Floquet instability of a large density ratio liquid-gas coaxial jet with periodic fluctuation

AbstractWe present a three dimensional preconditioned implicit free-surface capture scheme on tetrahedral grids. The current scheme improves our recently reported method [10] in several aspects. Specifically, we modified the original eigensystem by applying a preconditioning matrix so that the new eigensystem is virtually independent of density ratio, which is typically large for practical two-phase problems. Further, we replaced the explicit multi-stage Runge-Kutta method by a fully implicit Euler integration scheme for the Navier-Stokes (NS) solver and the Volume of Fluids (VOF) equation is now solved with a second order Crank-Nicolson implicit scheme to reduce the numerical diffusion effect. The preconditioned restarted Generalized Minimal RESidual method (GMRES) is then employed to solve the resulting linear system. The validation studies show that with these modifications, the method has improved stability and accuracy when dealing with large density ratio two-phase problems.

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Numerical Simulation of Rayleigh-Taylor Instability with Large Density Ratios Based on RKDG Method

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.423-426.1751 ◽

2013 ◽

Vol 423-426 ◽

pp. 1751-1756 ◽

Cited By ~ 1

Author(s):

Jun Wu Tian ◽

Xiang Jiang Yuan

Keyword(s):

Body Force ◽

Contact Discontinuity ◽

Density Ratio ◽

Taylor Instability ◽

Interface Capturing ◽

Instability Problem ◽

Large Density ◽

Large Density Ratio ◽

Rayleigh Taylor Instability ◽

Density Ratios

Rayleigh-Taylor instability problem with large density ratios is simulated by RKDG method which is developed for Euler equations with an additional body force corresponding to the gravity. The interface capturing ability of RKDG method is testified, while the density ratio (heavy to light) ranges from 3 to 20. Numerical results show that RKDG method has capability to pursue contact discontinuity in Rayleigh-Taylor instability with large density ratio. In the late stage of Rayleigh-Taylor instability problem, the contact line begins to crash, but the numerical solution is still smooth near the interface and has high resolution.

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LBM Application in Two-Phase Fluid Flow with Large Density Ratio

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.476-478.871 ◽

2012 ◽

Vol 476-478 ◽

pp. 871-875

Author(s):

Qing Ming Chang ◽

Yin Kai Yang ◽

Jing Yuan ◽

Xia Chen ◽

Min Zhang

Keyword(s):

Gravity Wave ◽

Numerical Solutions ◽

Density Ratio ◽

Surface Tension Force ◽

Analytic Solutions ◽

Lattice Boltzmann Model ◽

Two Phase ◽

Large Density ◽

Large Density Ratio ◽

Parasitic Currents

In this paper, a stable lattice Boltzmann model (LBM) based on non-ideal gases is presented for simulation of incompressible two-phase flows with large density ratio. To reduce the parasitic currents across the interface and correspondingly increase the numerical stability, the stress and potential forms of the surface tension force is employed. The applications to a stationary bubble and capillary-gravity wave with density ratio 1000 are given to verify this model. The numerical solutions is agree well with analytic solutions of the Laplace's law and capillary-gravity wave.

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Effects of Coolant Density Ratio on Film Cooling Performance on a Vane

Volume 5: Turbo Expo 2003, Parts A and B ◽

10.1115/gt2003-38582 ◽

2003 ◽

Cited By ~ 11

Author(s):

J. Michael Cutbirth ◽

David G. Bogard

Keyword(s):

Film Cooling ◽

Density Ratio ◽

Operating Conditions ◽

Cooling Performance ◽

Large Density ◽

Performance Trends ◽

Large Density Ratio ◽

Small Density ◽

Adiabatic Effectiveness ◽

Density Ratios

Film cooling performance was studied on a simulated turbine vane model with an objective of determining how much the coolant density ratio affects this performance. Experiments were conducted using coolant density ratios of 1.8 and 1.2. The purpose of the study was to determine if tests done at small density ratios (which is often more viable in a laboratory) can give reasonable predictions of performance at more realistic large density ratios. Furthermore, appropriate scaling parameters were determined. The mainstream flow was operated with low and high turbulence levels. Adiabatic effectiveness was measured in the showerhead region of the vane, and following the first row of coolant holes on the pressure side. Adiabatic effectiveness performance using small density ratio coolant gave performance trends similar to the large density ratio coolant, but quantitative values differed by varying amount depending on operating conditions.

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