Implementation of the SST - DDES model in Code_Saturne

This page contains the equations necessary for the implementation of the $k-\omega$ SST - DDES model into Code Saturne v2.0.1.

See Spalart, P.R. et al. A New Version of Detached-eddy Simulation, Resistant to Ambiguous Grid Densities. Theoretical and Computational Fluid Dynamics 20, 181-195(2006).

Source term for $k$ equation

Destruction term in the $k$ equation

  \begin{equation*} \beta k \omega F_{DDES} \end{equation*}(1)

Where the function $F_{DDES}$ is:

  \begin{equation*} F_{DDES} = \frac{L_{RANS}}{L_{RANS} - f_{d} \ max \left(0,L_{RANS} - L_{LES}\right)} \end{equation*}(2)

  \begin{align*} f_{d} \ &= 1 - tanh\left(\left[8r_{d}\right]^{3}\right) \\ r_{d}  \ & = \ \frac{\nu_{t} + \nu}{\sqrt{U_{i,j}U_{i,j}}\kappa^{2}d_{w}^{2}} \\ \end{align*}(3)

The length scales for the SST model are:

  \begin{align*} L_{RANS} \ &= \ \frac{\sqrt{k}}{\beta \omega} & L_{LES} \ & = \ C_{DDES}\Delta \\ \end{align*}(4)

Where, $\kappa = 0.41$, $C_{DDES} = 0.65$ and $d_{w}$ is the distance to the wall

Decaying Homogeneous Isotropic Turbulence (DHIT)


Modified Code_Saturne v2.0.1 subroutines


  • include and define the index, IDDES, which turns off the change in K transport equation if it is equals to zero and enables it when it is one.
  • include and define $C_{DDES}$.


  • Extra memory is required for the storage of the wall distance and $\sqrt{U_{i,j}U_{i,j}}$. The call headers need to be changed to include extra working arrays, W10 and W11. This is done for the SST-SAS model already.

  • W10 and W11 defined as double precision.

The DDES model will run using an index argument, where if IDDES.EQ.1 then the DDES modification will be used and if IDDES.EQ.0 then the standard SST will be run.

  • Working array W10 is $\sqrt{U_{i,j}U_{i,j}}$

  • Working array W11 is $d_{w}$

  • include IF statement for ISAS and IDDES as they both use W10 and W11

Source terms

  • Calculate $L_{RANS}$.

  • Calculate $r_{d}$

  • Calculate $f_{d}$

  • Calculate $F_{DDES}$

  • Add an if statement to the $k$ equation, where if IDDES.Eq.1 then the $k\beta\omega$ becomes $k\omega\beta F_{DDES}$

tridim.F (already done for SST-SAS model)

  • Change memkom call to include extra working arrays W10 and W11

  • Change call to turbkw, to include extra working arrays W10 and W11

memkom.F (already done for SST-SAS model)

  • Add extra working arrays, IW10, IW11

  • Change definitions, integers for IW10, IW11

  • Change memory pointers to include new working arrays


  • set default value, IDDES= 0

  • include incddes.h

  • include default values for $C_{DDES}$


  • IDDES = 0
  • $C_{DDES}$ = 0.65
  • include incddes.h


  • include incddes.h
  • Include printout for IDDES
  • include printout for $C_{DDES}$


  • include incddes.h
  • include an IF statement to check that SAS and DDES cannot run at the same time.

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Topic attachments
I Attachment Action Size Date Who Comment
jpgjpg cddes_sst_etc.jpg manage 133.4 K 2011-06-19 - 21:59 NeilAshton  
pdfpdf cddes_sst_etc.pdf manage 151.2 K 2011-06-19 - 21:58 NeilAshton cddes calibration - sst ddes
Topic revision: r12 - 2012-08-05 - 14:42:53 - AshrafHussein
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25 Mar 2019


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