Photo Chris Liverani
SCALABLE must “achieve the scaling to unprecedented performance, scalability, and energy efficiency of an industrial LBM-based computational fluid dynamics (CFD) software.” The following two benchmarks highlights the numerical precision with an academical convection of a vortex, and the turbulence modeling capacity with academical turbulent channels.
Both these benchmarks divided between a principal target, allowing a thorough validation of the property, and a secondary target, pushing the simulation to a more demanding situation.
The first test case is the CERFACS CO-VO, already performed on many codes.
An isentropic vortex is simply moving to the east of a periodic square grid. With time. The flow is supposed inviscid Euler Equations
|Convection speed||Uc = 170m/s (Mach 0.5)|
|Domain||-0.05, 0.05 m|
You can download a Cerfacs Technical report giving more details on the initialization equations here.
Vortex convected by LEOPARD, a LBM testbed from cerfacs, 10th turnaround.
In LBM, the streaming operator is aligned with the grid. Therefore a vortex convection from west to east is a very good situation : only one direction is really working.
The secondary test is simply a convection with an angle, exactly atan(1/10) / pi180. = 5,71059314 degree*. Therefore, after 10 revolution, the vortex should still be in the center. The only difference is a small velocity component to the Y direction (south to north).
|Convection speed x||Uc = 170m/s (Mach 0.5)|
|Convection speed y||Vc = 17m/s|
Turbulence modeling must be carefully assessed, starting with cases where the analytical theory allows to be quantitative. The first test case is a turbulent channel.
Streamwise velocity (sides) and wall-shear stress (top) of turbulent flow between two parallel plates SC13 Research Highlight: Petascale DNS of Turbulent Channel Flow
The first turbulent channel is defined in the POF article of Moser: Robert D. Moser, John Kim, and Nagi N. Mansour. “Direct numerical simulation of turbulent channel flow up to Reτ = 590”. In: Physics of Fluids 11.4 (1999), pp. 943–945. doi: 10.1063/1.869966. url: https://doi.org/10.1063/1.869966.
|Coarse mesh - regular|
|Shape LxHxW||πH/2 x H x 0.289πH/2|
|Dimensions LxHxW||0,314 x 0,2 x 0,09 m|
|Cells||5,652 Millions (1314x200x90)|
|Turbulent flow between two parallel plates|
|Bulk Reynolds||10 000|
|Bulk Velocity||1,61268091 m/s|
|Skin Friction coef.||5.908e-3|
|Forcing term||0,089179448 kg/m2/s2|
This second test comes from Large eddy simulation study of fully developed wind-turbine array boundary layers Physics of Fluids 22, 015110 (2010); https://doi.org/10.1063/1.3291077 Marc Calaf, Charles Meneveau, and Johan Meyers
|Coarse mesh - regular|
|Shape LxHxW||11H x H x 0.31H|
|Cells||34.1 Millions (1100 x 100 x 310)|
|Atmospheric boundary layer|
|Bulk Velocity||5,85 m/s|
|Skin Friction coef.||1,25E-02|
|Forcing term||0,000248284 kg/m2/s2|