Numerical Simulation of the Fuel Oil Cooling Process in a Wrecked Ship

2006 ◽  
Vol 128 (6) ◽  
pp. 1390-1393 ◽  
Author(s):  
Jesús Manuel Fernández Oro ◽  
Carlos Santolaria Morros ◽  
Katia María Argüelles Díaz ◽  
Pedro Luis García Ybarra
Keyword(s):  
Numerical Simulation ◽  
Deep Sea ◽  
Sea Water ◽  
Fluid Dynamic ◽  
Characteristic Temperature ◽  
Thermal Conditions ◽  
Fuel Oil ◽  
Navier Stokes ◽  
Cooling Process ◽  
Order Of Magnitude

This work deals with a numerical simulation developed to predict the characteristic cooling times of a low-thermal diffusivity fuel oil confined in the tanks of a wrecked ship. A typical scenario has been introduced through the definition of tank geometries, physical boundary conditions (deep sea temperatures), and rheological properties of the fuel oil. The fluid dynamic behavior of the oil (free convection) inside the tanks, as well as the heat exchange with surrounding sea water has been simulated using a commercial code, FLUENT, which directly solves the Navier-Stokes set of equations, including energy. The purpose is focused on the prediction of both spatial and temporal evolution of the fuel oil characteristic temperature inside the tanks. The objective is to determine the deadline in which the asymptotic temperature curve of the fuel oil converges with deep sea thermal conditions. Inspectional analysis is also outlined, as a powerful tool to predict an order of magnitude in the cooling process.

Numerical Simulation of the Fuel-Oil Cooling Process in Wrecked Ship

2005 ◽  
Author(s):  
J. M. Ferna´ndez Oro ◽  
C. Santolaria Morros ◽  
K. M. Argu¨elles Di´az ◽  
P. L. Garci´a Ybarra
Keyword(s):  
Numerical Simulation ◽  
Deep Sea ◽  
Sea Water ◽  
Characteristic Temperature ◽  
Thermal Conditions ◽  
Fuel Oil ◽  
Navier Stokes ◽  
Cooling Process ◽  
Order Of Magnitude ◽  
Definition Of

This work deals with a numerical simulation developed to predict the characteristic cooling times of a low-thermal diffusivity fuel-oil confined in the tanks of a wrecked ship. A typical scenario has been introduced, through the definition of tanks geometries, physical boundary conditions (deep sea temperatures) and reological properties of the fuel-oil. The fluidynamic behaviour of the oil (forced convection) inside the tanks, as well as the heat exchange with surrounding sea water has been simulated throughout a commercial code, FLUENT, that solves directly the Navier-Stokes set of equations, including energy one. The purpose is focused on the prediction of both spatial and temporal evolution of the fuel-oil characteristic temperature inside the tanks. The final objective is placed on the determination of the deadline in which asymptotic temperature curve of the fuel-oil converges to deep sea thermal conditions. Inspectional analysis is also outlined, as a powerful tool to predict an order of magnitude in the cooling process.

scholarly journals Conjugate Heat Transfer Predictions for Subcooled Boiling Flow in a Horizontal Channel Using a Volume-of-Fluid Framework

2018 ◽  
Vol 140 (10) ◽  
Author(s):  
M. Langari ◽  
Z. Yang ◽  
J. F. Dunne ◽  
S. Jafari ◽  
J.-P. Pirault ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Turbulence Modeling ◽  
Fluid Dynamic ◽  
Computational Cost ◽  
Thermal Conditions ◽  
Nucleate Boiling ◽  
Volume Of Fluid ◽  
Navier Stokes ◽  
Mass Generation

Abstract The accuracy of computational fluid dynamic (CFD)-based heat transfer predictions have been examined of relevance to liquid cooling of IC engines at high engine loads where some nucleate boiling occurs. Predictions based on (i) the Reynolds Averaged Navier-Stokes (RANS) solution and (ii) large eddy simulation (LES) have been generated. The purpose of these simulations is to establish the role of turbulence modeling on the accuracy and efficiency of heat transfer predictions for engine-like thermal conditions where published experimental data are available. A multiphase mixture modeling approach, with a volume-of-fluid interface-capturing method, has been employed. To predict heat transfer in the boiling regime, the empirical boiling correlation of Rohsenow is used for both RANS and LES. The rate of vapor-mass generation at the wall surface is determined from the heat flux associated with the evaporation phase change. Predictions via CFD are compared with published experimental data showing that LES gives only slightly more accurate temperature predictions compared to RANS but at substantially higher computational cost.

Numerical Simulation on Flight Dynamic Characteristics of Elastic Wing Based on Gust Response

2013 ◽  
Vol 397-400 ◽  
pp. 378-383
Author(s):  
Wen Hui Dong ◽  
Chun Lei Yang ◽  
Yan Hui Li ◽  
Hong Guang Jia
Keyword(s):  
Numerical Simulation ◽  
Numerical Method ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Navier Stokes ◽  
Dynamic Problems ◽  
Aerodynamic Forces ◽  
Structural Dynamic ◽  
Navier Stokes Equations ◽  
Gust Response

In this paper, the numerical method was developed to flight dynamics characteristics of elastic wing under the action of the discrete gust. In this numerical method, the aerodynamic forces of the elastic wing were calculated by solving the unsteady Navier Stokes equations, and incorporating the grid velocity method to simulating the gust response of the typical NACA0006 airfoil to the step changes in the angle of attack of aircraft . it is shown in results that the calculated lift responses of the airfoil agree well with both the exact theoretical value and calculated value in reference. the elastic effect was considered with RayleighRitz method, so that the fluid dynamic,structural dynamic and flight dynamic problems can be coupled to solve. and AGARD445.6 elastic wing for the numerical simulation of the flight characteristics.

Non-stationary process characteristics of the gas outflow into a liquid

2019 ◽  
Vol 14 (2) ◽  
pp. 82-88
Author(s):  
M.V. Alekseev ◽  
I.S. Vozhakov ◽  
S.I. Lezhnin
Keyword(s):  
Numerical Simulation ◽  
Liquid Column ◽  
Gas Content ◽  
Liquid Lead ◽  
Gas Flows ◽  
Asymptotic Model ◽  
Process Characteristics ◽  
Significant Difference ◽  
Order Of Magnitude ◽  
Volume Method

A numerical simulation of the process of the outflow of gas under pressure into a closed container partially filled with liquid was carried out. For comparative theoretical analysis, an asymptotic model was used with assumptions about the adiabaticity of the gas outflow process and the ideality of the liquid during the oscillatory one-dimensional motion of the liquid column. In this case, the motion of the liquid column and the evolution of pressure in the gas are determined by the equation of dynamics and the balance of enthalpy. Numerical simulation was performed in the OpenFOAM package using the fluid volume method (VOF method) and the standard k-e turbulence model. The evolution of the fields of volumetric gas content, velocity, and pressure during the flow of gas from the high-pressure chamber into a closed channel filled with liquid in the presence of a ”gas blanket“ at the upper end of the channel is obtained. It was shown that the dynamics of pulsations in the gas cavity that occurs when the gas flows into the closed region substantially depends on the physical properties of the liquid in the volume, especially the density. Numerical modeling showed that the injection of gas into water occurs in the form of a jet outflow of gas, and for the outflow into liquid lead, a gas slug is formed at the bottom of the channel. Satisfactory agreement was obtained between the numerical calculation and the calculation according to the asymptotic model for pressure pulsations in a gas projectile in liquid lead. For water, the results of calculations using the asymptotic model give a significant difference from the results of numerical calculations. In all cases, the velocity of the medium obtained by numerical simulation and when using the asymptotic model differ by an order of magnitude or more.

scholarly journals Statistical Uncertainty of DNS in Geometries without Homogeneous Directions

2021 ◽  
Vol 11 (4) ◽  
pp. 1399
Author(s):  
Jure Oder ◽  
Cédric Flageul ◽  
Iztok Tiselj
Keyword(s):  
Channel Flow ◽  
A Priori ◽  
Time Integration ◽  
Navier Stokes ◽  
Statistical Uncertainty ◽  
Time Step ◽  
Order Of Magnitude ◽  
Averaging Time ◽  
The Individual ◽  
Time Required

In this paper, we present uncertainties of statistical quantities of direct numerical simulations (DNS) with small numerical errors. The uncertainties are analysed for channel flow and a flow separation case in a confined backward facing step (BFS) geometry. The infinite channel flow case has two homogeneous directions and this is usually exploited to speed-up the convergence of the results. As we show, such a procedure reduces statistical uncertainties of the results by up to an order of magnitude. This effect is strongest in the near wall regions. In the case of flow over a confined BFS, there are no such directions and thus very long integration times are required. The individual statistical quantities converge with the square root of time integration so, in order to improve the uncertainty by a factor of two, the simulation has to be prolonged by a factor of four. We provide an estimator that can be used to evaluate a priori the DNS relative statistical uncertainties from results obtained with a Reynolds Averaged Navier Stokes simulation. In the DNS, the estimator can be used to predict the averaging time and with it the simulation time required to achieve a certain relative statistical uncertainty of results. For accurate evaluation of averages and their uncertainties, it is not required to use every time step of the DNS. We observe that statistical uncertainty of the results is uninfluenced by reducing the number of samples to the point where the period between two consecutive samples measured in Courant–Friedrichss–Levy (CFL) condition units is below one. Nevertheless, crossing this limit, the estimates of uncertainties start to exhibit significant growth.

The inlet flow structure of a conceptual open-nose supersonic drone

2021 ◽  
pp. 095441002098304
Author(s):  
Eiman B Saheby ◽  
Xing Shen ◽  
Anthony P Hays ◽  
Zhang Jun
Keyword(s):  
Flow Structure ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Three Dimensional ◽  
Computational Fluid Dynamic Simulation ◽  
Navier Stokes ◽  
Ansys Fluent ◽  
Navier Stokes Equations ◽  
Aerodynamic Efficiency ◽  
Performance Effects

This study describes the aerodynamic efficiency of a forebody–inlet configuration and computational investigation of a drone system, capable of sustainable supersonic cruising at Mach 1.60. Because the whole drone configuration is formed around the induction system and the design is highly interrelated to the flow structure of forebody and inlet efficiency, analysis of this section and understanding its flow pattern is necessary before any progress in design phases. The compression surface is designed analytically using oblique shock patterns, which results in a low drag forebody. To study the concept, two inlet–forebody geometries are considered for Computational Fluid Dynamic simulation using ANSYS Fluent code. The supersonic and subsonic performance, effects of angle of attack, sideslip, and duct geometries on the propulsive efficiency of the concept are studied by solving the three-dimensional Navier–Stokes equations in structured cell domains. Comparing the results with the available data from other sources indicates that the aerodynamic efficiency of the concept is acceptable at supersonic and transonic regimes.

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