Fluid-Structure Simulations for a 2D Fire Applications

2005 ◽  
Author(s):  
Wei Xie ◽  
Changsong Luo ◽  
Paul E. DesJardin
Keyword(s):  
Mass Transfer ◽  
Level Set ◽  
Stokes Equations ◽  
Numerical Algorithms ◽  
Thermal Response ◽  
Navier Stokes ◽  
Fire Plume ◽  
Fluid Structure ◽  
Local Boundary ◽  
Level Set Function

This study is on the development of numerical algorithms and models for simulation of a structure response in a fire. The flow field from the fire plume is modeled using the 2D Navier-Stokes equations supplemented with a transport equation for thermal energy and solved using a vorticity-streamfunction approach. Coupling of the fluid to the FEM based structure model is based on the use of a level set method describing the structure geometry in the fluid domain. The level set function allows for computation of normal gradients at the fluid-solid interface to enforce local boundary conditions of heat and mass transfer at prescribed fluid-structure coupling time increments. Numerical simulations of a two-dimensional composite cantilever beam subject to convection heat loading from a fire plume are presented requiring coupling of both the thermal and mass transfer processes at the fluid-structure interface. Results are presented showing the thermal response of a composite beam to a fire plume and the sensitivity of the heating to fire location.

Simulation of Wave-Body Interaction Using a Single-Phase Level Set Function in the SWENSE Method

2013 ◽  
Author(s):  
Gabriel Reliquet ◽  
Aurélien Drouet ◽  
Pierre-Emmanuel Guillerm ◽  
Erwan Jacquin ◽  
Lionel Gentaz ◽  
...  
Keyword(s):  
Free Surface ◽  
Level Set Method ◽  
Level Set ◽  
Single Phase ◽  
Stokes Equations ◽  
Flow Theory ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Level Set Function ◽  
Set Function

The purpose of this paper is to present combination of the SWENSE (Spectral Wave Explicit Navier-Stokes Equations – [1]) method — an original method to treat fully nonlinear wave-body interactions — and a free surface RANSE (Reynolds Averaged Navier-Stokes Equations) solver using a single-phase Level Set method to capture the interface. The idea is to be able to simulate wave-body interactions under viscous flow theory with strong deformations of the interface (wave breaking in the vicinity of the body, green water on ship decks…), while keeping the advantages of the SWENSE scheme. The SWENSE approach is based on a physical decomposition by combining incident waves described by a nonlinear spectral scheme based on potential flow theory and an adapted Navier-Stokes solver where only the diffracted part of the flow is solved, incident flow parameters seen as forcing terms. In the single-phase Level Set method [2, 3], the air phase is neglected. Thus, only the liquid phase is solved considering a fluid with uniform properties. The location of the free surface is determined by a Level Set function initialised as the signed distance. The accuracy of simulation depends essentially on the pressure scheme used to impose free surface dynamic boundary condition. Comparisons of numerical results with experimental and numerical data for US navy combatant DTMB 5415 in calm water and in head waves are presented.

Interface Tracking With a Coupled Level Set /VOF/Ghost Fluid Method: Application to Jet Atomization

2007 ◽  
Author(s):  
T. Me´nard ◽  
A. Berlemont
Keyword(s):  
Level Set ◽  
Stokes Equations ◽  
Level Set Methods ◽  
Mass Conservation ◽  
Navier Stokes ◽  
Interface Tracking ◽  
Ghost Fluid Method ◽  
Level Set Function ◽  
Wide Range ◽  
Break Up

We are here concerned by the primary break-up of a jet: a lot of topological changes occur and the Level Set Method thus appears well designed for our purpose. To describe the interface discontinuities, we use the Ghost Fluid Method (GFM) and a projection method is used to solve incompressible Navier-Stokes equations that are coupled to a transport equation for the level set function. The main drawback of level set methods is that numerical computations in the re-distancing algorithm can generate mass loss in under-resolved regions. To improve mass conservation extension of the method can be developed, namely a coupling between VOF and Level Set. In order to illustrate the abilities of the Level Set/VOF/Ghost Fluid method for interface tracking, we present a 3D simulation of the primary atomization zone of a turbulent liquid jet. The turbulence initiates some perturbations on the liquid surface, that are enhanced by the mean shear and break-up occurs. The generated liquid parcels show a wide range of shapes. Particular behaviors such ligament detachments, droplet formations and break up are described.

Level-Set Computations of Free Surface Rotational Flows

2005 ◽  
Vol 127 (6) ◽  
pp. 1111-1121 ◽  
Author(s):  
Giuseppina Colicchio ◽  
Maurizio Landrini ◽  
John R. Chaplin
Keyword(s):  
Free Surface ◽  
Numerical Method ◽  
Level Set ◽  
Stokes Equations ◽  
Vertical Surface ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Two Fluids ◽  
Level Set Function ◽  
Rotational Flows

A numerical method is developed for modeling the violent motion and fragmentation of an interface between two fluids. The flow field is described through the solution of the Navier-Stokes equations for both fluids (in this case water and air), and the interface is captured by a Level-Set function. Particular attention is given to modeling the interface, where most of the numerical approximations are made. Novel features are that the reintialization procedure has been redefined in cells crossed by the interface; the density has been smoothed across the interface using an exponential function to obtain an equally stiff variation of the density and of its inverse; and we have used an essentially non-oscillatory scheme with a limiter whose coefficients depend on the distance function at the interface. The results of the refined scheme have been compared with those of the basic scheme and with other numerical solvers, with favorable results. Besides the case of the vertical surface-piercing plate (for which new laboratory measurements were carried out) the numerical method is applied to problems involving a dam-break and wall-impact, the interaction of a vortex with a free surface, and the deformation of a cylindrical bubble. Promising agreement with other sources of data is found in every case.

A Level Set Method for Simulation of Coalescence of Droplets

2005 ◽  
Author(s):  
A. Salih ◽  
S. Ghosh Moulic
Keyword(s):  
Surface Tension ◽  
Level Set Method ◽  
Level Set ◽  
Stokes Equations ◽  
Surface Tension Force ◽  
Tension Force ◽  
Staggered Grid ◽  
Navier Stokes ◽  
Level Set Function ◽  
Set Function

In the present paper, we discuss a numerical method based on the level set algorithm to simulate two-phase fluid flow systems. Surface tension force at the fluid interface is implemented through the CSF model of Brackbill et al. [1]. The incompressible Navier-Stokes equations were solved on a staggered grid using an explicit projection method. A fifth-order WENO [2] scheme was used for advancing the level set function. We improved the implementation of WENO scheme by staggering the level set function. The Navier-Stokes part of the code was validated by computing the standard lid-driven cavity flow and the free surface part of the code was validated by advecting the interface in a prescribed velocity field. The Young-Laplace law for a static drop has been verified to validate the implementation of surface tension force. We simulated the coalescence of two drops under zero-gravity condition and evaluated the mass conservation property of the level set method.

scholarly journals Numerical Modeling of the Motion and Interaction of a Droplet of an Inkjet Printing Process with a Flat Surface

2021 ◽  
Vol 11 (2) ◽  
pp. 527
Author(s):  
Tim Tofan ◽  
Harald Kruggel-Emden ◽  
Vytautas Turla ◽  
Raimondas Jasevičius
Keyword(s):  
Level Set ◽  
Stokes Equations ◽  
Field Method ◽  
Phase Field Method ◽  
Navier Stokes ◽  
Stable Form ◽  
Fluid Interface ◽  
Velocity Change ◽  
Navier Stokes Equations ◽  
Inkjet Printhead

The numerical simulation and analysis of the ejection of an ink droplet through a nozzle as well its motion through air until its contact with a surface and taking up of a stable form is performed. The fluid flow is modeled by the incompressible Navier–Stokes equations with added surface tension. The presented model can be solved using either a level set or a phase field method to track the fluid interface. Here, the level set method is used to determinate the interface between ink and air. The presented work concentrates on the demonstration how to check the suitability of ink for inkjet printhead nozzles, for instance, for the use in printers. The results such as velocity, change of size, and volume dependence on time of an ink droplet are presented. Recommendations for the use of specific inks are also given.

scholarly journals Choice and Limits of a Fluid Model for the Numerical Study in Dynamic Fluid Structure Interaction Problems

2003 ◽  
Author(s):  
Jean Franc¸ois Sigrist ◽  
Christian Laine ◽  
Dominique Lemoine ◽  
Bernard Peseux
Keyword(s):  
Stokes Equations ◽  
Numerical Study ◽  
Fluid Model ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Linear Solution ◽  
Fluid Structure ◽  
Design Engineers ◽  
Inviscid Incompressible Fluid ◽  
Basic Fluid

This paper is related to the study of a nuclear propulsion reactor prototype for the French Navy. This prototype is built on ground and is to be dimensioned toward seismic loading. The dynamic analysis takes the coupled fluid structure analysis into account. The basic fluid models used by design engineers are inviscid incompressible or compressible. The fluid can be described in a bidimensional by slice or a three-dimensional approach. A numerical study is carried out on a generic problem for the linear FSI dynamic problem. The results of this study are presented and discussed. As a conclusion, the three-dimensional inviscid incompressible fluid appears to be the best compromise between the description of physical phenomena and the cost of modeling. The geometry of the reactor is such that large displacements of the structure in the fluid can occur. Therefore, the linearity hypothesis might not be longer valid. The case of large amplitude imposed oscillating motion of a cylinder in a confined fluid is numerically studied. A CFD code is used to investigate the fluid behavior solving the NAVIER-STOKES equations. The forces induced on the cylinder by the fluid are computed and compared to the linear solution. The limit of the linear model can then be exhibited.

scholarly journals NUMERICAL CALCULATION OF VELOCITY FIELDS FOR VISCO-ELASTIC MATERIALS IN CYLINDRICAL CHANNELS

2019 ◽  
pp. 19-28
Author(s):  
Ekaterina Valer'evna Fomenko ◽  
Albert Hamed-Harisovich Nugmanov ◽  
Thi Sen Nguyen ◽  
Aleksanyan Igor Yuryevich Aleksanyan
Keyword(s):  
Mass Transfer ◽  
Heat And Mass Transfer ◽  
Stokes Equations ◽  
Radiation Power ◽  
Wheat Gluten ◽  
Internal Heat ◽  
Velocity Fields ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Suggested Approach

The article touches upon the application of the numerical finite difference method for solving Navier-Stokes equation in case of one-dimensional problem of passing a cooled viscoelastic material inside circular nozzles. There have been analyzed the specific features of using the method and presented the results of its application. The object of study was not chosen at random, because viscous properties of raw gluten are variable and depend on the temperature, chemical composition and properties of the feedstock. Working not properly with the object of research (phenomenon, process), but with its model helps to characterize its properties and behavior in various situations relatively quickly and without significant costs. The need to identify patterns of internal heat and mass transfer, which is based on studying the kinetics of the process, is obvious for physic-mathematical modeling of heat and mass transfer processes of wheat gluten granulation, in particular, analyzing the mechanism of moisture removal during its drying under radiation power supply. The results of the conducted research are consistent with the available data on the subject, and the suggested approach to solving the problem of choosing rational hydrodynamic regimes has been applied due to the difficulty of experimental determining the velocity fields and problematic analyzing the system of hydrodynamic differential Navier-Stokes equations with variable proportionality ratios.

A Cartesian Explicit Solver for Complex Hydrodynamic Applications

2014 ◽  
Author(s):  
P. Bigay ◽  
A. Bardin ◽  
G. Oger ◽  
D. Le Touzé
Keyword(s):  
Level Set ◽  
Incompressible Flows ◽  
Stokes Equations ◽  
Simulation Method ◽  
Navier Stokes ◽  
Viscous Effects ◽  
Navier Stokes Equations ◽  
Eddy Simulation ◽  
Flow Past A Cylinder ◽  
Explicit Solver

In order to efficiently address complex problems in hydrodynamics, the advances in the development of a new method are presented here. This method aims at finding a good compromise between computational efficiency, accuracy, and easy handling of complex geometries. The chosen method is an Explicit Cartesian Finite Volume method for Hydrodynamics (ECFVH) based on a compressible (hyperbolic) solver, with a ghost-cell method for geometry handling and a Level-set method for the treatment of biphase-flows. The explicit nature of the solver is obtained through a weakly-compressible approach chosen to simulate nearly-incompressible flows. The explicit cell-centered resolution allows for an efficient solving of very large simulations together with a straightforward handling of multi-physics. A characteristic flux method for solving the hyperbolic part of the Navier-Stokes equations is used. The treatment of arbitrary geometries is addressed in the hyperbolic and viscous framework. Viscous effects are computed via a finite difference computation of viscous fluxes and turbulent effects are addressed via a Large-Eddy Simulation method (LES). The Level-Set solver used to handle biphase flows is also presented. The solver is validated on 2-D test cases (flow past a cylinder, 2-D dam break) and future improvements are discussed.

Sign in / Sign up

Export Citation Format

Share Document