scholarly journals On baer-nunziato multiphase flow models

2019 ◽  
Vol 66 ◽  
pp. 61-83
Author(s):  
M. Hillairet
Keyword(s):  
Multiphase Flow ◽  
Stokes Equations ◽  
Analytical Tool ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Models ◽  
Flow Systems

In these notes, we present an analytical tool for the derivation of Baer-Nunziato multiphase flow systems with one velocity. We explain the method in the case of the isentropic Navier Stokes equations. We then apply this method to models with temperature and show the main computations which are necessary to the derivation.

Rotordynamic Coefficients of Labseals for Turbines: Comparing CFD Results With Experimental Data on a Comb-Grooved Labyrinth

2005 ◽  
Author(s):  
Joachim Schettel ◽  
Martin Deckner ◽  
Klaus Kwanka ◽  
Bernd Lu¨neburg ◽  
Rainer Nordmann
Keyword(s):  
Stokes Equations ◽  
Labyrinth Seal ◽  
Navier Stokes ◽  
Test Rig ◽  
Navier Stokes Equations ◽  
Detailed Model ◽  
Identification Methods ◽  
Rotating Speed ◽  
Flow Models ◽  
Rotordynamic Coefficients

The main goal of this paper is to improve identification methods for rotordynamic coefficients of labseals for turbines. This aim was achieved in joint effort of the Technische Universita¨t Mu¨nchen, working on experimental identification methods for rotordynamic coefficients, the University of Technology, Darmstadt, working on prediction methods, and Siemens AG, realizing the results. The paper focuses on a short comb-grooved labyrinth seal. Short labseals, amongst others the above mentioned comb-grooved labyrinth, were examined. by means of a very accurately measuring test rig. The rotor was brought into statically eccentric positions relative to the stator, in order to measure the circumferential pressure distribution as a function of pressure, rotating speed and entrance swirl. The data collected were used to validate results obtained with a numerical method. The theoretical approach is based on a commercial CFD tool, which solves the Navier Stokes equations using numerical methods. As a result, a detailed model of the flow within the test rig is produced. The efforts of computation here are greater than when compared with the likewise wide-spread Bulk flow models, however improved accuracy and flexibility is expected. As the validation of the model is successful, it could then be used to gain further insight in the flow within the seal, and to understand the results better. This showed that rotordynamic coefficients of labseals gained from different test rigs are not necessarily comparable.

An unsteady two-cell vortex solution of the Navier—Stokes equations

1970 ◽  
Vol 41 (3) ◽  
pp. 673-687 ◽  
Author(s):  
P. G. Bellamy-Knights
Keyword(s):  
Radial Flow ◽  
Stokes Equations ◽  
Circumferential Velocity ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Radial Flux ◽  
Vortex Solution ◽  
Flow Systems ◽  
Vortex Solutions

The steady two-cell viscous vortex solution of Sullivan (1959) is extended to yield unsteady two-cell viscous vortex solutions which behave asymptotically as certain analogous unsteady one-cell solutions of Rott (1958). The radial flux is a parameter of the solution, and the effect of the radial flow on the circumferential velocity, is analyzed. The work suggests an explanation for the eventual dissipation of meteorological flow systems such as tornadoes.

Multiphase Flow Simulation of Water-Entry and -Exit of Axisymmetric Bodies

2013 ◽  
Author(s):  
Van-Tu Nguyen ◽  
Cong-Tu Ha ◽  
Warn-Gyu Park
Keyword(s):  
Multiphase Flow ◽  
Stokes Equations ◽  
Flow Simulation ◽  
Water Entry ◽  
Navier Stokes ◽  
Water Impact ◽  
Navier Stokes Equations ◽  
Vertical Accelerations ◽  
Underwater Projectile ◽  
Water Exit

A fully-compressible, multiphase, homogeneous mixture model, based on unsteady Reynolds-averaged Navier-Stokes equations is presented in this study. Dual-time preconditioning method was employed to improve the computational efficiency of the solution. The multiphase flow solver has been applied to computations of: (1) cavitating flows over underwater projectiles; (2) transonic flow past an underwater projectile; (3) water impact of a circular cylinder entering the water; (4) water-entry of a hemisphere with one degree of freedom; and (5) supercavitating flows over an axisymmetric projectile during water-entry and water-exit. The surface pressure coefficients, water impact forces, vertical accelerations, and impact velocities are compared with available experiments and other published results. Good agreements with those results are obtained. Aspects of water-entry and water-exit flow physics of a projectile with and without gaseous exhaust plume including cavity shape, phase topography and drag coefficients are presented.

A Coupled Approach for Fluid Dynamic Problems Using the PDE Framework Peano

2012 ◽  
Vol 12 (1) ◽  
pp. 65-84 ◽  
Author(s):  
Philipp Neumann ◽  
Hans-Joachim Bungartz ◽  
Miriam Mehl ◽  
Tobias Neckel ◽  
Tobias Weinzierl
Keyword(s):  
Lattice Boltzmann ◽  
Stokes Equations ◽  
Fluid Dynamic ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Models ◽  
Lattice Boltzmann Simulations ◽  
Improved Stability ◽  
Coupling Strategy ◽  
Pde Framework

AbstractWe couple different flow models, i.e. a finite element solver for the Navier-Stokes equations and a Lattice Boltzmann automaton, using the framework Peano as a common base. The new coupling strategy between the meso- and macroscopic solver is presented and validated in a 2D channel flow scenario. The results are in good agreement with theory and results obtained in similar works by Latt et al. In addition, the test scenarios show an improved stability of the coupled method compared to pure Lattice Boltzmann simulations.

scholarly journals An exact solution of the Navier-Stokes equations for swirl flow models through porous pipes

2006 ◽  
Author(s):  
N. Vlachakis ◽  
A. Fatsis ◽  
A. Panoutsopoulou ◽  
E. Kioussis ◽  
M. Kouskouti ◽  
...  
Keyword(s):  
Exact Solution ◽  
Stokes Equations ◽  
Swirl Flow ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Flow Models

scholarly journals Well-posedness analysis of multicomponent incompressible flow models

2021 ◽  
Author(s):  
Dieter Bothe ◽  
Pierre-Etienne Druet
Keyword(s):  
Stokes Equations ◽  
Strong Solutions ◽  
Navier Stokes ◽  
Well Posedness ◽  
Navier Stokes Equations ◽  
Flow Models ◽  
Change Of Variables ◽  
Algebraic Formula ◽  
Time Existence ◽  
Specific Volumes

AbstractIn this paper, we extend our study of mass transport in multicomponent isothermal fluids to the incompressible case. For a mixture, incompressibility is defined as the independence of average volume on pressure, and a weighted sum of the partial mass densities stays constant. In this type of models, the velocity field in the Navier–Stokes equations is not solenoidal and, due to different specific volumes of the species, the pressure remains connected to the densities by algebraic formula. By means of a change of variables in the transport problem, we equivalently reformulate the PDE system as to eliminate positivity and incompressibility constraints affecting the density, and prove two type of results: the local-in-time well-posedness in classes of strong solutions, and the global-in-time existence of solutions for initial data sufficiently close to a smooth equilibrium solution.

scholarly journals A Comparison of Simplified Two-dimensional Flow Models Exemplified by Water Flow in a Cavern

2017 ◽  
Vol 64 (3-4) ◽  
pp. 141-154
Author(s):  
Dzmitry Prybytak ◽  
Piotr Zima
Keyword(s):  
Water Flow ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
Flow Models ◽  
Two Dimensional Flow ◽  
Flow Through ◽  
Potential Flow Model

AbstractThe paper shows the results of a comparison of simplified models describing a two-dimensional water flow in the example of a water flow through a straight channel sector with a cavern. The following models were tested: the two-dimensional potential flow model, the Stokes model and the Navier-Stokes model. In order to solve the first two, the boundary element method was employed, whereas to solve the Navier-Stokes equations, the open-source code library OpenFOAM was applied. The results of numerical solutions were compared with the results of measurements carried out on a test stand in a hydraulic laboratory. The measurements were taken with an ADV probe (Acoustic Doppler Velocimeter). Finally, differences between the results obtained from the mathematical models and the results of laboratory measurements were analysed.

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