A new fractional time-stepping method for variable density incompressible flows

2013 ◽  
Vol 242 ◽  
pp. 124-137 ◽  
Author(s):  
Ying Li ◽  
Liquan Mei ◽  
Jiatai Ge ◽  
Feng Shi
Keyword(s):  
Incompressible Flows ◽  
Variable Density ◽  
Time Stepping

Application of Preconditioning Method to Gas-Liquid Two-Phase Flow Computations

2003 ◽  
Author(s):  
Byeong Rog Shin ◽  
Satoru Yamamoto ◽  
Xin Yuan
Keyword(s):  
Numerical Method ◽  
Incompressible Flows ◽  
Two Phase Flow ◽  
Tvd Scheme ◽  
Phase Flow ◽  
Internal Flows ◽  
Two Phase ◽  
Time Stepping ◽  
Dual Time Stepping ◽  
Preconditioning Method

A preconditioned numerical method for gas-liquid two-phase flows is applied to solve cavitating flow. The present method employs a finite-difference method of dual time-stepping integration procedure and Roe’s flux difference splitting approximation with MUSCL-TVD scheme. A homogeneous equilibrium cavitation model is used. The present density based numerical method permits simple treatment of the whole gas-liquid two-phase flow field including wave propagation, large density changes and incompressible flows characteristics at low Mach number. By this method, two-dimensional internal flows through a backward-facing step duct, a venturi tube and decelerating cascades are computed. Comparisons of predicted results with experiments are provided and discussed.

scholarly journals A numerical study of a variable-density low-speed turbulent mixing layer

2017 ◽  
Vol 830 ◽  
pp. 569-601 ◽  
Author(s):  
Antonio Almagro ◽  
Manuel García-Villalba ◽  
Oscar Flores
Keyword(s):  
Growth Rate ◽  
Mach Number ◽  
Incompressible Flows ◽  
Numerical Study ◽  
Density Ratio ◽  
Mixing Layer ◽  
Variable Density ◽  
The Self ◽  
Low Speed ◽  
Self Similar

Direct numerical simulations of a temporally developing, low-speed, variable-density, turbulent, plane mixing layer are performed. The Navier–Stokes equations in the low-Mach-number approximation are solved using a novel algorithm based on an extended version of the velocity–vorticity formulation used by Kim et al. (J. Fluid Mech., vol 177, 1987, 133–166) for incompressible flows. Four cases with density ratios $s=1,2,4$ and 8 are considered. The simulations are run with a Prandtl number of 0.7, and achieve a $Re_{\unicode[STIX]{x1D706}}$ up to 150 during the self-similar evolution of the mixing layer. It is found that the growth rate of the mixing layer decreases with increasing density ratio, in agreement with theoretical models of this phenomenon. Comparison with high-speed data shows that the reduction of the growth rates with increasing density ratio has a weak dependence with the Mach number. In addition, the shifting of the mixing layer to the low-density stream has been characterized by analysing one-point statistics within the self-similar interval. This shifting has been quantified, and related to the growth rate of the mixing layer under the assumption that the shape of the mean velocity and density profiles do not change with the density ratio. This leads to a predictive model for the reduction of the growth rate of the momentum thickness, which agrees reasonably well with the available data. Finally, the effect of the density ratio on the turbulent structure has been analysed using flow visualizations and spectra. It is found that with increasing density ratio the longest scales in the high-density side are gradually inhibited. A gradual reduction of the energy in small scales with increasing density ratio is also observed.

Multigrid Computation of Incompressible Flows Using Two-Equation Turbulence Models: Part II—Applications

1997 ◽  
Vol 119 (4) ◽  
pp. 900-905 ◽  
Author(s):  
X. Zheng ◽  
C. Liao ◽  
C. Liu ◽  
C. H. Sung ◽  
T. T. Huang
Keyword(s):  
Turbulent Flows ◽  
Incompressible Flows ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Time Stepping ◽  
Grid Algorithm ◽  
High Reynolds

In this paper, computational results are presented for three-dimensional high-Reynolds number turbulent flows over a simplified submarine model. The simulation is based on the solution of Reynolds-Averaged Navier-Stokes equations and two-equation turbulence models by using a preconditioned time-stepping approach. A multiblock method, in which the block loop is placed in the inner cycle of a multi-grid algorithm, is used to obtain versatility and efficiency. It was found that the calculated body drag, lift, side force coefficients and moments at various angles of attack or angles of drift are in excellent agreement with experimental data. Fast convergence has been achieved for all the cases with large angles of attack and with modest drift angles.

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