A Fully Eulerian Approach to Particle-Laden Compressible Flows

2000 ◽  
Author(s):  
Ali Dolatabadi ◽  
Javad Mostaghimi ◽  
Mihajlo Ivanovic
Keyword(s):  
Compressible Flows ◽  
Gas Flows ◽  
Governing Equations ◽  
Eulerian Approach ◽  
Expansion Waves ◽  
Hvof Thermal Spray ◽  
Flow Features ◽  
Energy Exchanges ◽  
Two Phases ◽  
Fully Eulerian Approach

Abstract Dense particles in highly compressible gas flows are analyzed using the Eulerian-Eulerian approach. Simulations are applied to a High Velocity Oxy-Fuel (HVOF) thermal spray torch. In this analysis, by using a fully Eulerian approach, the dispersed flow like the continuous flow is considered in the Eulerian frame whereby most of the physical aspects of the gas-particle flow in the HVOF process can be incorporated. These two phases are coupled through momentum and energy exchanges that are expressed in the form of source terms appearing in the governing equations. The numerical simulations show large variations in gas velocity and temperature both inside and outside the torch due to flow features such as mixing layers, shock waves, and expansion waves. The characteristics of the particles such as velocity and temperature are analyzed.

Numerical Investigation of a Fiber Web Effect on the Pressure Drop and Particles Collection in a Microchannel

2009 ◽  
Author(s):  
Alireza Dastan ◽  
Omid Abouali
Keyword(s):  
Pressure Drop ◽  
Flow Field ◽  
Numerical Investigation ◽  
Particle Motion ◽  
Particle Deposition ◽  
Hydraulic Diameter ◽  
Lagrangian Approach ◽  
Computational Domain ◽  
Governing Equations ◽  
Eulerian Approach

In this paper pressure drop and particle deposition in a microchannel with a hydraulic diameter of 225 micrometer is investigated numerically. Several hundred micron length fibers caught at the entrance of the channels making a “fiber web” also is modeled in this research. Governing equations for the flow field are solved with an Eulerian approach while the equations of particle motion in the flow are solved by a Lagrangian approach. Assuming the symmetry in the domain, one channel and the corresponding plenum are studied in the computational domain. For studying the effects of fibers in the flow, two fiber webs with four and six solid fibers are studied. The increase of pressure drop in the microchannel because of the entrance fiber web is computed and discussed. Also deposition and collection of the particles with various diameters at the fiber webs are also presented.

scholarly journals Decomposition of the temporal growth rate in linear instability of compressible gas flows

2015 ◽  
Vol 778 ◽  
pp. 120-132 ◽  
Author(s):  
Mario Weder ◽  
Michael Gloor ◽  
Leonhard Kleiser
Keyword(s):  
Growth Rate ◽  
Energy Balance ◽  
Linear Stability ◽  
Couette Flow ◽  
Stability Theory ◽  
Compressible Flows ◽  
Linear Instability ◽  
Linear Stability Theory ◽  
Gas Flows ◽  
Temporal Growth Rate

We present a decomposition of the temporal growth rate ${\it\omega}_{i}$ which characterises the evolution of wave-like disturbances in linear stability theory for compressible flows. The decomposition is based on the disturbance energy balance by Chu (Acta Mech., vol. 1 (3), 1965, pp. 215–234) and provides terms for production, dissipation and flux of energy as components of ${\it\omega}_{i}$. The inclusion of flux terms makes our formulation applicable to unconfined flows and flows with permeable or vibrating boundaries. The decomposition sheds light on the fundamental mechanisms determining temporal growth or decay of disturbances. The additional insights gained by the proposed approach are demonstrated by an investigation of two model flows, namely compressible Couette flow and a plane compressible jet.

scholarly journals Numerical solutions of ideal quantum gas dynamical flows governed by semiclassical ellipsoidal-statistical distribution

2014 ◽  
Vol 470 (2161) ◽  
pp. 20130413 ◽  
Author(s):  
Jaw-Yen Yang ◽  
Chih-Yuan Yan ◽  
Manuel Diaz ◽  
Juan-Chen Huang ◽  
Zhihui Li ◽  
...  
Keyword(s):  
Equilibrium Distribution ◽  
Numerical Solutions ◽  
Maximum Entropy Principle ◽  
Physical Space ◽  
Quantum Gas ◽  
Expansion Waves ◽  
Flow Features ◽  
Classical Gas ◽  
Entropy Principle ◽  
Ideal Quantum

The ideal quantum gas dynamics as manifested by the semiclassical ellipsoidal-statistical (ES) equilibrium distribution derived in Wu et al. (Wu et al . 2012 Proc. R. Soc. A 468 , 1799–1823 ( doi:10.1098/rspa.2011.0673 )) is numerically studied for particles of three statistics. This anisotropic ES equilibrium distribution was derived using the maximum entropy principle and conserves the mass, momentum and energy, but differs from the standard Fermi–Dirac or Bose–Einstein distribution. The present numerical method combines the discrete velocity (or momentum) ordinate method in momentum space and the high-resolution shock-capturing method in physical space. A decoding procedure to obtain the necessary parameters for determining the ES distribution is also devised. Computations of two-dimensional Riemann problems are presented, and various contours of the quantities unique to this ES model are illustrated. The main flow features, such as shock waves, expansion waves and slip lines and their complex nonlinear interactions, are depicted and found to be consistent with existing calculations for a classical gas.

Nonlinear Dynamics of Flexible L-Shaped Beam Based on Exact Modes Truncation

2017 ◽  
Vol 27 (03) ◽  
pp. 1750035 ◽  
Author(s):  
Tian-Jun Yu ◽  
Wei Zhang ◽  
Xiao-Dong Yang
Keyword(s):  
Nonlinear Dynamics ◽  
Linear Equations ◽  
Elliptic Functions ◽  
Governing Equations ◽  
Modal Interactions ◽  
Partial Differential ◽  
Shaped Beam ◽  
Higher Dimensional ◽  
Theoretical Predictions ◽  
Energy Exchanges

Nonlinear dynamics of flexible multibeam structures modeled as an L-shaped beam are investigated systematically considering the modal interactions. Taking into account nonlinear coupling and nonlinear inertia, Hamilton’s principle is employed to derive the partial differential governing equations of the structure. Exact mode functions are obtained by the coupled linear equations governing the horizontal and vertical beams and the results are verified by the finite element method. Then the exact modes are adopted to truncate the partial differential governing equations into two coupled nonlinear ordinary differential equations by using Galerkin method. The undamped free oscillations are studied in terms of Jacobi elliptic functions and results indicate that the energy exchanges are continual between the two modes. The saturation and jumping phenomena are then observed for the forced damped multibeam structure. Further, a higher-dimensional, Melnikov-type perturbation method is used to explore the physical mechanism leading to chaotic behaviors for such an autoparametric system. Numerical simulations are performed to validate the theoretical predictions.

An Object-Oriented CFD Code for Optimization of High Pressure Ratio Compressors

2012 ◽  
Author(s):  
Elmar Gröschel ◽  
Benjamin Rembold ◽  
Luca Mangani ◽  
Ernesto Casartelli
Keyword(s):  
Optimization Design ◽  
Compressible Flows ◽  
State Of The Art ◽  
Pressure Ratio ◽  
Flow Characteristics ◽  
Object Oriented ◽  
Special Treatment ◽  
3D Flow ◽  
High Pressure Ratio ◽  
Flow Features

The flow fields and performances of different transonic radial compressors of varying geometries and conceptual designs have been studied numerically. All the simulations were performed with a modified in-house 3D RANS solver based on an object-oriented open-source library. The solver uses an All-Mach algorithm with a special treatment for the pressure corrector equation to deal with highly compressible flows. The 3D flow field structures, the characteristics and integral quantities have been compared to the results of established, state-of-the-art commercial solvers as well as to measurements whenever possible. This paper demonstrates for various configurations that the main flow features and the flow characteristics have been captured by the new solver. Furthermore, the new solver is also capable of computing the delta variations of similar designs. This is an essential step for the broad application of the new solver for optimization design cycles.

scholarly journals Two-Phase Flow in Capillary Tubes

1964 ◽  
Vol 86 (3) ◽  
pp. 576-582 ◽  
Author(s):  
Mikio Suo ◽  
Peter Griffith
Keyword(s):  
Liquid Film ◽  
Two Phase Flow ◽  
Gas Flows ◽  
Bubble Flow ◽  
Phase Flow ◽  
Capillary Diameter ◽  
Two Phase ◽  
Adiabatic Flow ◽  
Horizontal Tubes ◽  
Two Phases

The adiabatic flow of two phases, gas and liquid, has been studied in horizontal tubes of capillary diameter. The flow has been studied primarily in the regime where the gas flows as long bubbles separated from the wall of the tube by a liquid film and from each other by slugs of liquid. In this regime the density and the thickness of the liquid film around a bubble have been correlated. The conditions under which the long bubble flow can exist and under which the correlations are valid have been determined.

scholarly journals A fully Eulerian approach to particle inertial deposition in a physiologically realistic bifurcation

2013 ◽  
Vol 37 (8) ◽  
pp. 5591-5605 ◽  
Author(s):  
M. Pilou ◽  
V. Antonopoulos ◽  
E. Makris ◽  
P. Neofytou ◽  
S. Tsangaris ◽  
...  
Keyword(s):  
Eulerian Approach ◽  
Fully Eulerian Approach

A slip with entrained liquid fraction approach to compressible two-phase flow in nozzles

1999 ◽  
Vol 213 (7) ◽  
pp. 729-740 ◽  
Author(s):  
D A McNeil
Keyword(s):  
Compressible Flows ◽  
Critical Pressure ◽  
Liquid Fraction ◽  
Critical Mass ◽  
Gas Flows ◽  
Two Phase ◽  
Pressure Drops ◽  
Supply Pipe ◽  
Energy Equations ◽  
Liquid Flows

Ideal flow theory adequately predicts pressure drops, critical mass flowrates and critical pressure ratios for single-phase gas flows in nozzles. A model based on these principles has been developed for two-phase, gas-liquid flows using a slip with entrained liquid fraction approach. The method relies on being able to establish the momentum flux of the fluid in the upstream supply pipe and therefore allows pipe flow correlations for slip ratios and entrained liquid fractions to be used at the nozzle inlet. Choking conditions are established from an isentropic pressure pulse approach. This produces a speed of sound for the two-phase mixture that gives choking conditions that are compatible with the end-limits of the momentum and energy equations used to estimate the pressure drops for non-choked compressible flows. This allows a consistency in approach between non-choked compressible and choked flows. The model predictions of pressure drops, critical pressure ratios and critical mass flowrates compare well with data sources and are an improvement on those made by other models available in the open literature.

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