scholarly journals CURRENT - A Computer Code for Modeling Two-Dimensional, Chemically Reaccting, Low Mach Number Flows

1996 ◽  
Author(s):  
W.S. Winters ◽  
G.H. Evans ◽  
C.D. Moen
Keyword(s):  
Mach Number ◽  
Computer Code ◽  
Two Dimensional ◽  
Low Mach Number

Inverse cascades in two‐dimensional compressible turbulence. I. Incompressible forcing at low Mach number

1990 ◽  
Vol 2 (8) ◽  
pp. 1481-1486 ◽  
Author(s):  
J. P. Dahlburg ◽  
R. B. Dahlburg ◽  
J. H. Gardner ◽  
J. M. Picone
Keyword(s):  
Mach Number ◽  
Compressible Turbulence ◽  
Two Dimensional ◽  
Low Mach Number

Incompressible limit for the two-dimensional isentropic Euler system with critical initial data

2014 ◽  
Vol 144 (6) ◽  
pp. 1127-1154 ◽  
Author(s):  
Taoufik Hmidi ◽  
Samira Sulaiman
Keyword(s):  
Mach Number ◽  
Initial Data ◽  
Euler System ◽  
Incompressible Limit ◽  
Two Dimensional ◽  
Low Mach Number ◽  
Low Mach Number Limit ◽  
Critical Besov Space ◽  
Convergence Results ◽  
Incompressible Euler

We study the low-Mach-number limit for the two-dimensional isentropic Euler system with ill-prepared initial data belonging to the critical Besov space . By combining Strichartz estimates with the special structure of the vorticity, we prove that the lifespan of the solutions goes to infinity as the Mach number goes to zero. We also prove strong convergence results of the incompressible parts to the solution of the incompressible Euler system.

Acoustic destablilization of vortices

1979 ◽  
Vol 290 (1372) ◽  
pp. 353-371 ◽  
Keyword(s):  
Boundary Condition ◽  
Growth Rate ◽  
Mach Number ◽  
Acoustic Waves ◽  
Polar Angle ◽  
Inviscid Flow ◽  
Two Dimensional ◽  
Low Mach Number ◽  
The Stability ◽  
Good Agreement

A line vortex which has uniform vorticity 2Ω 0 in its core is subjected to a small two-dimensional disturbance whose dependence on polar angle is e imθ . The stability is examined according to the equations of compressible, inviscid flow in a homentropic medium. The boundary condition at infinity is that of outgoing acoustic waves, and it is found that this capacity to radiate leads to a slow instability by comparison with the corresponding incompressible vortex which is stable. Numerical eigenvalues are computed as functions of the mode number m and the Mach number M based on the circumferential speed of the vortex. These are compared with an asymptotic analysis for the m = 2 mode at low Mach number in which it is found that the growth rate is (π/ 32) M 4 Ω 0 in good agreement with the numerical results.

Radiation from vortex filament motion near a half plane

1972 ◽  
Vol 51 (2) ◽  
pp. 357-362 ◽  
Author(s):  
D. G. Crighton
Keyword(s):  
Mach Number ◽  
Singular Perturbation ◽  
Half Plane ◽  
Perturbation Methods ◽  
Sound Field ◽  
Vortical Flow ◽  
Two Dimensional ◽  
Low Mach Number ◽  
Radiated Energy ◽  
Singular Perturbation Methods

The two-dimensional low Mach number sound field from the passage of a line vortex around the edge of a rigid half plane is calculated by singular perturbation methods. Simple exact expressions are given for the space-time variation of the acoustic field, and for the total radiated energy and its frequency spectrum. These expressions show in particular that the effect of the half plane is to increase the energy radiated by a nearby vortical flow by M−3, where M is a characteristic Mach number.

Reduced-Order Modeling of Low Mach Number Unsteady Microchannel Flows

2014 ◽  
Vol 136 (5) ◽  
Author(s):  
Leila Issa ◽  
Issam Lakkis
Keyword(s):  
Mach Number ◽  
Boundary Conditions ◽  
Stokes Equations ◽  
Solid Boundary ◽  
Two Dimensional ◽  
Slip Boundary Conditions ◽  
Reduced Order ◽  
Low Mach Number ◽  
First Order ◽  
Slip Boundary

We present reduced-order models of unsteady low-Mach-number ideal gas flows in two-dimensional rectangular microchannels subject to first-order slip-boundary conditions. The pressure and density are related by a polytropic process, allowing for isothermal or isentropic flow assumptions. The Navier–Stokes equations are simplified using low-Mach-number expansions of the pressure and velocity fields. Up to first order, this approximation results in a system that is subject to no-slip condition at the solid boundary. The second-order system satisfies the slip-boundary conditions. The resulting equations and the subsequent pressure-flow-rate relationships enable modeling the flow using analog circuit components. The accuracy of the proposed models is investigated for steady and unsteady flows in a two-dimensional channel for different values of Mach and Knudsen numbers.

Artificial Compressibility Method and Preconditioning Method for Solving Two Dimensional Incompressibile Flow

2011 ◽  
Author(s):  
Hyungro Lee ◽  
Einkeun Kwak ◽  
Seungsoo Lee
Keyword(s):  
Mach Number ◽  
Turbulent Flows ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Two Dimensional ◽  
Navier Stokes Equations ◽  
Low Mach Number ◽  
Artificial Compressibility ◽  
Artificial Compressibility Method ◽  
Preconditioning Method

In this study, two commonly used numerical methods for the analysis of incompressible flows (or low Mach number flows), Chorins’ artificial compressibility method and Wiess and Smith’s preconditioning method are compared. Also, the convergence characteristics of two methods are numerically investigated for two-dimensional laminar and turbulent flows. Although the two methods have similar governing equations, the eigensystems and other details are very different. The eigensystems of the artificial compressibility method and the preconditioning method are analytically examined. An artificial compressibility code that solves the incompressible RANS (Reynolds Averaged Navier-Stokes) equations is newly developed for the study. An artificial compressibility code and a well-verified existing low Mach number code uses Roe’s approximate Riemann solver in conjunction with a cell centered finite volume method. Using MUSCL extrapolation with nonlinear limiters, 2nd order spatial accuracy is achieved while maintaining TVD (total variation diminishing) property. AF-ADI (approximate factorization-alternate direction implicit) method is used to get the steady solution for both codes. Menter’s k–ω SST turbulence model is used for the analysis of turbulent flows. Navier-Stokes equations and the turbulence model equations are solved in a loosely coupled manner.

Reduced Order Models of Low Mach Number Isothermal Flows in Microchannels

2013 ◽  
Author(s):  
Leila Issa ◽  
Issam Lakkis
Keyword(s):  
Mach Number ◽  
Analog Circuit ◽  
Stokes Equations ◽  
Momentum Equation ◽  
Ideal Gas ◽  
Reduced Order Models ◽  
Two Dimensional ◽  
Reduced Order ◽  
Low Mach Number ◽  
Circuit Components

We present reduced order models of unsteady low Mach number isothermal ideal gas flows in two-dimensional rectangular microchannels subject to first order slip boundary conditions. The Navier-Stokes equations are simplified using Low Mach Number expansions of the pressure and velocity fields. This approximation allows decoupling the density from spatial pressure variations, thus simplifying the momentum equation. The resulting diffusion equation and the subsequent pressure-flow-rate relationship enables modeling the flow using analog circuit components. The accuracy of the proposed models is investigated for steady and unsteady flows in a two-dimensional channel for different values of Reynolds and Knudsen numbers.

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