A 3-D chimera grid embedding technique

Benek, John A.; Buning, Pieter G.; Steger, J. L.

doi:10.2514/6.1985-1523

Cited by 478 publications

(196 citation statements)

References 5 publications

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“…Instead, the overset grid approach used by Burton & Eaton (2005) is adopted and extended to multiple particles: around each particle, a body-fitted (spherical) staggered non-uniform mesh is used, overset on a staggered Cartesian mesh. A finite difference technique that uses multiple overset curvilinear meshes has also been called a composite mesh difference technique (Starius 1977), a chimera grid-embedding technique (Benek, Buning & Steger 1985) and a composite overlapping grid technique (Chesshire & Henshaw 1990;Henshaw 1994). With the overset technique, not only can the number of grid points be limited, but also its body-fitted property facilitates a straightforward computation of the turbulent dissipation rate on the particle surfaces.…”

Section: Introductionmentioning

confidence: 99%

Particle-resolved direct numerical simulation of homogeneous isotropic turbulence modified by small fixed spheres

Vreman

2016

J. Fluid Mech.

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A statistically stationary homogeneous isotropic turbulent flow modified by 64 small fixed non-Stokesian spherical particles is considered. The particle diameter is approximately twice the Kolmogorov length scale, while the particle volume fraction is 0.001. The Taylor Reynolds number of the corresponding unladen flow is 32. The particle-laden flow has been obtained by a direct numerical simulation based on a discretization of the incompressible Navier-Stokes equations on 64 spherical grids overset on a Cartesian grid. The global (space-and time-averaged) turbulence kinetic energy is attenuated by approximately 9 %, which is less than expected. The turbulence dissipation rate on the surfaces of the particles is enhanced by two orders of magnitude. More than 5 % of the total dissipation occurs in only 0.1 % of the flow domain. The budget of the turbulence kinetic energy has been computed, as a function of the distance to the nearest particle centre. The budget illustrates how energy relatively far away from particles is transported towards the surfaces of the particles, where it is dissipated by the (locally enhanced) turbulence dissipation rate. The energy flux towards the particles is dominated by turbulent transport relatively far away from particles, by viscous diffusion very close to the particles, and by pressure diffusion in a significant region in between. The skewness and flatness factors of the pressure, velocity and velocity gradient have also been computed. The global flatness factor of the longitudinal velocity gradient, which characterizes the intermittency of small scales, is enhanced by a factor of six. In addition, several point-particle simulations based on the Schiller-Naumann drag correlation have been performed. A posteriori tests of the point-particle simulations, comparisons in which the particle-resolved results are regarded as the standard, show that, in this case, the point-particle model captures both the turbulence attenuation and the fraction of the turbulence dissipation rate due to particles reasonably well, provided the (arbitrary) size of the fluid volume over which each particle force is distributed is suitably chosen.

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Section: Introductionmentioning

confidence: 99%

Particle-resolved direct numerical simulation of homogeneous isotropic turbulence modified by small fixed spheres

Vreman

2016

J. Fluid Mech.

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“…For the modelling of the turbulence, the Menter SST turbulence model is used and the simulations are performed fully turbulent. All components of the setup are meshed separately with a fully resolved boundary layer (y + ≈ 1) and overlapped, using the CHIMERA technique (Benek et al, 1986). The process chain, as used for the present investigations, was developed at the IAG (Meister, 2015).…”

mentioning

confidence: 99%

About the suitability of different numerical methods to reproduce model wind turbine measurements in a wind tunnel with high blockage ratio

Klein¹,

Bartholomay²,

Marten³

et al. 2017

Preprint

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Abstract. Numerical and experimental investigations of a model wind turbine with a diameter of 3.0m are described in the present paper. The objectives of the study are the provision of validation data, the comparison and evaluation of methods of different fidelity and the assessment of the influence of the wind tunnel walls by comparison of measurements to simulations with and without wind tunnel walls. The experiments were carried out in the large wind tunnel of the TU Berlin. With the Lifting Line Free Vortex Wake (LLFVW) code QBlade, the turbine was simulated under far field conditions at the TU Berlin. 5URANS simulations were performed at the University of Stuttgart with the CFD code FLOWer for far field condition to draw a comparison to QBlade. Moreover, CFD simulations of the turbine in a wind tunnel were carried out, as the walls have a significant influence on the turbine performance.Comparisons between experiment, the LLFVW code and CFD include on-blade velocities, angle of attack and bending moments. Comparisons of flow fields are drawn between experiment and the CFD code. 10A good accordance was achieved for the flow fields, the on-blade velocity and the angle of attack, whereas deviations occur for the bending moments.

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“…3. The trilinear interpolation algorithm yields interpolation coefficients for a point either inside or outside the element (the latter case is actually and extrapolation).…”

Section: Stencil-jumpingmentioning

confidence: 99%

PEGSUS 3.0 User's Manual

Dietz¹,

Suhs²

1989

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A 3-D chimera grid embedding technique

Cited by 478 publications

References 5 publications

Particle-resolved direct numerical simulation of homogeneous isotropic turbulence modified by small fixed spheres

Particle-resolved direct numerical simulation of homogeneous isotropic turbulence modified by small fixed spheres

About the suitability of different numerical methods to reproduce model wind turbine measurements in a wind tunnel with high blockage ratio

PEGSUS 3.0 User's Manual

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