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- - **divU-terms in k-eps equations**
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divU-terms in k-eps equationsDear all!
Could somebody tell me please, where the terms >> fvm::SuSp(((2.0/3.0)*C1_ + C3_)*rho_*divU, epsilon_) and >> fvm::SuSp((2.0/3.0)*rho_*divU, k_) in the dissipation- and k-equation of the compressible RAS model come from (kEpsilon.C)? I searched the forum for further explanation but was not successful. Thanks in advance!! Aram |

They come from the double inner product of the velocity gradient with the Reynolds stress tensor in the production terms
i.e, for the epsilon equation, there should be a production term C1*R_{ij}&&grad(U) in the kEpsilon.C implemented in foam, R_{ij} = (2.0/3.0)*I)*k_ - (mut_/rho_)*dev(twoSymm(fvc::grad(U_)) is split into two parts for stability reasons the first term C1_*G*epsilon_/k_ contains the contribution from the second term in the R_{ij} equation the second term - fvm::SuSp(((2.0/3.0)*C1_ + C3_)*rho_*divU, epsilon_) contains the contribution from the (2/3)I*k term Best, Nat |

Nat,
thanks a lot for the clarification!! Best regards, Aram |

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