Using simulations of solar surface convection as boundary conditions on global simulations

AbstractDirect numerical simulations of convective stellar envelopes, are divided between two different physical regimes, that are rather difficult to reconcile — at least with the computational power of present-day computers. This paper outlines an attempt at bridging the gap between surface and interior simulations of convection.

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Implementation of Lees–Edwards periodic boundary conditions for direct numerical simulations of particle dispersions under shear flow

The Journal of Chemical Physics ◽

10.1063/1.3537974 ◽

2011 ◽

Vol 134 (6) ◽

pp. 064110 ◽

Cited By ~ 18

Author(s):

Hideki Kobayashi ◽

Ryoichi Yamamoto

Keyword(s):

Shear Flow ◽

Boundary Conditions ◽

Numerical Simulations ◽

Periodic Boundary ◽

Periodic Boundary Conditions ◽

Direct Numerical Simulations

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Shear Driven Turbulence and Coherent Structures in Solar Surface Simulations

Proceedings of the International Astronomical Union ◽

10.1017/s174392130802348x ◽

2008 ◽

Vol 4 (S252) ◽

pp. 451-461 ◽

Cited By ~ 1

Author(s):

F. Kupka

Keyword(s):

High Resolution ◽

Boundary Conditions ◽

Numerical Simulations ◽

Observational Data ◽

Coherent Structures ◽

Solar Surface ◽

Large Set ◽

Mode Excitation

AbstractNumerical simulations of convection near the solar surface are now advanced enough to reproduce both a large set of observational data and provide tests for convection models. We discuss the role of coherent structures in models of solar p-mode excitation, for which the analysis of numerical simulations has provided key inputs in the modelling. The robustness of these simulations is shown by a comparison illustrating the influence of boundary conditions on ensemble averaged quantities. In a concluding example advanced high resolution simulations are shown to resolve the onset of shear driven turbulence generated by up- and downflow structures.

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Boundary conditions for direct numerical simulations of free jets

10.2514/6.1999-287 ◽

1999 ◽

Author(s):

Gregory Hernandez ◽

Gunther Brenner

Keyword(s):

Boundary Conditions ◽

Numerical Simulations ◽

Direct Numerical Simulations ◽

Free Jets

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A dynamic multi-scale approach for turbulent inflow boundary conditions in spatially developing flows

Journal of Fluid Mechanics ◽

10.1017/s0022112010005616 ◽

2011 ◽

Vol 670 ◽

pp. 581-605 ◽

Cited By ~ 47

Author(s):

GUILLERMO ARAYA ◽

LUCIANO CASTILLO ◽

CHARLES MENEVEAU ◽

KENNETH JANSEN

Keyword(s):

Boundary Layer ◽

Boundary Conditions ◽

Pressure Gradient ◽

Numerical Simulations ◽

Dynamic Method ◽

Adverse Pressure Gradient ◽

Direct Numerical Simulations ◽

Gradient Flows ◽

Multi Scale ◽

Turbulence Transition

A dynamic method for prescribing realistic inflow boundary conditions is presented for simulations of spatially developing turbulent boundary layers. The approach is based on the rescaling–recycling method proposed by Lund, Wu & Squires (J. Comput. Phys, vol. 140, 1998, pp. 233–258) and the multi-scale method developed by Araya, Jansen & Castillo (J. Turbul., vol. 10, no. 36, 2009, pp. 1–33). The rescaling process requires prior knowledge about how the velocity and length scales are related between the inlet and recycle stations. Here a dynamic approach is proposed in which such information is deduced dynamically by involving an additional plane, the so-called test plane located between the inlet and recycle stations. The approach distinguishes between the inner and outer regions of the boundary layer and enables the use of multiple velocity scales. This flexibility allows applications to boundary layer flows with pressure gradients and avoids the need to prescribe empirically the friction velocity and other flow parameters at the inlet of the domain. The dynamic method is tested in direct numerical simulations of zero, favourable and adverse pressure gradient flows. The dynamically obtained scaling exponents for the downstream evolution of boundary layer parameters are found to fluctuate in time, but on average they agree with the expected values for zero, favourable and adverse pressure gradient flows. Comparisons of the results with data from experiments, and from other direct numerical simulations that use much longer computational domains to capture laminar-to-turbulence transition, demonstrate the suitability of the proposed dynamic method.

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