers were analyzed at the same RPM under the steady state condition. The three-dimensional Compressible Reynolds Mean Navier-Stokes equation was applied and the Moving Reference Frame (MRF) technique was used. With the optimum single pitch angle of upper propeller, the lower propeller’s pitch was changed for the varying propeller spacing to identify the performance variation and the interference effect. The lower propeller has to be different pitch setting other than the upper propeller’s optimum pitch angle because of the interfered flow effect between propellers. The propeller spacing is not so sensitive to efficiency if the spacing is more than 0.25 of propeller diameter. Study shows that the identified pitches and spacing of coaxial propellers are essential for designing the configuration and control of multi-copter type PAV which uses variable pitch propellers for safety and efficiency.

Direct Numerical Simulation and RANS Comparison of Turbulent Convective Heat Transfer in a Staggered Ribbed Channel With High Blockage

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Luca Marocco ◽  
Andrea Franco
Keyword(s):  
Numerical Simulation ◽  
Direct Numerical Simulation ◽  
Convective Flow ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Reference Solution ◽  
Ribbed Channel ◽  
Sst Model ◽  
Rans Turbulence Models ◽  
Better Than

A turbulent convective flow of an incompressible fluid inside a staggered ribbed channel with high blockage at ReH ≈ 4200 is simulated with direct numerical simulation (DNS) and Reynolds-averaged Navier–Stokes (RANS) techniques. The DNS results provide the reference solution for comparison of the RANS turbulence models. The k–ε realizable, k–ω SST, and v2¯–f model are accurately analyzed for their strengths and weaknesses in predicting the flow and temperature field for this geometry. These three models have been extensively used in literature to simulate this configuration and boundary conditions but with discordant conclusions upon their performance. The v2¯–f model performs much better than the k–ε realizable while the k–ω SST model results to be inadequate.

Numerical Simulation of Aerodynamic Force on Solar Panels

2013 ◽  
Author(s):  
Aklilu T. G. Giorges ◽  
Guillermo J. Amador ◽  
Kevin Caravati ◽  
Joseph Goodman
Keyword(s):  
Numerical Simulation ◽  
Aerodynamic Force ◽  
Navier Stokes ◽  
Solar Photovoltaic ◽  
Solar Panels ◽  
Navier Stokes Equation ◽  
Local Conditions ◽  
Photovoltaic Panel ◽  
Solar Arrays ◽  
Turbulent Process

Significant cost reductions for solar photovoltaic systems can be realized through aerodynamic design improvements for ground mounted and rooftop installations. Current practices in the solar industry are based on ASCE-7 codes created for buildings and do not fully account for wind reduction strategies. Numerical simulation is one of the tools that can be used to evaluate wind loads and improve system designs while maintaining reliability and durability. As a first order analysis, we have numerically simulated a solar photovoltaic panel as a flat plate with an aspect ratio of 0.5, which includes the simulation of turbulence experienced by panels. The flow is simulated using the incompressible Navier-Stokes equation and the turbulent process is simulated using k–ε model. The numerical model and boundary conditions are derived from similar experimental wind tunnel experiments. The aerodynamic force is calculated from the integration of the normal and tangential pressure forces. The result of the numerical simulation shows that the wind load on a solar panel can be successfully simulated numerically and the simulation data can be used to evaluate redesigns of the system, allowing for the effective customization of solar arrays based on local conditions.

Moisture Transport and Shrinkage in Concrete at early Age

2012 ◽  
Vol 174-177 ◽  
pp. 232-235 ◽  
Author(s):  
Ling Yun Meng
Keyword(s):  
Numerical Simulation ◽  
Stokes Equation ◽  
Lattice Gas ◽  
Environmental Scanning Electron Microscopy ◽  
Navier Stokes ◽  
Early Age ◽  
Weak Zone ◽  
Navier Stokes Equation ◽  
Moisture Flow ◽  
Lattice Gas Automata

Abstract: The moisture flow and drying of porous media, such as concrete, is tackled through the Navier-Stokes equation, where the Navier-Stokes equation is considered as the link between the theory of fluid flow, Acoustic Emission (AE) experiments on cracking (sound propagation based on the wave equation) and Lattice Gas Automata, (LGA) being a numerical simulation of the Navier-Stokes equation. Early age cracking in the ITZ is induced by using the moisture flow as the only “load” that causes cracking due to drying shrinkage volume changes in Environmental Scanning Electron Microscopy (ESEM) tests. An attempt is made to link and compare experimental results conducted by means of AE and ESEM to the results of 2-D LGA numerical simulation. Lattice Gas Automata (FHP model) is used as a basis to generate a new model for drying of porous medium. Special emphasis in a model creation is given to the Interface Transition Zone (ITZ), between aggregate and cement paste, because of the early crack initiation in this highly porous and strength-weak zone.

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