Modeling and computation of the cavitating flow in injection nozzle holes

2015 ◽  
Vol 06 (01) ◽  
pp. 1550003 ◽  
Author(s):  
Hatem Kanfoudi ◽  
Ridha Zgolli
Keyword(s):  
Transport Equation ◽  
Source Term ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Variable Density ◽  
Navier Stokes ◽  
Physical Parameters ◽  
Cavitating Flows ◽  
Navier Stokes Equations ◽  
Injection Nozzle

Cavitating flows inside a diesel injection nozzle hole were simulated using a mixture model. A two-dimensional (2D) numerical model is proposed in this paper to simulate steady cavitating flows. The Reynolds-averaged Navier–Stokes equations are solved for the liquid and vapor mixture, which is considered as a single fluid with variable density and expressed as a function of the vapor volume fraction. The closure of this variable is provided by the transport equation with a source term Transport-equation based methods (TEM). The processes of evaporation and condensation are governed by changes in pressure within the flow. The source term is implanted in the CFD code ANSYS CFX. The influence of numerical and physical parameters is presented in detail. The numerical simulations are in good agreement with the experimental data for steady flow.

A NUMERICAL MODEL TO SIMULATE THE CAVITATING FLOWS

2011 ◽  
Vol 02 (03) ◽  
pp. 277-297 ◽  
Author(s):  
HATEM KANFOUDI ◽  
RIDHA ZGOLLI
Keyword(s):  
Single Phase ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Computer Time ◽  
Variable Density ◽  
Navier Stokes ◽  
Engineering Practice ◽  
Physical Parameters ◽  
Cavitating Flows ◽  
Flow Models

The object of this paper is to propose a model to simulate steady and unsteady cavitating flows. In the engineering practice, cavitation flow is often modeled as a single-phase flow (mixture), where the cavitation area is handled as an area with the pressure lower than the vapor pressure. This approach always leads to the result, and the requirement of computer time is many times lower in comparison with multiphase flow models. The Reynolds-averaged Navier–Stokes equations are solved for the mixture of liquid and vapor, which is considered as a single-phase with variable density. The vaporization and condensation processes are controlled by barocline low. A transport equation with source terms is implanted in the code Computational Fluid Dynamics (CFD) to compute the volume fraction of the vapor. The CFD code used is ANSYS CFX. The influence of numerical and the physical parameters are presented. The numerical results are compared to previous experimental measures. For steady flow, a SST turbulence model is adopted and LES for the unsteady flow.

scholarly journals Numerical investigation of an unsteady nanofluid flow with magnetic and suction effects to the moving upper plate

2020 ◽  
Vol 12 (2) ◽  
pp. 168781402090358 ◽  
Author(s):  
Muhammad Shuaib ◽  
Abbas Ali ◽  
Muhammad Altaf Khan ◽  
Aatif Ali
Keyword(s):  
Numerical Investigation ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Nonlinear Partial Differential Equations ◽  
Variable Magnetic Field ◽  
Navier Stokes ◽  
Physical Parameters ◽  
Nanofluid Flow ◽  
Navier Stokes Equations ◽  
Nicolson Scheme

The recent work provides the numerical investigation of an unsteady viscous nanofluid flow between two porous plates under the effect of variable magnetic field and suction/injection. Navier Stokes equations are modeled to study the hydrothermal properties of four different nanoparticles copper [Formula: see text], silver [Formula: see text], aluminum oxide [Formula: see text], and titanium oxide [Formula: see text]. The resultant nonlinear partial differential equations, governing the viscous fluid flow, are solved numerically using Crank–Nicolson scheme. The effect of important physical parameters such as volume fraction, magnetic strength, and porosity parameter are shown both graphically and in tabular form. It is found that due to the greatest thermal diffusivity for nanofluid [Formula: see text], comparatively the velocity increases more rapidly with the increasing value of volume fraction. Due to this effect, it is preferred to use nanofluid [Formula: see text] for transportation purposes.

Combined Marangoni and buoyancy convection in a porous annular cavity filled with Ag-MgO/water hybrid nanofluid

2021 ◽  
Vol 17 ◽  
Author(s):  
B. Kanimozhi ◽  
M. Muthtamilselvan ◽  
Qasem M. Al-Mdallal ◽  
Bahaaeldin Abdalla
Keyword(s):  
Magnetic Field ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Axial Magnetic Field ◽  
Vertical Wall ◽  
Navier Stokes ◽  
Hybrid Nanofluid ◽  
Radial Magnetic Field ◽  
Navier Stokes Equations ◽  
Buoyancy Convection

Background: This article numerically examines the effect of buoyancy and Marangoni convection in a porous enclosure formed by two concentric cylinders filled with Ag-MgO water hybrid nanofluid. The inner wall of the cavity is maintained at a hot temperature and the outer vertical wall is considered to be cold. The adiabatic condition is assumed for other two boundaries. The effect of magnetic field is considered in radial and axial directions. The Brinkman-extended Darcy model has been adopted in the governing equations. Methods: The finite difference scheme is employed to work out the governing Navier-Stokes equations. The numerically simulated outputs are deliberated in terms of isotherms, streamlines, velocityand average Nusselt number profiles for numerous governing parameters. Results: Except for a greater magnitude of axial magnetic field, our results suggest that the rate of thermal transport accelerates as the nanoparticle volume fraction grows.Also, it is observed that there is an escalation in the profile of average Nusselt numberwith an enhancement in Marangoni number. Conclusion: Furthermore, the suppression of heat and fluid flow in the tall annulus is mainly due to the radial magnetic field whereas in shallow annulus, the axial magnetic field profoundly affects the flow field and thermal transfer.

Magnetic field effects on the slip velocity and temperature jump of nanofluid forced convection in a microchannel

2015 ◽  
Vol 230 (11) ◽  
pp. 1921-1936 ◽  
Author(s):  
Arash Karimipour ◽  
Masoud Afrand
Keyword(s):  
Magnetic Field ◽  
Forced Convection ◽  
Slip Velocity ◽  
Temperature Jump ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Computer Code ◽  
Navier Stokes ◽  
Magnetic Field Effects ◽  
Navier Stokes Equations

Forced convection of water–Cu nanofluid in a two-dimensional microchannel is studied numerically. The microchannel wall is divided into three parts. The entry and exit ones are kept insulated while the middle one has more temperature than the inlet fluid. The whole of microchannel is under the influence of a magnetic field with uniform strength of B0. Slip velocity and temperature jump are involved along the microchannel walls for different values of slip coefficient such as B = 0.001, B = 0.01, and B = 0.1 for Re = 10, Re = 50, and Re = 100. Navier–Stokes equations are discretized and numerically solved by a developed computer code in FORTRAN. Results are presented as the velocity, temperature, and Nusselt number profiles. Moreover, the effect of magnetic field on slip velocity and temperature jump is investigated for the first time in the present work. Larger Hartmann number, Reynolds number, and volume fraction correspond to more heat transfer rate; however, the effects of Ha and ϕ are more significant at higher Re.

scholarly journals Natural convection melting of nano-enhanced phase change material in a cavity with finned copper profile

2018 ◽  
Vol 240 ◽  
pp. 01006 ◽  
Author(s):  
Nadezhda Bondareva ◽  
Mikhail Sheremet
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Stokes Equations ◽  
Volume Fraction ◽  
Melting Process ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
Dimensional Approximation ◽  
Change Material

Present study is devoted to numerical simulation of heat and mass transfer inside a cooper profile filled with paraffin enhanced with Al2O3 nanoparticles. This profile is heated by the heat-generating element of constant volumetric heat flux. Two-dimensional approximation of melting process is described by the Navier-Stokes equations in non-dimensional variables such as stream function, vorticity and temperature. The enthalpy formulation has been used for description of the heat transfer. The influence of volume fraction of nanoparticles and intensity of heat generation on melting process and natural convection in liquid phase has been studied.

NUMERICAL ANALYSIS OF A TWO PHASE FLOW MODEL

2012 ◽  
Vol 09 (03) ◽  
pp. 1250036 ◽  
Author(s):  
MOHAMED ABDELWAHED ◽  
MOHAMED AMARA
Keyword(s):  
Stokes Equations ◽  
Mixed Finite Element ◽  
Mixed Finite Element Method ◽  
Time Discretization ◽  
Variable Density ◽  
Navier Stokes ◽  
Two Phase ◽  
Navier Stokes Equations ◽  
Quality Of Water ◽  
Coupling Characteristics

Due to ever increasing water demand, the preservation of water quality is becoming a very important issue. Eutrophication is amongst the particular problems threatening the quality of water. This paper begins with presenting a mathematical model for aeration process in lake used to combat water eutrophication. Two phases are numerically simulated to study the injected air effect on water by using a corrected one phase model described by Navier–Stokes equations with variable density and viscosity representing the mixture. This model is numerically studied by coupling characteristics scheme for time discretization and mixed finite element method for space approximation. An error estimates in space and time for the velocity are obtained. Numerical results are given firstly in support of the mathematical analysis and secondly to simulate a real application case of the studied problem.

Computations of the Compressible Multiphase Flow Over the Cavitating High-Speed Torpedo

2003 ◽  
Vol 125 (3) ◽  
pp. 459-468 ◽  
Author(s):  
F. M. Owis ◽  
Ali H. Nayfeh
Keyword(s):  
High Speed ◽  
Multiphase Flows ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Multiphase System ◽  
System Of Equations ◽  
Cavitating Flows ◽  
Navier Stokes Equations ◽  
Compressible Multiphase Flow ◽  
Speed Flow

For high-speed cavitating flows, compressibility becomes significant in the liquid phase as well as in the vapor phase. In addition, the compressible energy equation is required for studying the effects of the propulsive jet on the cavity. Therefore, a numerical method is developed to compute cavitating flows over high-speed torpedoes using the full unsteady compressible Navier-Stokes equations. The multiphase system of equations is preconditioned for low-speed flow computations. Using the mass fraction form, we derive an eigensystem for both the conditioned and the nonconditioned system of equations. This eigensystem provides stability for the numerical discretization of the convective flux and increases the convergence rate. This method can be used to compute single as well as multiphase flows. The governing equations are discretized on a structured grid using an upwind flux difference scheme with flux limits. Single as well as multiphase flows are computed over a cavitating torpedo. The results indicate that the preconditioned system of equations converges rapidly to the required solution at very low speeds. The theoretical results are in good agreement with the measurements.

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