Nonreflecting Zonal Characteristic Boundary Condition for Direct Numerical Simulation of Aerodynamic Sound

AIAA Journal ◽  
2006 ◽  
Vol 44 (2) ◽  
pp. 402-405 ◽  
Author(s):  
Richard D. Sandberg ◽  
Neil D. Sandham
Keyword(s):  
Numerical Simulation ◽  
Boundary Condition ◽  
Direct Numerical Simulation ◽  
Aerodynamic Sound ◽  
Characteristic Boundary ◽  
Characteristic Boundary Condition

NUMERICAL SIMULATION OF FREE VORTEX WITH MODIFIED NAVIER–STOKES CHARACTERISTIC BOUNDARY CONDITIONS

2010 ◽  
Vol 24 (13) ◽  
pp. 1333-1336
Author(s):  
LIN CHEN ◽  
DENGBIN TANG ◽  
XIN GUO
Keyword(s):  
Boundary Condition ◽  
Compressible Flows ◽  
Diffusion Processes ◽  
Stokes Equations ◽  
Navier Stokes ◽  
Free Vortex ◽  
Navier Stokes Equations ◽  
Characteristic Boundary ◽  
Accurate Treatment ◽  
Characteristic Boundary Condition

The convection and diffusion processes of free vortex in compressible flows are simulated by using high precision numerical method to solve for the Navier–Stokes equations. Accurate treatment of the boundary condition is extremely important for simulation of vortex flows. The developed numerical methods are well presented by combining six-order non-dissipation compact schemes with Navier–Stokes characteristic boundary condition having transverse and viscous terms, and can accurately simulate the movement of free vortex. The numerical reflecting waves at the boundaries are well controlled.

scholarly journals Dissipation of shear-free turbulence near boundaries

2000 ◽  
Vol 422 ◽  
pp. 167-191 ◽  
Author(s):  
M. A. C. TEIXEIRA ◽  
S. E. BELCHER
Keyword(s):  
Numerical Simulation ◽  
Boundary Condition ◽  
Free Surface ◽  
Direct Numerical Simulation ◽  
Dissipation Rate ◽  
Solid Wall ◽  
Tangential Velocity ◽  
Main Role ◽  
Nonlinear Processes ◽  
Viscous Layer

The rapid-distortion model of Hunt & Graham (1978) for the initial distortion of turbulence by a flat boundary is extended to account fully for viscous processes. Two types of boundary are considered: a solid wall and a free surface. The model is shown to be formally valid provided two conditions are satisfied. The first condition is that time is short compared with the decorrelation time of the energy-containing eddies, so that nonlinear processes can be neglected. The second condition is that the viscous layer near the boundary, where tangential motions adjust to the boundary condition, is thin compared with the scales of the smallest eddies. The viscous layer can then be treated using thin-boundary-layer methods. Given these conditions, the distorted turbulence near the boundary is related to the undistorted turbulence, and thence profiles of turbulence dissipation rate near the two types of boundary are calculated and shown to agree extremely well with profiles obtained by Perot & Moin (1993) by direct numerical simulation. The dissipation rates are higher near a solid wall than in the bulk of the flow because the no-slip boundary condition leads to large velocity gradients across the viscous layer. In contrast, the weaker constraint of no stress at a free surface leads to the dissipation rate close to a free surface actually being smaller than in the bulk of the flow. This explains why tangential velocity fluctuations parallel to a free surface are so large. In addition we show that it is the adjustment of the large energy-containing eddies across the viscous layer that controls the dissipation rate, which explains why rapid-distortion theory can give quantitatively accurate values for the dissipation rate. We also find that the dissipation rate obtained from the model evaluated at the time when the model is expected to fail actually yields useful estimates of the dissipation obtained from the direct numerical simulation at times when the nonlinear processes are significant. We conclude that the main role of nonlinear processes is to arrest growth by linear processes of the viscous layer after about one large-eddy turnover time.

scholarly journals A Low Dissipative and Stable Cell-Centered Finite Volume Method with the Simultaneous Approximation Term for Compressible Turbulent Flows

Mathematics ◽  
2021 ◽  
Vol 9 (11) ◽  
pp. 1206
Author(s):  
Myeongseok Kang ◽  
Donghyun You
Keyword(s):  
Boundary Condition ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Simultaneous Approximation ◽  
Summation By Parts ◽  
Eddy Simulation ◽  
Characteristic Boundary ◽  
Simultaneous Approximation Term ◽  
Characteristic Boundary Condition ◽  
Volume Method

A simultaneous-approximation term is a non-reflecting boundary condition that is usually accompanied by summation-by-parts schemes for provable time stability. While a high-order convective flux based on reconstruction is often employed in a finite-volume method for compressible turbulent flow, finite-volume methods with the summation-by-parts property involve either equally weighted averaging or the second-order central flux for convective fluxes. In the present study, a cell-centered finite-volume method for compressible Naiver–Stokes equations was developed by combining a simultaneous-approximation term based on extrapolation and a low-dissipative discretization method without the summation-by-parts property. Direct numerical simulations and a large eddy simulation show that the resultant combination leads to comparable non-reflecting performance to that of the summation-by-parts scheme combined with the simultaneous-approximation term reported in the literature. Furthermore, a characteristic boundary condition was implemented for the present method, and its performance was compared with that of the simultaneous-approximation term for a direct numerical simulation and a large eddy simulation to show that the simultaneous-approximation term better maintained the average target pressure at the compressible flow outlet, which is useful for turbomachinery and aerodynamic applications, while the characteristic boundary condition better preserved the flow field near the outlet.

scholarly journals 0102 Direct numerical simulation of round jet using non periodic boundary condition

2010 ◽  
Vol 2010 (0) ◽  
pp. 9-10
Author(s):  
Koichi TSUJIMOTO ◽  
Hiroshi KATO ◽  
Koji AO ◽  
Toshihiko SHAKOUCHI ◽  
Toshitake ANDO
Keyword(s):  
Numerical Simulation ◽  
Boundary Condition ◽  
Direct Numerical Simulation ◽  
Periodic Boundary Condition ◽  
Periodic Boundary ◽  
Round Jet
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