Channel flow benchmarks

• DNS datasets to validate Code_Saturne

• Effect of complex grids

hexa, non-conform, tetra

• Low Reynolds number tests Ret = 100 no turbulence model

• Ret = 395 tests subgrid scale model tests

• Towards high Reynolds numbers subgrid scale models at high Reynolds

numbers

Channel flow benchmarks: « classic » DNS

• DNS Ret = 180

• Box 4 x 2 x 2, Grid 192 x 128 x 160 (4M cells) Same grid as Mansour, Kim & Moin

• Results include velocity, shear and normal stresses (<u>, <u’v’> etc… )

Triple correlations (<v’u’u’> etc…)

Terms in turbulent kinetic energy budget

Terms in the components of each budget

Channel flow benchmarks: DNS Ret =180

• Grid adapted for a

spectral code

• but applied to a non

spectral code

Channel flow benchmarks: DNS Ret =180

• Grid adapted for a spectral code

• but applied to a non spectral code

Channel flow benchmarks: DNS Ret =180

• Grid adapted for a spectral code

• but applied to a non spectral code

Channel flow benchmarks: DNS Ret =180

Channel flow benchmarks: DNS Ret =180

Channel flow benchmarks: DNS Ret =180

Channel flow benchmarks: Code_Saturne test grids

Hexahedral Non-conform (hexa)

Box 2 x 2 x

440,000 elements

Tetrahedral

Channel flow benchmarks: Ret = 100

• DNS 880k cells for same box size

• tests 440k cells

• Tetra poorly resolved difference in grid oneach wall

• Hexa too coarse at wall

Channel flow benchmarks: Ret = 100

• turbulence kinetic energy • weaknesses of each case become more clear

Channel flow benchmarks: Ret = 395

• velocity

Channel flow benchmarks: Ret = 395

• shear stress

Channel flow benchmarks: Ret = 395

• normal stresses

Channel flow benchmarks: Ret = 395

• tke

Channel flow benchmarks: high Reynolds numbers

• Box 6 x 2 x2, Grid 11 x 11 x 11 (1.3k cells)

        Ensure the tubes don’t touch, Ensure that sodium cannot get trapped (particularly important with respect to the neutronic reactions),        Reduce vibrations within the tube bundle,Improve the mixing near the heater and increase the rate of heat exchange.

Detail of the tubes that make up a bundle inside a SFR reactor

Thermal radiation

A z=100mm A z=140mm

First attempts to simulate the fluid